tag:blogger.com,1999:blog-84756093239868905022024-03-05T19:00:01.578+05:30TEKKNOMANIAVishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-8475609323986890502.post-37991676228567372542007-07-03T13:31:00.000+05:302007-07-03T13:37:24.393+05:30GREAT DATES IN RAILROAD HISTORY.<span style="font-weight: bold; color: rgb(51, 102, 255);font-family:trebuchet ms;font-size:180%;" >Railroads</span><br /><br /><ul><li><span style="color: rgb(255, 0, 0);">1630</span> - A man named Beaumont laid rails on a highway in England to transport coal from the Newcastle mines. This is the first railroad known in history.</li><li><span style="color: rgb(255, 0, 0);">1765</span> - James Watt constructed his first steam engine at the Corson Iron Works, Glasgow, Scotland.</li><li><span style="color: rgb(255, 0, 0);">1776</span> - The first iron rails, of which we have a complete account, were cast with a perpendicular ledge instead of the flange on modern wheels.</li><li><span style="color: rgb(255, 0, 0);">1801 </span>- A short line of track for a horse railroad was laid between Wandsworth and Croydon in the suburbs of London - the first chartered railroad on record.</li><li><span style="color: rgb(255, 0, 0);">1804</span> - The first attempt to utilize steam power on a railroad was made by a Cornishman named Trevithick, who ran a locomotive attached to several wagons in South Wales.</li><li><span style="color: rgb(255, 0, 0);">1827</span> - The first American railroad, from Quincy, Massachusetts, to the Neponset River, was completed.</li><li><span style="color: rgb(255, 0, 0);">1828</span> - Charles Carroll, the last surviving signer of the Declaration of Independence, laid, on July 4, the first rail of the Baltimore and Ohio Railroad.</li><li><span style="color: rgb(255, 0, 0);">1829 </span>- The Stourbridge Lion, the first steam locomotive ever seen in America, had its trial trip over the line of the Delaware and Hudson Canal and Railroad Company. In England, Stephenson's locomotive, The Rocket, won the prize of $2,500 offered by the directors of the Liverpool and Manchester Railway.</li><li><span style="color: rgb(255, 0, 0);">1830</span> - The first section of the Baltimore and Ohio Railroad, fifteen miles in length, was opened. Over it Peter Cooper ran his little locomotive, Tom Thumb, to prove that engines could be used on curves. The Best Friend, the first locomotive built in America for actual service, began regularly to haul freight on the South Carolina Railroad.</li><li><span style="color: rgb(255, 0, 0);">1842</span> - The whole of the Boston and Albany was completed, the first road to be operated as an important through route. The New York Central route to Buffalo was opened, though the various companies along the line were not consolidated until eleven years later.</li><li><span style="color: rgb(255, 0, 0);">1844</span> - With the aid of the government, Professor Morse built his pioneer telegraph line between Baltimore and Washington.</li><li><span style="color: rgb(255, 0, 0);">1846</span> - The Pennsylvania Railroad was chartered.</li><li><span style="color: rgb(255, 0, 0);">1853</span> - Eleven railroads were consolidated into the New York Central.</li><li><span style="color: rgb(255, 0, 0);">1854</span> - The Mississippi River was first reached by the Chicago and Rock Island Road.</li><li><span style="color: rgb(255, 0, 0);">1858</span> - Railroad building was pushed as far West as the Missouri River, the Hannibal and St. Joseph reaching that river.</li><li><span style="color: rgb(255, 0, 0);">1868</span> - George Westinghouse invented the air-brake.</li><li><span style="color: rgb(255, 0, 0);">1869</span> - The Union and Central Pacific lines were joined, making a through railroad route from the Atlantic to the Pacific.</li><li><span style="color: rgb(255, 0, 0);">1870</span> - The Chicago and Omaha pool was formed, the first pool on a large scale in the history of American railroading.</li><li><span style="color: rgb(255, 0, 0);">1887</span> - The Interstate Commerce Commission was established to have supervision over railroad rates.</li><li><span style="color: rgb(255, 0, 0);">1901</span> - The Northern Securities Company was organized to control the transcontinental railroads.</li><li><span style="color: rgb(255, 0, 0);">1904</span> - The United States Supreme Court, by a decision of five to four, held that the Northern Securities Company was in restraint of trade and was therefore illegal.</li><li><span style="color: rgb(255, 0, 0);">1906</span> - The Hepburn bill was passed by Congress, increasing the size and powers of the Interstate Commerce Commission.</li></ul>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-71113076817008537772007-06-28T13:47:00.000+05:302007-06-28T14:01:45.595+05:30EXODUS3000:A Game for Earning<span style="color:black;"><br /></span><span style="color:black;"><img src="http://www.exodus3000.com/welcome.jpg" /> </span><br /><br /><span style="color:black;"><span style="font-size:100%;">Upgrade, attack, defend, form alliances, and earn real cash and win prizes.<br /><br /> This is note on this gaming site. I think most of u have got it. For those who didn't I'll tell u in the simple words.<br /> This is an strategy game where you are supposed to be in Mars.When you sign up and enter the game you will see Homebase with the four directions N, E,S and W. When you click on these you'll enter another zone like Volcano,where it's written mine the volcano.When you click on mine this volcano you'll earn Mars dollars in short MDs. With these you can upgrade your defense,Weopons,scouts,security and even radar. Similarly,there are zones like Ruins,Craters,Plains,etc.Most important the payouts.You can sell your MDs for $ according to the payouts.That's secondary I suppose. Newly upgraded cards even add to the exitement. So what are you waiting for? Come join us<br />LINK: </span></span><span style="color:black;"><span style="color:black;"><b>http://www.exodus3000.com/?r=vishal_6885<br />Enjoy,Play and Earn.<br /></b></span></span>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-34527066648176331802007-06-27T21:54:00.000+05:302007-06-27T22:10:32.939+05:30AWAITING MOBILES<b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style=";font-family:lucida grande;color:black;" ><span style="text-decoration: none; color: rgb(0, 0, 0);">Nokia E90</span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><span style="font-family:lucida grande;"> </span><br /></span></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><span><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></span></a><span><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1025" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=2&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="150" width="200" /></span></span></a></span></b></span><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-style: italic;font-family:georgia;color:black;" ><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br />The world's largest mobile-phone maker launched the second generation of its successful E-series business phones at the 3GSM trade show in Barcelona . Leading the trio is the E90 Communicator, a mini computer with support for Wi-Fi and HSDPA-enhanced 3G with integrated GPS and route mapping.<br />A worthy successor to the previous Communicator 9500 which was launched over two years ago, E90 Communicator comes with a 4-inch wide screen that allows full-width Web browsing for the first time. It also features <span style="color: rgb(51, 102, 255);">integrated GPS</span> to allow turn-by-turn navigation.<br />The phone that could work as a phone, entertainment device and videoconferencing tool, will also offer an FM radio, a music player, a video player and two cameras -- a 3.2 megapixel one with flash and a second camera for video conferencing.<br />First deliveries of phone are expected during the second quarter of 2007, with global availability during the third quarter of this year.<br /></span></span><span style="font-style: italic;font-family:georgia;color:black;" ><span style="text-decoration: none; color: rgb(0, 0, 0);"><br />Nokia N77</span></span><span style="font-style: italic;font-family:georgia;color:black;" ><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal; font-style: italic;font-family:georgia;" ><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></a><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-weight: normal;"><br /></span><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1026" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=3&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="163" width="300" /></span></span></a></span></b><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >Another big launch from the company is N77 -- its first mid-priced mobile-TV phone (its second so far). The phone will be able to receive TV signals broadcast in DVB-H (Nokia?s own TV technology platform). While Nokia and other European phone makers favour the homegrown DVB-H technology for watching broadcasts on cellphones, rival formats such as MediaFlo from Qualcomm and DMB are getting there too. </span><br /><span style="font-style: italic;font-family:georgia;" >The N77 features a wide 2.4-inch screen, high-quality stereo sound and alerts when programmes are about to start. However, the Nokia N77 is much more than just live TV. Designed to work on 3G (WCDMA 2100 MHz), EDGE and GSM (900/1800/1900 MHz) networks, Nokia N77 is based on S60 3rd Edition software on Symbian OS. </span><br /><span style="font-style: italic;font-family:georgia;" >The N77, which will start shipping in the second quarter, will cost 370 Euros ($480), roughly half the price of the N92.</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">Mobile Ameo</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></a><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-weight: normal;"><br /></span><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1027" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=4&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="265" width="250" /></span></span></a></span></b><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >Here comes a phone with a hard drive. T-Mobile (a unit of Deutsche Telekom and one of the operators in Germany ) has unveiled a phone with a hard disk disk (HDD), saying the pocket-sized device with a 13-centimetre screen would go on sale in Germany just before Cebit show in March. </span><br /><span style="font-style: italic;font-family:georgia;" >Called Ameo, the phone contract manufactured by HTC uses Microsoft's operating system Windows Mobile 5.0. It would cost about 500 euros ($650) bundled with two years of phone service. </span><br /><span style="font-style: italic;font-family:georgia;" >It has a 8 GB HDDD and looks more like a mini laptop. Its best feature is its detachable 13-centimetre wide keyboard and upright display. However, T-Mobile has no immediate plans to sell it in the US or rest of Europe .</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">BlackBerry 8800</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></a><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1028" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=5&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="182" width="250" /><br /></span></span><span style="color:black;"><span style="font-weight: normal; color: windowtext; text-decoration: none;"><br /></span></span></a></span></b><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >Barely eight months after it introduced its first feature-rich multimedia device Pearl , Research In Motion has decided to give a Pearl-like finish to some other handsets. It has debuted another Pearl look-alike device 8800, a full-keyboard model that can play music and videos, besides handling e-mails as efficiently as ever. The company is billing the 8800 as the thinnest BlackBerry to date, measuring 0.55 inches from front to back. </span><br /><span style="font-style: italic;font-family:georgia;" >New features include an instant-messaging client that can chat to buddies on Yahoo IM and Google Talk, plus RIM's own browser. The 8800 also comes with a media player and an external storage slot for removable microSD memory cards. </span><br /><span style="font-style: italic;font-family:georgia;" >Above all, it uses a <span style="color: rgb(51, 102, 255);">GPS chipset</span> for mapping and navigation that finds its way in a BlackBerry device for the first time and will compete with Nokia's 6110 Navigator phone. RIM has partnered with California-based navigation solutions firm TeleNav, which also offers similar versions of the software for Windows Mobile, the Palm operating system, Symbian, Qualcomm's Brew, and the Java-based J2ME environment from Sun Microsystems. So the advantage to RIM could only be temporary. </span><br /><span style="font-style: italic;font-family:georgia;" >Besides, the 8800 is among the new crop of handsets that some feel could also bite into Apple iPhone's marketshare somewhat.</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">HP iPAQ 500</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></a><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1029" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=6&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="317" width="250" /></span></span><span style="color:black;"><span style="font-weight: normal; color: windowtext; text-decoration: none;"><br /></span></span></a></span></b><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >Another big launch at 3GSM World Congree 2007 was the Hewlett-Packard iPaq 500 smartphone. Hewlett Packard unveiled its first smart phone, a slimmed-down iPaq that will be among the first Windows Mobile 6 handsets when it launches by second quarter this year. </span><br /><span style="font-style: italic;font-family:georgia;" >The 500 series will be the first iPaqs that look like cellphones, with phone keypads instead of QWERTY keyboards or touch screens and styli. iPaq 500 comes with VOIP compatibility, push e-mail, Microsoft Internet Explorer and Outlook Mobile. The phone features 1.3-megapixel camera, Bluetooth, 64MB of memory and 128MB of storage with a micro SD card slot to expand memory. </span><br /><span style="font-style: italic;font-family:georgia;" >The iPaq 500 connects to the Internet via GSM/GPRS/Edge networks, as well as via Wi-Fi. The handset also allows users to play music and videos, store photos and play games on the device.</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">Samsung Ultra Smart F700</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><span><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></span></a><span><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1030" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=7&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="471" width="250" /></span></span></a></span></b></span><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >If Nokia has kicked so much dust in Barcelona , could Samsung be far behind? With its newest handset Ultra Smart F700, the </span><br /><span style="font-style: italic;font-family:georgia;" >Korean giant has joined Apple and its arch-rival LG into the club of touchscreen mobile phones manufacturers. </span><br /><span style="font-style: italic;font-family:georgia;" >The phone is Samsung's first that is compatible with 3G (third generation) WCDMA (Wideband Code Division Multiple Access) in addition to GSM (Global System for Mobile Communications) . It also works with HSDPA and EDGE data transmission systems on 3G networks and can receive data at up to 7.2Mbps (bits per second). </span><br /><span style="font-style: italic;font-family:georgia;" >The phone features a 2.8-inch 440x240 screen to control calling, Internet access, and music functions. Media playback support includes multiple AAC audio formats, Real, and variants of MPEG-4 including H.264. </span><br /><span style="font-style: italic;font-family:georgia;" >It also includes VibeTonz, a vibration system introduced in the recent W559 that simulates tactile feedback to touchscreen presses. And unlike Apple's iPhone, where typing on a small screen with your thumbs can leave you sore, F700 includes a slide-out keyboard to accommodate typing. </span><br /><span style="font-style: italic;font-family:georgia;" >And that is not all! The phone has a 5-megapixel camera with auto-focus that is far superior than iPhone's meager 2-megapixel offering. But of course, it has a microSD slot that will help expand the memory you would require for storing the humongous 5 MP photos, and music.</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">Apple iPhone</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></a><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-weight: normal;"><br /></span><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1031" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=8&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="297" width="250" /></span></span></a></span></b><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >The iPhone, which has no conventional buttons, instead uses a large touch-screen. The firm has patented keyboard technology on the 11.6 mm thick phone calling it "multi-touch" . The 3.5 inch touch-screen- controlled device plays music, surfs the Internet and delivers voice mail and email differently. </span><br /><span style="font-style: italic;font-family:georgia;" >The iPhone comes with a built-in, 2 MP digital camera as well as a slot for headphones and a SIM card. It runs Apple's OS X operating system, and has the Safari browser for Web access. The handset dispenses with buttons altogether, in favour of a powerful screen that responds to touch. It has a proximity sensor that automatically deactivates the screen and turns off the touch sensor when the device is raised to a user's face. </span><br /><span style="font-style: italic;font-family:georgia;" >Music is automatically muted when a phone call comes in. The phone will play videos in widescreen format and automatically senses whether the screen is being held vertically or horizontally. </span><br /><span style="font-style: italic;font-family:georgia;" >Has built-in Wi-Fi and Bluetooth and includes free BlackBerry-style 'push' email service from Yahoo. Apple is partnering with Yahoo Inc. on Web-based email and Google Inc on maps. To make a call, users can tap out the number on an on-screen keypad or scroll through their contacts and dial with a single touch. To zoom in on a photo or Web site, tap twice. To zoom out, tap once with two fingers.</span><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">LG Prada</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><span><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></span></a><span><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1032" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=9&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="433" width="250" /></span></span></a></span></b></span><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-style: italic;font-family:georgia;color:black;" ><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br />This is the phone for which the maker LG Electronics has officially accused Apple of copying the design for its newly launched iPhone last month.<br />LG Electronics and PRADA unveil the first completely touch screen mobile phone. The PRADA Phone by LG introduces the world?s first advanced touch interface which eliminates the conventional keypad. The phone comes with 3.0-inch display and Bluetooth 2.0 and a 2 megapixel camera featuring Schneider-Kreuznach lens and LED flash. It also features a player supporting MPEG4, H.264, a document viewer and an audio player with support for MP3/ACC/ACC+ /WMA/RA format.<br />The PRADA Phone by LG will be available with prices starting from 600 Euros at selected PRADA stores in the UK , France , Germany and Italy by the end of this month, followed by countries in Asia such as Hong Kong , Taiwan , and Singapore by late March.</span></span><span style="color:black;"><span style="text-decoration: none;color:black;" ><br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">Motorola Rizr Z8</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><span><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></span></a><span><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1033" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=10&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="612" width="283" /></span></span></a></span></b></span><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="font-style: italic;font-family:georgia;color:black;" ><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br />Motorola, the world's second-biggest mobile phone maker introduced a new phone design, which slides open and bends to bring the microphone closer to the user's mouth. The Rizr Z8, unveiled at the 3GSM wireless trade show in Barcelona, uses software from Symbian, which specializes in advanced cellphones and is more often found in phones from Nokia, Motorola's bigger rival.<br />The new high-speed wireless Rizr Z8 slides open to reveal a keyboard and, unlike traditional sliders, it has an automatic hinge that tilts the keyboard and locks the phone into a V-shape to make it easier to talk into.<br />The Rizr Z8 will also support television-quality video playback and has a slot for a memory card with up to 4 gigabytes of storage space. The product will be Motorola's fourth phone based on Symbian technology.<br /></span></span><span style="color:black;"><span style="text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-family:lucida grande;">Nokia N6110</span></span></span><span style="color:black;"><span style="font-weight: normal; text-decoration: none;color:black;" ><br /></span></span><span style="font-weight: normal;"><br /></span></a></span></b><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><b><span style="font-family:Times New Roman;font-size:100%;"><span style="font-weight: bold; font-size: 12pt;"></span></span></b><span><b><span style="font-family:Times New Roman;font-size:100%;"></span></b></span></a><span><b><span style="font-family:Times New Roman;font-size:100%;"><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; color: black; text-decoration: none;"><img id="_x0000_i1034" title="www.friendsmail.net.tc" alt="g u r l z g r o u p [www.friendmails.net.tc]" src="http://attach.in.mail.yahoo.com/in.f89.mail.yahoo.com/ym/in/ShowLetter?box=Inbox&MsgId=1903_75687641_1895601_3624_235112_0_18109_347235_2172773502&bodyPart=11&YY=78390&y5beta=yes&y5beta=yes&order=down&sort=date&pos=0&Idx=2" name="www.gurlzgroup.tk" border="0" height="444" width="200" /></span></span></a></span></b></span><br /><b><span style=";font-family:Times New Roman;font-size:100%;" ><a rel="nofollow" title="Join Gurlzgroup (www.friendmails.net.tc)" target="_blank" href="http://groups.yahoo.com/group/gurlzgroup"><span style="color:black;"><span style="font-weight: normal; text-decoration: none; color: rgb(0, 0, 0);"><br /><span style="font-style: italic;font-family:georgia;" >One of the hottest buzzwords in the mobile industry since sometime has been: Location-based services. The services primarily allow people to view where they are on a map, search for points-of-interests (POI) around them and create routes to get them there free of charge. However, navigation by mobile phone has been slow to catch on. Courtesy, small phone screens, short battery life and the directions and maps that often lacked accuracy. </span><br /><span style="font-style: italic;font-family:georgia;" >Taking a cue, the world?s biggest cellphone manufacturer Nokia unveiled its first mass market navigation-enabled phone, the N6110 Navigator. The launch unwraps company's plans to make a big push in location-based services. </span><br /><span style="font-style: italic;font-family:georgia;" >Nokia 6110 Navigator is a <span style="color: rgb(51, 51, 255);">GPS-enabled mobile phone</span> that features integrated maps and turn-by-turn directions with voice guidance and turn arrows pointing users in the appropriate direction. The Nokia 6110 Navigator can also provide users with traffic information, weather services and travel guides. According to a company spokesperson, Nokia would launch "a number" of navigation devices in 2007.</span> </span></span></a></span></b>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-1205592875643663652007-06-26T16:14:00.000+05:302007-06-26T16:30:45.422+05:30GPS ENABLED PHONES<span style="text-decoration: underline;"><span style="font-weight: bold;"><span style="font-family: georgia;">SE K530 with GPS</span><br /><br /><br /><br /><br /><br /></span></span> <span id="intelliTxt"> <div style="float: right;"><img title="K530 does GPS as well" alt="K530 does GPS as well" src="http://www.ubergizmo.com/photos/2007/6/se-k530.jpg" border="0" /></div>Looks like Sony Ericsson will be jumping aboard the GPS bandwagon with its K530 handset. This GPS navigation capable cellphone is the first from Sony Ericsson's stable to do so, boasting full point-to-point navigation. Not only do you get help in knowing where to go, the K530 also delivers weather forecasts for your current location if the need arises. The K530 is also supports 3G connectivity, letting your surf the Internet and catch up on the latest news via a RSS reader. Other features include a 2 megapixel camera, 16MB of internal memory, and a Memory Stick Micro memory card slot. There is no word on pricing details, but the K530 will hit the streets when Q3 2007 rolls around.<br /><br /><br /><br /><br /><br /><br /><br /><br /></span><br /> <h3 class="post-title"><span style="font-size:100%;"><a href="http://gps.ubergizmo.com/15/archives/2007/04/symbol_technologies_announce_mc35.html">Symbol Technologies announce MC35</a></span></h3> <p style="color: rgb(204, 204, 204); font-size: 70%;"><br /></p><br /> <span id="intelliTxt"> <div align="center"><img title="Symbol Technologies announce MC35" style="margin: 0px;" alt="Symbol Technologies announce MC35" src="http://www.ubergizmo.com/photos/2007/4/symbol-mc35.jpg" border="0" /><br /></div><br /><p>Symbol Technologies has recently announced the MC35 Pocket PC phone that comes in a form factor which is similar to that of a PDA, featuring a whole host of connectivity options to keep you abreast with the latest happenings within the company. Each MC35 comes with built-in WiFi and Bluetooth connectivity, and integrated GPS navigation system, push email support, and the ability to access AT&T's high-speed wireless data network. The inclusion of Push-To-Talk functionality also helps you save money in the long run, especially when you need to communicate with colleagues and underlings who are on-site.</p> </span><br /><br /><br /><span style="font-weight: bold;font-size:100%;" >NOKIA N95 with GPS</span><br /><div align="center"><img title="Nokia N95 on sale in US " style="margin: 0px;" alt="Nokia N95 on sale in US " src="http://www.ubergizmo.com/photos/2007/4/nokia-n95.jpg" border="0" /><br /></div><br /><p>Those hankering after the Nokia N95 will be pleased to know that this "portable computer" is now up for sale in the U.S. across various Nokia Flagship stores, online, and selected wireless retailers. To give you an idea of what $749 can give you, the N95 boasts a 2-way slide design for different modes, WiFi, GPS, and Bluetooth connectivity, a 5 megapixel camera featuring Carl Zeiss optics, video recording, a TV-out port, a microSD memory card slot, integrated stereo speakers, and a 3.5mm stereo headset port among others.</p><br /><span id="intelliTxt"><br /><br /><br /><br /><br /><br /><br /></span><br /><p style="color: rgb(204, 204, 204); font-size: 70%;"><br /></p><span id="intelliTxt"><br /></span>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-12568980321362936172007-06-26T16:03:00.000+05:302007-06-26T16:14:34.634+05:30GPS RECEIVER<span id="intelliTxt"> <div align="center"><img title="PalmNavi F3501 GPS navigation system" style="margin: 0px;" alt="PalmNavi F3501 GPS navigation system" src="http://www.ubergizmo.com/photos/2007/6/palmnavi-f3501.jpg" border="0" /><br /></div><br /><p>The PalmNavi F3501 GPS navigation system was recently paraded at Computex 2007, and what you get is a fairly normal GPS navigation system. Features include a 3.5" touchscreen display, 3D graphics that make it easier to determine where your exact location is, and a 1800mAh li-ion battery that provides up to 8 hours of juice. A flip up GPS antenna produces superior reception, while MP3 and MPEG 4 support ensures you won't run out of entertainment options when going through the motions of a long road trip.</p> </span>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-37970851741870185932007-06-26T13:54:00.000+05:302007-06-26T14:37:57.306+05:30New 5 MP CAMERA PHONE FROM SE<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8eEOEjtBoYWYzD1aIr6b6dMxn9X5YOve67hx6j5B7GwyfLAYdXAJPuDKyW8Xz8OzyqbEHn2VF3fV5P2-zJ5hqs6A9w7-6EZPwTFCK_RGPAkwPEpk0sp-fkdJyad0I7bNh490SkiB01Bm6/s1600-h/1.jpg"><img style="cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8eEOEjtBoYWYzD1aIr6b6dMxn9X5YOve67hx6j5B7GwyfLAYdXAJPuDKyW8Xz8OzyqbEHn2VF3fV5P2-zJ5hqs6A9w7-6EZPwTFCK_RGPAkwPEpk0sp-fkdJyad0I7bNh490SkiB01Bm6/s320/1.jpg" alt="" id="BLOGGER_PHOTO_ID_5080296390316791506" border="0" /></a><br /><span style="font-size:130%;"><span style="font-family:georgia;">SONY ERICSSON K850 with 5MP Camera</span></span><br /><br /><br /><br /> SONY ERICSSON has announced the Cybershot K850 camera phone that <span id="intelliTxt">comes with a mind-blowing </span> 5MP camera with autofocus that includes a <span id="intelliTxt"> real xenon flash</span>, <span id="intelliTxt">a dedicated </span>shutter button, and the ability to record QVGA video at 30fps. <span id="intelliTxt">This photo-centric handset also boasts Sony Ericsson's BestPic multi-shot capability in addition to the Photo Fix system that adjusts photo brightness levels with a single click. </span>In addition, the K850 also supports quad-band GSM/EDGE/HSDPA, and offers MP3 playback, 40MB of memory, and the option to upgrade the memory through the help of M2 or microSD cards.<span id="intelliTxt">Sounds like a pretty solid handset on all accounts.<br /><br /><br /><br /><br />MORE IMAGES:<br /><br /></span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTeM1dwT6XdRKRLrK1WznyoiFPAdvnrrbtFppm1oQwVv86taaRcUiE-G-xTtrkwn_kqgpU0fNnL0yp5JC69H2MFI3D2lfVUAFUrlEscvKfmYGaq0ht1feapylBs71q4pxuaJQwSK57m_xm/s1600-h/showimage.php.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTeM1dwT6XdRKRLrK1WznyoiFPAdvnrrbtFppm1oQwVv86taaRcUiE-G-xTtrkwn_kqgpU0fNnL0yp5JC69H2MFI3D2lfVUAFUrlEscvKfmYGaq0ht1feapylBs71q4pxuaJQwSK57m_xm/s320/showimage.php.jpg" alt="" id="BLOGGER_PHOTO_ID_5080289651513104018" border="0" /></a><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1MMwEYKzWtVjJQiWTH1JXjUjuGAWjfF0y7czgUlQvyj2n_qr-ACahqVm7Y6Rpdp7_AiKPgfDYNokELKJl3mOSVyrHlKtJ4aVJZg_LrCybx9pNKXtauGzWHCJ2acvst7_XbbcwgU_CT75J/s1600-h/showimage.php2.jpg"><img style="cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1MMwEYKzWtVjJQiWTH1JXjUjuGAWjfF0y7czgUlQvyj2n_qr-ACahqVm7Y6Rpdp7_AiKPgfDYNokELKJl3mOSVyrHlKtJ4aVJZg_LrCybx9pNKXtauGzWHCJ2acvst7_XbbcwgU_CT75J/s320/showimage.php2.jpg" alt="" id="BLOGGER_PHOTO_ID_5080290132549441202" border="0" /></a><br /><br /> <br /> <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjN1bfrRulmcRJh8I9FFQNLeYBsLJIBgZZrYesRGIpkzc7QGejktfbjwFRHEfD6OKO8tS6Pe7Lp8M34qFmc78cvWaEH-LatbIcaVnKZYlGVkTySuUOzI7Pbefp83VwZ-4_7OjBoJrDXRTxA/s1600-h/sony_ericsson_cybershot_k850_cybershot.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjN1bfrRulmcRJh8I9FFQNLeYBsLJIBgZZrYesRGIpkzc7QGejktfbjwFRHEfD6OKO8tS6Pe7Lp8M34qFmc78cvWaEH-LatbIcaVnKZYlGVkTySuUOzI7Pbefp83VwZ-4_7OjBoJrDXRTxA/s320/sony_ericsson_cybershot_k850_cybershot.jpg" alt="" id="BLOGGER_PHOTO_ID_5080286361568155266" border="0" /></a><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOI-pSTfI9rLQvtZTZXQLGP4gsDB0DHQOTvDIXANtZPKBx007lzMQIa2m1zmG2ANTJWVK3CnhH5dwbVrA1nQ-ldZTM27vGtD9e3YXCCdemMLkrmfsZPp_LlwpCmC22BgP70CPPGVJAPuPE/s1600-h/showimage.php4.jpg"><img style="cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOI-pSTfI9rLQvtZTZXQLGP4gsDB0DHQOTvDIXANtZPKBx007lzMQIa2m1zmG2ANTJWVK3CnhH5dwbVrA1nQ-ldZTM27vGtD9e3YXCCdemMLkrmfsZPp_LlwpCmC22BgP70CPPGVJAPuPE/s320/showimage.php4.jpg" alt="" id="BLOGGER_PHOTO_ID_5080290403132380866" border="0" /></a><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><span id="intelliTxt"><br /><br /><br /><br /></span><span id="intelliTxt"> </span>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-70090949256125345582007-06-22T12:52:00.000+05:302007-06-22T12:56:52.158+05:30Applications of GIS<p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure1.jpg" alt="A color photograph of cave drawing." border="1" height="244" width="300" /></p> <p class="caption">Figure 1. Group of stags (cave painting), Lascaux Caves, France (Art Resources, N.Y.).</p><span style="font-weight: bold;"> GIS through history</span> <p>Some 35,000 years ago, Cro-Magnon hunters drew pictures of the animals they hunted on the walls of caves near Lascaux, France, (fig. 1). Associated with the animal drawings are track lines and tallies thought to depict migration routes. These early records followed the two-element structure of modern geographic information systems (GIS): a graphic file linked to an attribute database.</p> <br /> <table align="left" border="0" width="400"> <tbody><tr> <td valign="top" width="383"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure2.jpg" alt="An outline map with lines indicating pathways." border="1" height="328" width="383" /></p> <p class="caption">Figure 2. Tracks of caribou routes in Alaska from April 1985 to December 1986 (U.S. Fish and Wildlife Service).</p> </td> </tr> <tr><td> </td></tr> </tbody></table> <p>Today, biologists use collar transmitters and satellite receivers to track the migration routes of caribou and polar bears to help design programs to protect the animals. In a GIS, the migration routes were indicated by different colors for each month for 21 months (fig. 2). Researchers then used the GIS to superimpose the migration routes on maps of oil development plans to determine the potential for interference with the animals.</p><br /><br /><br /><br /><br /><br /><br /> <h4>Mapmaking</h4> <p>Researchers are working to incorporate the mapmaking processes of traditional cartographers into GIS technology for the automated production of maps.</p> <p>One of the most common products of a GIS is a map. Maps are generally easy to make using a GIS and they are often the most effective means of communicating the results of the GIS process. Therefore, the GIS is usually a prolific producer of maps. The users of a GIS must be concerned with the quality of the maps produced because the GIS normally does not regulate common cartographic principles. One of these principles is the concept of generalization, which deals with the content and detail of information at various scales. The GIS user can change scale at the push of a button, but controlling content and detail is often not so easy. Mapmakers have long recognized that content and detail need to change as the scale of the map changes. For example, the State of New Jersey can be mapped at various scales, from the small scale of 1:500,000 to the larger scale of 1:250,000 and the yet larger scale of 1:100,000 (fig.3a), but each scale requires an appropriate level of generalization (figs. 3b, c, and d).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure3a.jpg" alt="Sections of different scale maps in black and white." border="1" height="212" width="600" /></p> <p class="caption">Figure 3a. Digital revision of 1:100,000-scale digital line graph data to produce a 1:500,000-scale New Jersey State base map. Paneling and generalization are shown in three stages from 1:100,000 scale to 1:250,000 scale to 1:500,000 scale.</p> </td> </tr> <tr> <td valign="top" width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure3bcd.jpg" alt="Color line maps showing different scale maps." border="1" height="212" width="600" /></p> <p class="caption">Figure 3b, c, d. These digital maps of Bergen County, N.J. are all at the scale of 1:500,00. The information content of the maps has been reduced through the process of generalization in two stages, from 1:100,000 scale on the left to 1:250,000 in the center, then from 1:250,000 to 1:500,00 scale on the right.</p> </td> </tr> </tbody></table> <h4>Site selection</h4> <p>The U.S. Geological Survey (USGS), in a cooperative project with the Connecticut Department of Natural Resources, digitized more than 40 map layers for the areas covered by the USGS Broad Brook and Ellington 7.5-minute topographic quadrangle maps (fig. 4). This information can be combined and manipulated in a GIS to address planning and natural resource issues. GIS information was used to locate a potential site for a new water well within half a mile of the Somers Water Company service area (fig. 5).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure4.jpg" alt="A color map of Connecticut." border="1" height="242" width="300" /></p> <p class="caption">Figure 4. USGS digital line graph map of the State of Connecticut from 1:2,000,000-scale data. The Broad Brook and Ellington 7.5-minute quadrangle areas are outlined in black in the upper middle.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure5.jpg" alt="A color outline and shape map of the water service area." border="1" height="242" width="300" /></p> <p class="caption">Figure 5. Map of the areas covered by the Broad Brook and Ellington 7.5-minute quadrangle showing the Somers Water Company service area at the scale of 1:24:000.</p> </td> </tr> </tbody></table> <p>To prepare the analysis, cartographers stored digital maps of the water service areas in the GIS. They used the proximity function in the GIS to draw a half-mile buffer zone around the water company service area (fig. 6). This buffer zone was the "window" used to view and combine the various map coverages relevant to the well site selection.</p> <table border="0" width="220"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure6.jpg" alt="A colored line map of water service buffer zone." border="1" height="180" width="200" /></p> <p class="caption">Figure 6. Enlarged view of figure 5 showing a half-mile buffer zone drawn around the service area of the Somers Water Company</p> </td> </tr> </tbody></table> <p>The land use and land cover map for the two areas shows that the area is partly developed (fig. 7). A GIS was used to select undeveloped areas from the land use and land cover map as the first step in finding well sites. The developed areas were eliminated from further consideration (fig. 8).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure7.jpg" alt="An outline map showing with colored areas showing land use." border="1" height="180" width="200" /></p> <p class="caption">Figure 7. Land use and land cover data for the area bounded by a half-mile buffer zone around the water company service area.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure8.jpg" alt="An outline map showing selected areas of land use." border="1" height="180" width="200" /></p> <p class="caption">Figure 8. Land use and land cover data shown in figure 7 have been reselected to eliminate developed areas.</p> </td> </tr></tbody></table> <p>The quality of water in Connecticut streams is closely monitored. Some of the streams in the study area were known to be unusable as drinking water sources. To avoid pulling water from these streams into the wells, 100-meter buffer zones were created around the unsuitable streams using the GIS, and the zones were plotted on the map (fig. 9). The map showing the buffered zones was combined with the land use and land cover map to eliminate areas around unsuitable streams from the analysis (fig. 10). The areas in blue have the characteristics desired for a water well site.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure9.jpg" alt="Map lines showing buffer zones." border="1" height="180" width="200" /></p> <p class="caption">Figure 9. Buffer zones of 100 meters are drawn around polluted stream in the water service area.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure10.jpg" alt="Map shapes showing buffer zones." border="1" height="180" width="200" /></p> <p class="caption">Figure 10. Buffered streams shown in figure 9 area subtracted from areas previously selected with the land use and land cover data.</p> </td> </tr> </tbody></table> <p>Point sources of pollution are recorded by the Connecticut Department of Natural Resources. These records consist of a location and a text description of the pollutant (fig. 11). To avoid these toxic areas, a buffer zone of 500 meters was established around each point (fig. 12). This information was combined with the previous two map layers to produce a new map of areas suitable for well sites (fig. 13).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure11.gif" alt="Map points with numbers 1 through 6." border="1" height="180" width="200" /></p> <p class="caption">Figure 11. Points sources of pollution in the water service area are identified and entered into a GIS.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure12.jpg" alt="Mapped circles." border="1" height="180" width="200" /></p> <p class="caption">Figure 12. Buffer zones of 500 meters are drawn around the point sources of pollution.</p> </td> </tr> <tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure13.jpg" alt="Mapped shapes showing buffer zones." border="1" height="180" width="200" /></p> <p class="caption">Figure 13. A new map is created in a GIS by eliminating the buffered sources of pollution from the previously selected areas shown in figure 10.</p> </td> </tr> </tbody></table> <p>The map of surficial geology shows the earth materials that lie above bedrock (fig. 14). Since the area under consideration in Connecticut is covered by glacial deposits, the surface consists largely of sand and gravel, with some glacial till and fine-grained sediments. Of these materials, sand and gravel are the most likely to store water that could be tapped with wells. Areas underlain by sand and gravel were selected from the surficial geology map (fig. 15). They were combined with the results of the previous selections to produce a map consisting of: (1) sites in underdeveloped areas underlain by sand and gravel, (2) more than 500 meters from point sources of pollution, and (3) more than 100 meters from unsuitable streams (fig. 16).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure14.jpg" alt="A map with color areas denoting geology." border="1" height="180" width="200" /></p> <p class="caption">Figure 14. Map of surficial geology of the water service area.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure15.jpg" alt="A map with color overlay." border="1" height="180" width="200" /></p> <p class="caption">Figure 15. Selection areas of sand and gravel from the map of surficial geology.</p> </td> </tr> <tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure16.jpg" alt="Mapped shapes showing sand and gravel areas." border="1" height="180" width="200" /></p> <p class="caption">Figure 16. Map produced by combining the areas composed of sand and gravel with previous selection from figure 13.</p> </td> </tr> </tbody></table> <p>A map that shows the thickness of saturated sediments was created by using the GIS to subtract the bedrock elevation from the surface elevation (fig. 17). For this analysis, areas having more than 40 feet of saturated sediments were selected and combined with the previous overlays.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure17.jpg" alt="A map with color overlays showing differences in surface." border="1" height="180" width="200" /></p> <p class="caption">Figure 17. A bedrock elevation subtracted from surface elevation by a GIS to show the thickness of water-saturated sediment.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure18.jpg" alt="A color area map with shapes representing the thicker areas." border="1" height="180" width="200" /></p> <p class="caption">Figure 18. Potential sites with saturated thickness of sediments greater than 40 feet.</p> </td> </tr> </tbody></table> <p>The resulting site selection map shows areas that are undeveloped, are situated outside the buffered pollution areas, and are underlain by 40 feet or more of water-saturated sand and gravel (fig. 18). Because of map resolution and the limits of precision in digitizing, the very small polygons (areas) may not have all of the characteristics analyzed, so another GIS function was used to screen out areas smaller than 10 acres. The final six sites are displayed with the road and stream network and selected place names for use in the field (fig. 19).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="500"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure19.jpg" alt="A color line and shape map showing named features." border="1" height="441" width="500" /></p> <p class="caption">Figure 19. Potential water well sites, roads, streams and place names.</p> </td> </tr> </tbody></table> <p>The process illustrated by this site selection analysis has been used for many common applications, including transportation planning and waste disposal site location. The technique is particularly useful when several physical factors must be considered and integrated over a large area.</p> <h4>Emergency response planning</h4> <p>The Wasatch Fault zone runs through Salt Lake City along the foot of the Wasatch Mountains in north-central Utah (fig. 20).</p> <table border="0" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure20.jpg" alt="A color shaded relief map." border="1" height="332" width="300" /></p> <p class="caption">Figure 20. Map of the area surrounding the USGS Sugar House 7.5-minute quadrangle, Salt lake City, Utah, showing the location of the Wasatch Fault zone.</p> </td> </tr> </tbody></table> <p>A GIS was used to combine road network and earth science information to analyze the effect of an earthquake on the response time of fire and rescue squads. The area covered by the USGS Sugar House 7.5-minute topographic quadrangle map was selected for the study because it includes both undeveloped areas in the mountains and a part of Salt Lake City. Detailed earth science information was available for the entire region.</p> <p>The road network from a USGS digital line graph includes information on the types of roads, which range from rough trails to divided highways (fig. 21). The locations of fire stations were plotted on the road network. A GIS function called network analysis was used to calculate the time necessary for emergency vehicles to travel from the fire stations to different areas of the city. The network analysis function considers two elements: (1) distance from the fire station, and (2) speed of travel based on the type of road. The analysis shows that under normal conditions, most of the area within the city will be served in less than 7 minutes and 30 seconds because of the distribution and density of fire stations and the continuous network of roads.</p> <p>The accompanying illustration (fig. 22) depicts the blockage of the road network that would result from an earthquake, assuming that any road crossing the fault trace would become impassable. The primary effect on emergency response time would occur in neighborhoods west of the fault trace, where travel times from the fire stations would be noticeably lengthened.</p> <br /> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure21.jpg" alt="A color line map showing access times prior to faulting." border="1" height="420" width="300" /></p> <p class="caption">Figure 21. Before faulting. Road network of area covered by the Sugar House quadrangle plotted from USGS digital line graph data, indicating the locations of fire stations and travel times of emergency vehicles. Areas in blue can receive service within 2½minutes, area in green within 5 minutes, areas in yellow within 7½ minutes, and areas in magenta within 10 minutes. Areas in white cannot receive service within 10 minutes. </p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure22.jpg" alt="A color line map showing access times after faulting." border="1" height="420" width="300" /></p> <p class="caption">Figure 22. After faulting, initial model. Network analysis in a GIS produces a map of travel times from the stations after faulting. The fault is in red. Emergency response times have increased for areas west of the fault.</p> </td> </tr> </tbody></table> <p>The Salt Lake City area lies on lake sediments of varying thicknesses. These sediments range from clay to sand and gravel, and most are water-saturated. In an earthquake, these materials may momentarily lose their ability to support surface structures, including roads. The potential for this phenomenon, known as liquefaction, is shown in a composite map portraying the inferred relative stability of the land surface during an earthquake. Areas near the fault and underlain by thick, loosely consolidated, water-saturated sediments will suffer the most intense surface motion during an earthquake (fig. 23). Areas on the mountain front with thin surface sediments will experience less additional ground acceleration. The map of liquefaction potential was combined with the road network analysis to show the additional effect of liquefaction on response times.</p> <p>The final map shows that areas near the fault, as well as those underlain by thick, water-saturated sediments, are subject to more road disruptions and slower emergency response than are other areas of the city (fig. 24).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure23.jpg" alt="A color shape and line map showing liquefaction regions." border="1" height="420" width="300" /></p> <p class="caption">Figure 23. Map of potential ground l liquefaction during an earthquake. The least stable areas are shown by yellows and oranges, the most stable by grays and browns.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure24.jpg" alt="A color line map showing final travel time after faulting." border="1" height="420" width="300" /></p> <p class="caption">Figure 24. After faulting, final model. A map showing the effect of an earthquake on emergency travel times is reduced by combining the liquefaction potential information from figure 23 with the network analysis from figure 22.</p> </td> </tr> </tbody></table> <h4>Three-dimensional GIS</h4> <p>To more realistically analyze the effect of the Earth's terrain, we use three-dimensional models within a GIS. A GIS can display the Earth in realistic, three-dimensional perspective views and animations that convey information more effectively and to wider audiences than traditional, two-dimensional, static maps. The U.S. Forest Service was offered a land swap by a mining company seeking development rights to a mineral deposit in Arizona's Prescott National Forest. Using a GIS, the USGS and the U.S. Forest Service created perspective views of the area to depict the terrain as it would appear after mining (fig. 25).</p> <table border="0"> <tbody><tr> <td valign="top" width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure25.jpg" alt=" A line map of surface elevations." border="1" height="229" width="600" /></p> <p class="caption">Figure 25. Prescott National Forest, showing altered topography due to mine development.</p> </td> </tr> </tbody></table> <p>To assess the potential hazard of landslides both on land and underwater, the USGS generated a three-dimensional image of the San Francisco Bay area (fig. 26). It created the image by mosaicking eight scenes of natural color composite Landsat 7 enhanced thematic mapper imagery on California fault data using approximately 700 digital elevation models at 1:24,000 scale.</p> <table border="0"> <tbody><tr> <td valign="top" width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure26.jpg" alt="A color photo map with lines showing avalanche areas." border="1" height="229" width="600" /></p> <p class="caption">Figure 26. Three-dimensional image of the San Francisco Bay created to assess the potential of land and underwater avalanches.</p> </td> </tr> </tbody></table> <a name="display"></a> <h3>Graphic display techniques</h3> <p>Traditional maps are abstractions of the real world; each map is a sampling of important elements portrayed on a sheet of paper with symbols to represent physical objects. People who use maps must interpret these symbols. Topographic maps show the shape of the land surface with contour lines. Graphic display techniques in GISs make relationships among map elements more visible, heightening one's ability to extract and analyze information.</p> <p>Two types of data were combined in a GIS to produce a perspective view of a part of San Mateo County, Calif. The digital elevation model, consisting of surface elevations recorded on a 30-meter horizontal grid, shows high elevations as white and low elevations as black (fig. 27). The accompanying Landsat thematic mapper image shows a false-color infrared image of the same area in 30-meter pixels, or picture elements (fig. d). A GIS was used to register and combine the two images to produce the three-dimensional perspective view looking down the San Andreas Fault (fig. 29).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="400"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure27.jpg" alt="A color picture showing DEM." border="1" height="313" width="400" /></p> <p class="caption">Figure 27. Digital elevation model of San Mateo County, Calif.</p> </td> </tr> <tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure28.jpg" alt="A color Landsat photograph." border="1" height="313" width="400" /></p> <p class="caption">Figure 28. Landsat Thematic Mapper image of San Mateo County, Calif.</p> </td> </tr> <tr> <td valign="top" width="400"><p> <img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure29.jpg" alt="A color perspective view." border="1" height="313" width="400" /></p> <p class="caption">Figure 29. Perspective view of San Mateo County, Calif.</p> </td> </tr> </tbody></table> <h4>Visualization</h4> <p>Maps have traditionally been used to explore the Earth. GIS technology has enhanced the efficiency and analytical power of traditional cartography. As the scientific community recognizes the environmental consequences of human activity, GIS technology is becoming an essential tool in the effort to understand the process of global change. Map and satellite information sources can be combined in models that simulate the interactions of complex natural systems.</p> <p>Through a process known as visualization, a GIS can be used to produce images— not just maps, but drawings, animations, and other cartographic products. These images allow researchers to view their subjects in ways that they never could before. The images often are helpful in conveying the technical concepts of a GIS to nonscientists.</p> <h4>Adding the element of time</h4> <p>The condition of the Earth's surface, atmosphere, and subsurface can be examined by feeding satellite data into a GIS. GIS technology gives researchers the ability to examine the variations in Earth processes over days, months, and years. As an example, the changes in vegetation vigor through a growing season can be animated to determine when drought was most extensive in a particular region. The resulting normalized vegetation index represents a rough measure of plant health (fig. 30). Working with two variables over time will allow researchers to detect regional differences in the lag between a decline in rainfall and its effect on vegetation. The satellite sensor used in this analysis is the advanced very high resolution radiometer (AVHRR), which detects the amounts of energy reflected from the Earth's surface at a 1-kilometer resolution twice a day. Other sensors provide spatial resolutions of less than 1 meter.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure30a.jpg" alt="A color globe showing European area." border="1" height="226" width="300" /></p> </td> <td valign="top" width="300"> <p> <img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure30b.jpg" alt="A color globe showing South America area." border="1" height="226" width="300" /></p> </td> </tr> <tr> <td colspan="2" valign="top" width="600"> <p class="caption">Figure 30. One time slice of the vegetation index for part of the globe from AVHRR data.</p> </td> </tr> </tbody></table> <h4>Serving GIS over the Internet</h4> <p>Through Internet map server technology, spatial data can be accessed and analyzed over the Internet. For example, current wildfire perimeters are displayed with a standard web browser, allowing fire managers to better respond to fires while in the field and helping homeowners to take precautionary measures (fig. 31).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/2figure31.jpg" alt="A color photo showing a pair of computer screen snapshots." border="1" height="379" width="600" /></p> <p class="caption">Figure 31. Wildfires burning for the past 24 hours accessible by means of a web browser and Internet map server GIS technology.</p> </td> </tr> </tbody></table> <h4>The future of GIS</h4> <p>Environmental studies, geography, geology, planning, business marketing, and other disciplines have benefitted from GIS tools and methods. Together with cartography, remote sensing, global positioning systems, photogrammetry, and geography, the GIS has evolved into a discipline with its own research base known as geographic information sciences. An active GIS market has resulted in lower costs and continual improvements in GIS hardware, software, and data. These developments will lead to a much wider application of the technology throughout government, business, and industry.</p> <p>GIS and related technology will help analyze large datasets, allowing a better understanding of terrestrial processes and human activities to improve economic vitality and environmental quality.</p><a name="applications"></a>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-55970372938678413062007-06-22T12:13:00.000+05:302007-06-22T12:51:21.637+05:30GIS:Through Pictures<p> Geographic information system (GIS) technology can be used for scientific investigations, resource management, and development planning. For example, a GIS might allow emergency planners to easily calculate emergency response times in the event of a natural disaster, or a GIS might be used to find wetlands that need protection from pollution.<br /> A GIS is a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information; that is, data identified according to location. Practitioners also define a GIS as including the procedures, operating personnel, and spatial data that go into the system.</p> <a name="how"></a> <h3>How does a GIS work?</h3> <p> The power of a GIS comes from the ability to relate different information in a spatial context and to reach a conclusion about this relationship. Most of the information we have about our world contains a location reference, placing that information at some point on the globe. When rainfall information is collected, it is important to know where the rainfall is located. This is done by using a location reference system, such as longitude and latitude, and perhaps elevation. Comparing the rainfall information with other information, such as the location of marshes across the landscape, may show that certain marshes receive little rainfall. This fact may indicate that these marshes are likely to dry up, and this inference can help us make the most appropriate decisions about how humans should interact with the marsh. A GIS, therefore, can reveal important new information that leads to better decisionmaking.</p> <p> Many computer databases that can be directly entered into a GIS are being produced by Federal, State, tribal, and local governments, private companies, academia, and nonprofit organizations. Different kinds of data in map form can be entered into a GIS (<span style="color: rgb(0, 0, 102);">figs. 1a, 1b, 1c, 1d, 1e, 1f, and 2</span>)<br /> A GIS can also convert existing digital information, which may not yet be in map form, into forms it can recognize and use. For example, digital satellite images can be analyzed to produce a map of digital information about land use and land cover (<span style="color: rgb(0, 0, 102);">figs. 3 and 4</span>). Likewise, census or hydrologic tabular data can be converted to a maplike form and serve as layers of thematic information in a GIS (<span style="color: rgb(0, 0, 102);">figs. 5 and 6</span>).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1a.jpg" alt="A line map showing roads with different colored lines representing types of roads." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1a</span>. U.S. Geological Survey (USGS) digital line graph (DLG) data of roads.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1b.jpg" alt="A line map with various colors representing bodies of water and streams/rivers." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1b</span>. USGS DLG of rivers.</p> </td> </tr> <tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1c.jpg" alt="A map showing contour lines." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1c</span>. USGS DLG of contour lines (hypsography).</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1d.jpg" alt="A black and white picture showing DEM shadings representing contours." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1d</span>. USGS digital elevation (DEM).</p> </td> </tr> <tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1e.jpg" alt="A section of a color topographic map." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1e</span>. USGS scanned, rectified topographic map called a digital raster graphic (DRG).</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure1f.jpg" alt="A black and white picture of map overlaying an aerial photograph." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 1f</span>. USGS digital orthophoto quadrangle (DOQ).</p> </td> </tr> <tr> <td valign="top" width="400"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure2.jpg" alt="A section of a color geologic map." border="1" height="449" width="400" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 2</span>. USGS geologic map.</p> </td> </tr> <tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure3.jpg" alt="A colored modified satellite image." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 3</span>. Landsat 7 satellite image from which land cover information can be derived.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure4.jpg" alt="A color picture showing an analysis graphic." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 4</span>. Satellite image data in figure 3 have been analyzed to indicate classes of land uses and cover.</p> </td> </tr> <tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure5.jpg" alt="A color picture showing part of a computer screen display." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 5</span>. Part of a census data file containing address information.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure6.jpg" alt="A black and white picture of computer screen display of a graph." border="1" height="232" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 6</span>. Part of a hydrologic data report indicating the discharge and amount of river flow recorded by a particular streamgage that has a known location</p> </td> </tr> </tbody></table> <h4>Data capture</h4> <p>How can a GIS use the information in a map? If the data to be used are not already in digital form, that is, in a form the computer can recognize, various techniques can capture the information. Maps can be digitized by hand-tracing with a computer mouse on the screen or on a digitizing tablet to collect the coordinates of features. Electronic scanners can also convert maps to digits (<span style="color: rgb(0, 0, 102);">fig. 7</span>). Coordinates from Global Positioning System (GPS) receivers can also be uploaded into a GIS (<span style="color: rgb(0, 0, 102);">fig. 8</span>).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure7.jpg" alt="A color photograph showing two women operating a scanner and a computer." border="1" height="278" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 7</span>. Scanning paper maps to produce digital data files for input into a GIS.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure8.jpg" alt="A color photograph showing a man sitting in a field working with GPS receiver." border="1" height="278" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 8</span>. Collecting latitude and longitude coordinates with a Global Positioning System (GPS) receiver.</p> </td> </tr> </tbody></table> <p>A GIS can be used to emphasize the spatial relationships among the objects being mapped. While a computer-aided mapping system may represent a road simply as a line, a GIS may also recognize that road as the boundary between wetland and urban development between two census statistical areas.</p> <p>Data capture—putting the information into the system—involves identifying the objects on the map, their absolute location on the Earth's surface, and their spatial relationships. Software tools that automatically extract features from satellite images or aerial photographs are gradually replacing what has traditionally been a time-consuming capture process. Objects are identified in a series of attribute tables—the "information" part of a GIS. Spatial relationships, such as whether features intersect or whether they are adjacent, are the key to all GIS-based analysis.</p> <h4>Data integration</h4> <p>A GIS makes it possible to link, or integrate, information that is difficult to associate through any other means. Thus, a GIS can use combinations of mapped variables to build and analyze new variables (<span style="color: rgb(0, 0, 102);">fig. 9</span>).</p> <table border="0"> <tbody><tr> <td width="600"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure9.jpg" alt="A color diagram showing how information is processed." border="1" height="311" width="600" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 9</span>. Data integration is the linking of information in different forms through a GIS.</p> </td> </tr> </tbody></table> <p>For example, using GIS technology, it is possible to combine agricultural records with hydrography data to determine which streams will carry certain levels of fertilizer runoff. Agricultural records can indicate how much pesticide has been applied to a parcel of land. By locating these parcels and intersecting them with streams, the GIS can be used to predict the amount of nutrient runoff in each stream. Then as streams converge, the total loads can be calculated downstream where the stream enters a lake.</p><h4>Projection and registration</h4> <p>A property ownership map might be at a different scale than a soils map. Map information in a GIS must be manipulated so that it registers, or fits, with information gathered from other maps. Before the digital data can be analyzed, they may have to undergo other manipulations—projection conversions, for example—that integrate them into a GIS.</p> <p>Projection is a fundamental component of mapmaking. A projection is a mathematical means of transferring information from the Earth's three-dimensional, curved surface to a two-dimensional medium—paper or a computer screen. Different projections are used for different types of maps because each projection is particularly appropriate for certain uses. For example, a projection that accurately represents the shapes of the continents will distort their relative sizes.</p> <p>Since much of the information in a GIS comes from existing maps, a GIS uses the processing power of the computer to transform digital information, gathered from sources with different projections, to a common projection (<span style="color: rgb(0, 0, 102);">figs. 10a and b</span>).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"><p> <img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure10a.jpg" alt="A section of a line map with a color overlay incorrectly aligned with the lines." border="1" height="244" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 10a</span>. An elevation image classified from a satellite image of Minnesota exists in a different scale and projection than the lines on the digital file of the State and province boundaries.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure10b.jpg" alt="A section of a line map with the corrected color overlay." border="1" height="244" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 10b</span>. The elevation image has been reprojected to match the projection and scale of the State and province boundaries</p> </td> </tr> </tbody></table> <h4>Data structures</h4> <p>Can a land use map be related to a satellite image, a timely indicator of land use? Yes, but because digital data are collected and stored in different ways, the two data sources may not be entirely compatible. Therefore, a GIS must be able to convert data from one structure to another.</p> <p>Satellite image data that have been interpreted by a computer to produce a land use map can be "read into" the GIS in raster format. Raster data files consist of rows of uniform cells coded according to data values. An example is land cover classification (<span style="color: rgb(0, 0, 102);">fig. 11</span>). Raster files can be manipulated quickly by the computer, but they are often less detailed and may be less visually appealing than vector data files, which can approximate the appearance of more traditional hand-drafted maps. Vector digital data have been captured as points, lines (a series of point coordinates), or areas (shapes bounded by lines) (<span style="color: rgb(0, 0, 102);">fig. 12</span>). An example of data typically held in a vector file would be the property boundaries for a particular housing subdivision.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure11.gif" alt="A grid of numbers representing raster data." border="1" height="266" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 11</span>. Example of the structure of a raster file.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure12.jpg" alt="A color map showing vector data." border="1" height="266" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 12</span>. Example of the structure of a vector data file.</p> </td> </tr> </tbody></table> <p>Data restructuring can be performed by a GIS to convert data between different formats. For example, a GIS can be used to convert a satellite image map to a vector structure by generating lines around all cells with the same classification, while determining the spatial relationships of the cell, such as adjacency or inclusion (<span style="color: rgb(0, 0, 102);">fig. 13</span>).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure13a.jpg" alt="A color section of a raster map." border="1" height="248" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 13a</span>. Magnified view of the same GIS data file, shown in raster format.</p> </td> <td valign="top" width="300"><p> <img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure13b.jpg" alt="A color diagram of a map in vector format." border="1" height="248" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 13b</span>. Magnified views of the same GIS data file. converted into vector format</p> </td> </tr> </tbody></table> <h4>Data modeling</h4> <p>It is impossible to collect data over every square meter of the Earth's surface. Therefore, samples must be taken at discrete locations. A GIS can be used to depict two- and three-dimensional characteristics of the Earth's surface, subsurface, and atmosphere from points where samples have been collected.</p> <p>For example, a GIS can quickly generate a map with isolines that indicate the pH of soil from test points (<span style="color: rgb(0, 0, 102);">figs. 14 and 15</span>). Such a map can be thought of as a soil pH contour map. Many sophisticated methods can estimate the characteristics of surfaces from a limited number of point measurements. Two- and three-dimensional contour maps created from the surface modeling of sample points from pH measurements can be analyzed together with any other map in a GIS covering the area.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="250"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure14.jpg" alt="A color map section showing points with numbers." border="1" height="374" width="250" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 14</span>. Points with pH values of oil.</p> </td> <td valign="top" width="250"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure15.jpg" alt="A color map showing points and contours." border="1" height="374" width="250" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 15</span>. Contour map made from soil pH values shown in figure 14. </p> </td> </tr> </tbody></table> <a name="special"></a><br /> <span style="font-size:180%;"> <span style="font-weight: bold;">What's Special about GIS?</span></span><br /><p>The way maps and other data have been stored or filed as layers of information in a GIS makes it possible to perform complex analyses.</p> <table align="left" border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="400"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure16.jpg" alt="A color diagram map with cross hairs on a point." border="1" height="267" width="400" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 16</span>. A crosshair pointer can be used to point at a location stored in a GIS. The bottom illustration depicts a computer screen containing the kind of information stored about the location—for example, the latitude, longitude, projection, coordinates, closeness to wells, sources of production, roads, and slopes of land.<br /></p></td> </tr> <tr> <td valign="top" width="400"><br /><p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure16b.jpg" alt="A black and white screen snapshot showing coordinate information for the point." border="1" height="149" width="400" /></p><br /></td> </tr> </tbody></table> <h4>Information retrieval</h4> <p>What do you know about the swampy area at the end of your street? With a GIS you can "point" at a location, object, or area on the screen and retrieve recorded information about it from offscreen files (<span style="color: rgb(0, 0, 102);">fig. 16</span>). Using scanned aerial photographs as a visual guide, you can ask a GIS about the geology or hydrology of the area or even about how close a swamp is to the end of a street. This type of analysis allows you to draw conclusions about the swamp's environmental sensitivity.</p><br /><br /><table align="left" border="0" width="420"> <tbody><tr> <td valign="top" width="400"><br /><p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure17.jpg" alt="A colored section of a map with selected points." border="1" height="267" width="400" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 17</span>. Sources of pollution are represented as points. The colored circles show distance from pollution sources and the wetlands are in dark green.</p> </td> </tr> <tr><td><br /></td></tr> </tbody></table> <h4><br /></h4><h4>Topological modeling</h4> <p>Have there ever been gas stations or factories that operated next to the swamp? Were any of these uphill from and within 2 miles of the swamp? A GIS can recognize and analyze the spatial relationships among mapped phenomena. Conditions of adjacency (what is next to what), containment (what is<br /> enclosed by what), and proximity (how close something is to something else) can be determined with a GIS (<span style="color: rgb(0, 0, 102);">fig. 17</span>).</p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><span style="font-weight: bold;"><br /></span></p><p><br /><span style="font-weight: bold;"></span></p><p><span style="font-weight: bold;"><br />Network</span></p> <p>When nutrients from farmland are running off into streams, it is important to know in which direction the streams flow and which streams empty into other streams. This is done by using a linear network. It allows the computer to determine how the nutrients are transported downstream. Additional information on water volume and speed throughout the spatial network can help the GIS determine how long it will take the nutrients to travel downstream (<span style="color: rgb(0, 0, 102);">figs. 18a and 18b)<br /></span></p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure18a.jpg" alt="A map showing a network lines in blue." border="1" height="350" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 18a</span>. A GIS can simulate the movement of materials along a network of lines. These illustrations show the route of pollutants through a stream system. Flow directions are indicated by arrows.</p> </td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure18b.jpg" alt="A black and white map with a network of blue lines overlaying the map." border="1" height="350" width="300" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 18b</span>. Flow superimposed on a digital orthophoquad of the area</p> </td> </tr> </tbody></table> <h4>Overlay</h4> <p>Using maps of wetlands, slopes, streams, land use, and soils (<span style="color: rgb(0, 0, 102);">figs. 19a-f</span>), the GIS might produce a new map layer or overlay that ranks the wetlands according to their relative sensitivity to damage from nutrient runoff.</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19a.jpg" alt="A black and white shaded relief map with an overlay of colored lines." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19a</span>. Shaded-relief map and contour lines generated from the digital elevation model in the study area.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19b.jpg" alt="A color map of slopes in relief with an overlay of colored lines." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19b</span>. Map showing the steepness of slopes in the study area, created by GIS from the digital elevation model.</p> </td> </tr> <tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19c.jpg" alt="A colored map of streams and buffer zones." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19c</span>. Distances to streams as measured by three 200-meter buffers derived from a digital map of hydrography.</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19d.jpg" alt="A map with colored shapes representing land use." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19d</span>. Map indicating various land uses in the study area.</p> </td> </tr> <tr> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19e.jpg" alt="A map with colors representing various soil types." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19e</span>. A soils map stored in a GIS database. Numbers indicate the type of soil</p> </td> <td valign="top" width="200"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure19f.jpg" alt="A map with colored lines and shapes to represent different zones." border="1" height="267" width="200" /></p> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 19f</span>. The wetlands in the study area ranked according to their vulnerability to pollution on the basis of combination of factors evaluated by GIS</p> </td> </tr> </tbody></table> <h4>Data output</h4> <p>A critical component of a GIS is its ability to produce graphics on the screen or on paper to convey the results of analyses to the people who make decisions about resources. Wall maps, Internet-ready maps, interactive maps, and other graphics can be generated, allowing the decisionmakers to visualize and thereby understand the results of analyses or simulations of potential events (<span style="color: rgb(0, 0, 102);">fig. 20</span>).</p> <table border="0" cellpadding="10" cellspacing="10"> <tbody><tr> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure20b.jpg" alt="A colored satellite photograph modified by GIS." border="1" height="250" width="300" /></p></td> <td valign="top" width="300"> <p><img src="http://erg.usgs.gov/isb/pubs/gis_poster/gisgraphics/figure20a.jpg" alt="A color of a section of a road map." border="1" height="250" width="300" /></p></td> </tr> <tr> <td colspan="2" valign="top" width="600"> <p class="caption"><span style="color: rgb(0, 0, 102);">Figure 20</span>. Examples of finished maps that can be generated using a GIS, showing landforms and geology (left) and human-built and physical features (right).</p> </td> </tr> </tbody></table> <a name="framework"></a> <h3>Framework for cooperation</h3> <p>The use of a GIS can encourage cooperation and communication among the organizations involved in environmental protection, planning, and resource management. The collection of data for a GIS is costly. Data collection can require very specialized computer equipment and technical expertise.</p> <p>Standard data formats ease the exchange of digital information among users of different systems. Standardization helps to stretch data collection funds further by allowing data sharing, and, in many cases, gives users access to data that they could not otherwise collect for economic or technical reasons.<br /></p>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-3511514581788227622007-06-22T11:55:00.000+05:302007-06-22T12:11:14.019+05:30More About GIS<p> </p><h2> What is GIS?</h2> <a href="http://www.gis.com/whatisgis/graphics/mainpage.jpg" target="_blank"><img src="http://www.gis.com/whatisgis/graphics/mainpage_sm.jpg" alt="" align="left" border="0" height="155" hspace="10" width="153" /></a> <p class="execCaption" style="padding-top: 10px;">GIS is a collection of computer hardware, software, and geographic data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.<br /> </p> <br /><br /> <div class="execDotted" style="padding-top: 10px;"> </div> <h3> Why Geography?</h3> <p><span style="text-decoration: underline;">Geography</span> is a serious <span style="text-decoration: underline;">discipline</span> with multibillion dollar implications for businesses and governments. Choosing sites, targeting market segments, planning distribution networks, responding to emergencies, or redrawing country boundaries—all of these problems involve questions of geography.</p> <p><a href="http://www.esri.com/mapmuseum/mapbook_gallery/volume20/business2.html" target="_blank"><img src="http://www.gis.com/whatisgis/graphics/bofa.jpg" alt="Network Map for Bank of America" style="margin-left: 10px; margin-top: 5px;" align="right" border="0" /></a><span style="text-decoration: underline;">Here's an example how Bank of America used GIS </span>to show the geographic distribution of the bank's network in relation to deposit potential in the New York City market area. From this analysis, Bank of America can determine where their coverage is strong and where it is weak. Red dots symbolize strong coverage; no dots means coverage is nonexistent.<br /></p> <br /><p><br /></p><p> <span style="font-size:130%;"><span style="font-weight: bold;">How Does GIS Use Geography?</span></span></p> <p>With a geographic information system (GIS), you can link information (attributes) to location data, such as people to addresses, buildings to parcels, or streets within a network. You can then layer that information to give you a better understanding of how it all works together. You choose what layers to combine based on what questions you need to answer.</p> <a href="http://www.esri.com/mapmuseum/mapbook_gallery/volume20/safety3.html" target="_blank"><img src="http://www.gis.com/whatisgis/graphics/safety.jpg" alt="Map of EMS Travel Times" style="margin-left: 10px; margin-top: 5px;" align="right" border="0" /></a><span style="text-decoration: underline;">In this example,</span> emergency medical service (EMS) call information, including call type, elapsed travel time, and which rescue unit was dispatched to the call's location, has been linked to addresses. With this GIS-linked database, questions such as "What percent of dispatched calls did each EMS unit respond to within its assigned zone?" can be answered.<br /><br /><h3> Three Views of a GIS</h3> <p>A GIS is most often associated with maps. A map, however, is only one way you can work with geographic data in a GIS, and only one type of product generated by a GIS. This is important, because it means that <b>a GIS can provide a great deal more problem-solving capabilities than using a simple mapping program or adding data to an online mapping tool (creating a "mash-up")</b>. </p> <p>A GIS can be viewed in three ways: </p> <!--<p>GIS technology can be integrated into an organization's enterprise information system framework.</p> --> <ol><li><b><span style="color: rgb(255, 0, 0);">The Database View</span>:</b> A GIS is a unique kind of database of the world—a geographic database (<b style="color: rgb(51, 102, 255);">geodatabase</b>). It is an "Information System for Geography." Fundamentally, a GIS is based on a structured database that describes the world in geographic terms. <a href="http://www.esri.com/software/arcgis/concepts/gis-data.html" target="_blank"><img src="http://www.gis.com/graphics/orangearrow.gif" alt="" style="margin-top: 4px;" border="0" height="10" width="24" /></a><br /><br /> <img src="http://www.gis.com/whatisgis/graphics/addressfinal.gif" alt="Example of geodata showing tabular address data related to a street map." height="128" hspace="30" vspace="15" width="282" /></li><li><b style="color: rgb(255, 0, 0);">The Map View:</b> A GIS is a set of intelligent maps and other views that show features and feature relationships on the earth's surface. Maps of the underlying geographic information can be constructed and used as "windows into the database" to support queries, analysis, and editing of the information. This is called <b style="color: rgb(51, 102, 255);">geovisualization</b>.<br /><br /> <table> <tbody><tr valign="middle"> <td><img src="http://www.gis.com/whatisgis/graphics/geovis1.jpg" alt="" border="0" height="149" hspace="15" vspace="15" width="205" /></td> <td><img src="http://www.gis.com/whatisgis/graphics/geovis2.gif" alt="" border="0" height="143" hspace="5" width="101" /></td> </tr> </tbody></table> </li><li><b style="color: rgb(255, 0, 0);">The Model View:</b> A GIS is a set of information transformation tools that derive new geographic datasets from existing datasets. These <b style="color: rgb(51, 102, 255);">geoprocessing</b><span style="color: rgb(51, 102, 255);"> </span>functions take information from existing datasets, apply analytic functions, and write results into new derived datasets.<br /> <br /><img src="http://www.gis.com/whatisgis/graphics/modellg.jpg" alt="Example of a model or process flow, with datasets, functions, and results." height="130" vspace="20" width="390" /> </li></ol> <p>In other words, by combining data and applying some analytic rules, you can create a model that helps answer the question you have posed. In the example below, GPS and GIS were used to accurately model the expected location and distribution of debris for the <i>Space Shuttle Columbia</i>, which broke up upon re-entry over eastern Texas on February 1, 2003. <a href="http://www.esri.com/mapmuseum/mapbook_gallery/volume19/cartography1.html" target="_blank"><br /></a><br /></p> <p><a href="http://www.esri.com/mapmuseum/mapbook_gallery/volume19/cartography1.html" target="_blank"><img src="http://www.gis.com/whatisgis/graphics/columbia.jpg" border="0" height="134" width="438" /></a></p> <p>Together, these three views are critical parts of an intelligent GIS and are used at varying levels in all GIS applications. </p> <!--end content--><!--text navigation, copyright, date-->Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-69762007607925514942007-06-20T10:52:00.000+05:302007-06-20T10:53:07.419+05:30<h3 align="center">Glossary of GPS Terms</h3><b> <p align="center">- A -</p></b> <p><b>Almanac -</b> the Almanac is a file which contains positional information for all of the GPS satellites. The Almanac is used by the GPS receiver to determine which satellites to track, and can also be used for mission planning. </p> <p><b>Attribute -</b> a characteristic which describes a Feature. Attributes can be thought of as questions which are asked about the Feature. </p> <p align="center"><br /><b>- C -</b><br /></p> <p><b>C/A Code -</b> the standard (Course/Acquisition) GPS code used by most GIS level GPS receivers. Also known as the civilian code. </p> <p><b>Carrier -</b> the signal that carries the C/A Code from the satellite to the GPS receiver. </p> <p><b>Carrier-aided Tracking -</b> a signal processing technique that uses the GPS carrier signal to achieve an exact lock on the pseudo random code generated by the GPS satellite. Carrier-aided tracking is more accurate than standard C/A Code tracking. </p> <p><b>Channel -</b> a channel of a GPS receiver consists of the circuitry necessary to track the signal from a single GPS satellite. </p> <p><b>Cycle Slip -</b> a loss of continuity in the measured carrier beat phase which results from a temporary loss of lock on a GPS satellite. </p> <p align="center"><br /><b>- D -</b><br /></p> <b> </b><p><b>Differential Correction - </b>the technique of comparing GPS data collected in the field to GPS data collected at a known point. By collecting GPS data at a known point, a correction factor can be determined and applied to the field GPS data. </p> <p><b>Dilution of Precision</b> <b>(DOP) -</b> an indicator of satellite geometry for a unique constellation of satellites used to determine a position. Positions tagged with a higher DOP value generally constitute poorer measurement results than those tagged with lower DOP. </p> <p><b>Dynamic Positioning -</b> the process of collecting GPS data while the GPS antenna is in motion. Often associated with Line or Area Features. </p> <p align="center"><br /><b>- E -</b><br /></p> <p><b>Ephemeris -</b> the predicted changes in the orbit of a satellite that are transmitted to the GPS receiver from the individual satellites. </p> <p><b>Ephemeris Errors -</b> errors which originate in the ephemeris data transmitted by a GPS satellite. Ephemeris errors are removed by differential correction. </p> <p align="center"><br /><b>- F -</b><br /></p> <p><b>Feature -</b> the object which is being mapped for use in a GIS system. Features may be points, lines or areas. </p> <p><b>Featuring -</b> the process of collecting GPS and GIS information simultaneously. </p> <p align="center"><br /><b>- G -</b><br /></p> <p><b>Geographic Information System (GIS) - </b>a mapping system which combines positional data with descriptive information to form a layered map. </p> <p><b>Global Positioning System (GPS)</b> - a system for providing precise location which is based on data transmitted from a constellation of 24 satellites </p> <p align="center"><br /><b>- L -</b><br /></p> <p><b>L-band -</b> the group of radio frequencies which carry the GPS data from the satellites to the GPS receivers. </p> <p align="center"><br /><b>- M -</b><br /></p> <p><b>Multipath - </b>the interference to a signal that has reached the receiver antenna by multiple paths; usually caused by the signal being bounced or reflected. Signals from satellites low on the horizon will have high multipath error. Receivers that can be configured to "mask out" signals from such satellites can help minimize multi-path. </p> <p align="center"><br /><b>- P -</b><br /></p> <p><b>Pseudorange -</b> an uncorrected measurement of the distance between a GPS satellite and a GPS receiver determined by comparing a code transmitted by the satellite to a code generated by the receiver. </p> <p align="center"><br /><b>- R -</b><br /></p> <p><b>Residual -</b> a quality indicator for a GPS position that is determined during the differential correction process. Indicates uncorrectable error. High residuals are not desirable. </p> <p align="center"><br /><b>- S -</b><br /></p> <p><b>Satellite Constellation</b> <b>- </b>the group of GPS satellites from which data is used to determine a position. </p> <p><b>Static Positioning -</b> the process of averaging GPS positions taken successively over a period of time with a stationary antenna to increase accuracy. </p> <p align="center"><br /><b>- V -</b><br /></p> <p><b>Value -</b> descriptive information about a Feature. Values can be thought of as the answers to the questions posed by Attributes. </p>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-26391588029374675312007-06-20T10:35:00.000+05:302007-06-20T10:51:28.226+05:30GLOBAL POSITIONING SYSTEM (GPS)<h3 style="font-family: trebuchet ms;" align="center">What is GPS?</h3><p>The Global Positioning System (GPS) is a location system based on a constellation of about 24 satellites orbiting the earth at altitudes of approximately 11,000 miles. GPS was developed by the United States Department of Defense (DOD), for its tremendous application as a military locating utility. The DOD's investment in GPS is immense. Billions and billions of dollars have been invested in creating this technology for military uses. However, over the past several years, GPS has proven to be a useful tool in non-military mapping applications as well. </p> <p>GPS satellites are orbited high enough to avoid the problems associated with land based systems, yet can provide accurate positioning 24 hours a day, anywhere in the world. Uncorrected positions determined from GPS satellite signals produce accuracies in the range of 50 to 100 meters. When using a technique called differential correction, users can get positions accurate to within 5 meters or less. </p> <p>Today, many industries are leveraging off the DOD's massive undertaking. As GPS units are becoming smaller and less expensive, there are an expanding number of applications for GPS. In transportation applications, GPS assists pilots and drivers in pinpointing their locations and avoiding collisions. Farmers can use GPS to guide equipment and control accurate distribution of fertilizers and other chemicals. Recreationally, GPS is used for providing accurate locations and as a navigation tool for hikers, hunters and boaters. </p> <p>Many would argue that GPS has found its greatest utility in the field of Geographic Information Systems (GIS). With some consideration for error, GPS can provide any point on earth with a unique address (its precise location). A GIS is basically a descriptive database of the earth (or a specific part of the earth). GPS tells you that you are at point X,Y,Z while GIS tells you that X,Y,Z is an oak tree, or a spot in a stream with a pH level of 5.4. GPS tells us the "where". GIS tells us the "what". GPS/GIS is reshaping the way we locate, organize, analyze and map our resources. </p><br /><h3 style="font-family: trebuchet ms;" align="center">Trilateration - How GPS Determines Location</h3><br /><p>In a nutshell, GPS is based on satellite ranging - calculating the distances between the receiver and the position of 3 or more satellites (4 or more if elevation is desired) and then applying some good old mathematics. Assuming the positions of the satellites are known, the location of the receiver can be calculated by determining the distance from each of the satellites to the receiver. GPS takes these 3 or more known references and measured distances and "triangulates" an additional position. </p> <p>As an example, assume that I have asked you to find me at a stationary position based upon a few clues which I am willing to give you. First, I tell you that I am exactly 10 miles away from your house. You would know I am somewhere on the perimeter of a sphere that has an origin as your house and a radius of 10 miles. With this information alone, you would have a difficult time to find me since there are an infinite number of locations on the perimeter of that sphere. </p> <p>Second, I tell you that I am also exactly 12 miles away from the ABC Grocery Store. Now you can define a second sphere with its origin at the store and a radius of 12 miles. You know that I am located somewhere in the space where the perimeters of these two spheres intersect - but there are still many possibilities to define my location. </p> <p>Adding additional spheres will further reduce the number of possible locations. In fact, a third origin and distance (I tell you am 8 miles away from the City Clock) narrows my position down to just 2 points. By adding one more sphere, you can pinpoint my exact location. Actually, the 4th sphere may not be necessary. One of the possibilities may not make sense, and therefore can be eliminated. </p> <p>For example, if you know I am above sea level, you can reject a point that has negative elevation. Mathematics and computers allow us to determine the correct point with only 3 satellites. </p> <p align="center"><img src="http://www.cmtinc.com/gpsbook/trilat2.gif" alt="" height="262" width="323" /> </p> <p>Based on this example, you can see that you need to know the following information in order to compute your position: </p> <blockquote> <p>A) What is the precise location of three or more known points (GPS satellites)?<br />B) What is the distance between the known points and the position of the GPS receiver?</p><p><br /></p><h3 style="font-family: trebuchet ms;" align="center"> How the Current Locations of GPS Satellites are Determined</h3> <p>GPS satellites are orbiting the Earth at an altitude of 11,000 miles. The DOD can predict the paths of the satellites vs. time with great accuracy. Furthermore, the satellites can be periodically adjusted by huge land-based radar systems. Therefore, the orbits, and thus the locations of the satellites, are known in advance. Today's GPS receivers store this orbit information for all of the GPS satellites in what is known as an <b>almanac</b>. Think of the almanac as a "bus schedule" advising you of where each satellite will be at a particular time. Each GPS satellite continually broadcasts the almanac. Your GPS receiver will automatically collect this information and store it for future reference. </p> <p>The Department of Defense constantly monitors the orbit of the satellites looking for deviations from predicted values. Any deviations (caused by natural atmospheric phenomenon such as gravity), are known as <b>ephemeris</b><i> </i>errors. When ephemeris errors are determined to exist for a satellite, the errors are sent back up to that satellite, which in turn broadcasts the errors as part of the standard message, supplying this information to the GPS receivers. </p> <p>By using the information from the almanac in conjuction with the ephemeris error data, the position of a GPS satellite can be very precisely determined for a given time. </p> <p><br /></p> <hr noshade="noshade"> <p><a name="chap4"></a></p> <h3 style="font-family: trebuchet ms;" align="center"> Computing the Distance Between Your Position and the GPS Satellites</h3> <p>GPS determines distance between a GPS satellite and a GPS receiver by measuring the amount of time it takes a radio signal (the GPS signal) to travel from the satellite to the receiver. Radio waves travel at the speed of light, which is about 186,000 miles per second. So, if the amount of time it takes for the signal to travel from the satellite to the receiver is known, the distance from the satellite to the receiver (distance = speed x time) can be determined. If the exact time when the signal was transmitted and the exact time when it was received are known, the signal's travel time can be determined. </p> <p>In order to do this, the satellites and the receivers use very accurate clocks which are synchronized so that they generate the same code at exactly the same time. The code received from the satellite can be compared with the code generated by the receiver. By comparing the codes, the time difference between when the satellite generated the code and when the receiver generated the code can be determined. This interval is the travel time of the code. Multiplying this travel time, in seconds, by 186,000 miles per second gives the distance from the receiver position to the satellite in miles. </p> </blockquote><br /><h3 style="font-family: trebuchet ms;" align="center">Four (4) Satellites to give a 3D </h3><h3 style="font-family: trebuchet ms;" align="center">position</h3><br /><p>In the previous example, you saw that it took only 3 measurements to "triangulate" a 3D position. However, GPS needs a 4th satellite to provide a 3D position. Why?? </p> <p>Three measurements can be used to locate a point, assuming the GPS receiver and satellite clocks are precisely and continually synchronized, thereby allowing the distance calculations to be accurately determined. Unfortunately, it is impossible to synchronize these two clocks, since the clocks in GPS receivers are not as accurate as the very precise and expensive atomic clocks in the satellites. The GPS signals travel from the satellite to the receiver very fast, so if the two clocks are off by only a small fraction, the determined position data may be considerably distorted. </p> <p>The atomic clocks aboard the satellites maintain their time to a very high degree of accuracy. However, there will always be a slight variation in clock rates from satellite to satellite. Close monitoring of the clock of each satellite from the ground permits the control station to insert a message in the signal of each satellite which precisely describes the drift rate of that satellite's clock. The insertion of the drift rate effectively synchronizes all of the GPS satellite clocks. </p> <p>The same procedure cannot be applied to the clock in a GPS receiver। Therefore, a fourth variable (in addition to x, y and z), time, must be determined in order to calculate a precise location. Mathematically, to solve for four unknowns (x,y,z, and t), there must be four equations. In determining GPS positions, the four equations are represented by signals from four different satellites.<br /></p><br /><h3 style="font-family: trebuchet ms;" align="center"> GPS Error Budget</h3> <p>The GPS system has been designed to be as nearly accurate as possible. However, there are still errors. Added together, these errors can cause a deviation of <b>+/- 50 -100</b> meters from the actual GPS receiver position. There are several sources for these errors, the most significant of which are discussed below: </p> <h4>Atmospheric Conditions</h4> <p>The ionosphere and troposphere both refract the GPS signals. This causes the speed of the GPS signal in the ionosphere and troposphere to be different from the speed of the GPS signal in space. Therefore, the distance calculated from "Signal Speed x Time" will be different for the portion of the GPS signal path that passes through the ionosphere and troposphere and for the portion that passes through space. </p> <h4>Ephemeris Errors/Clock Drift/Measurement Noise</h4> <p>As mentioned earlier, GPS signals contain information about ephemeris (orbital position) errors, and about the rate of clock drift for the broadcasting satellite. The data concerning ephemeris errors may not exactly model the true satellite motion or the exact rate of clock drift. Distortion of the signal by measurement noise can further increase positional error. The disparity in ephemeris data can introduce 1-5 meters of positional error, clock drift disparity can introduce 0-1.5 meters of positional error and measurement noise can introduce 0-10 meters of positional error. </p> <h4>Selective Availability</h4> <p>Ephemeris errors should not be confused with Selective Availability (SA), which is the intentional alteration of the time and epherimis signal by the Department of Defense. SA can introduce 0-70 meters of positional error. Fortunately, positional errors caused by SA can be removed by differential correction. </p> <h4>Multipath</h4> <p>A GPS signal bouncing off a reflective surface prior to reaching the GPS receiver antenna is referred to as multipath. Because it is difficult to completely correct multipath error, even in high precision GPS units, multipath error is a serious concern to the GPS user. </p> <p>The chart below lists the most common sources of error in GPS positions. This chart is commonly known as the GPS Error Budget: </p> <h4>GPS Error Budget</h4> <pre style="color: rgb(51, 102, 255); font-weight: bold;">Source Uncorrected Error Level<br />Ionosphere 0-30 meters<br />Troposphere 0-30 meters<br />Measurement Noise 0-10 meters<br />Ephemeris Data 1-5 meters<br />Clock Drift 0-1.5 meters<br />Multipath 0-1 meter<br />Selective Availability 0-70 meters<br /></pre><br /><h3 style="font-family: trebuchet ms;" align="center">Measuring GPS Accuracy</h3><br /><p>As discussed above, there are several external sources which introduce errors into a GPS position. While the errors discussed above always affect accuracy, another major factor in determining positional accuracy is the alignment, or geometry, of the group of satellites (constellation) from which signals are being received. The geometry of the constellation is evaluated for several factors, all of which fall into the category of Dilution Of Precision, or DOP. </p> <h4>DOP</h4> <p>DOP is an indicator of the quality of the geometry of the satellite constellation. Your computed position can vary depending on which satellites you use for the measurement. Different satellite geometries can magnify or lessen the errors in the error budget described above. A greater angle between the satellites lowers the DOP, and provides a better measurement. A higher DOP indicates poor satellite geometry, and an inferior measurement cofiguration. </p> <p align="center"><img src="http://www.cmtinc.com/gpsbook/gooddops.gif" height="266" width="356" /><br /><img src="http://www.cmtinc.com/gpsbook/baddops.gif" height="266" width="356" /><br /></p> <p>Some GPS receivers can analyze the positions of the satellites available, based upon the almanac, and choose those satellites with the best geometry in order to make the DOP as low as possible। Another important GPS receiver feature is to be able to ignore or eliminate GPS readings with DOP values that exceed user-defined limits. Other GPS receivers may have the ability to use all of the satellites in view, thus minimizing the DOP as much as possible.<br /></p><br /><h3 style="font-family: trebuchet ms;" align="center">Using Differential GPS to Increase Accuracy</h3><p>As powerful as GPS is, +/-50 - 100 meters of uncertainty is not acceptable in many applications. How can we obtain higher accuracies? </p> <p>A technique called <b>differential correction </b>is necessary to get accuracies within 1 -5 meters, or even better, with advanced equipment. Differential correction requires a second GPS receiver, a<i> base station, </i>collecting data at a stationary position on a precisely known point (typically it is a surveyed benchmark). Because the physical location of the base station is known, a correction factor can be computed by comparing the known location with the GPS location determined by using the satellites. </p> <p>The differential correction process takes this correction factor and applies it to the GPS data collected by a GPS receiver in the field. Differential correction eliminates most of the errors listed in the GPS Error Budget discussed earlier. After differential correction, the GPS Error Budget changes as follows: </p> <h4>GPS Error Budget</h4> <pre><span style="color: rgb(51, 102, 255); font-weight: bold;">Source Uncorrected With Differential</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Ionosphere 0-30 meters Mostly Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Troposphere 0-30 meters All Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Signal Noise 0-10 meters All Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Ephemeris Data 1-5 meters All Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Clock Drift 0-1.5 meters All Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">Multipath 0-1 meters Not Removed</span><br /><span style="color: rgb(51, 102, 255); font-weight: bold;">SA 0-70 meters All Removed</span><br /></pre> <p>By eliminating many of the above errors, differential correction allows GPS positions to be computed at a much higher level of accuracy.</p><p><br /></p><br /><h3 style="font-family: trebuchet ms;" align="center">Levels of GPS Accuracy</h3><p>There are three types of GPS receivers which are available in today's marketplace. Each of the three types offers different levels of accuracy, and has different requirements to obtain those accuracies. To this point, the discussion in this book has focused on Coarse Acquisition (C/A code) GPS receivers. The two remaining types of GPS receiver are Carrier Phase receivers and Dual Frequency receivers. </p> <h4>C/A Code receivers</h4> <p>C/A Code receivers typically provide 1-5 meter GPS position accuracy with differential correction. C/A Code GPS receivers provide a sufficient degree of accuracy to make them useful in most GIS applications. </p> <p>C/A Code receivers can provide 1-5 meter GPS position accuracy with an occupation time of 1 second. Longer occupation times (up to 3 minutes) will provide GPS position accuracies consistently within 1-3 meters. Recent advances in GPS receiver design will now allow a C/A Code receiver to provide sub-meter accuracy, down to 30 cm. </p> <h4>Carrier Phase receivers</h4> <p>Carrier Phase receivers typically provide 10-30 cm GPS position accuracy with differential correction. Carrier Phase receivers provide the higher level of accuracy demanded by certain GIS applications. </p> <p>Carrier Phase receivers measure the distance from the receiver to the satellites by counting the number of waves that carry the C/A Code signal. This method of determining position is much more accurate; however, it does require a substatially higher occupation time to attain 10-30 cm accuracy. Initializing a Carrier Phase GPS job on a known point requires an occupation time of about 5 minutes. Initializing a Carrier Phase GPS job on an unknown point requires an occupation time of about 30-40 minutes. </p> <p>Additional requirements, such as maintaining the same satellite constellation throughout the job, performance under canopy and the need to be very close to a base station, limit the applicability of Carrier Phase GPS receivers to many GIS applications. </p> <h4>Dual-Frequency receivers</h4> <p>Dual-Frequency receivers are capable of providing sub-centimeter GPS position accuracy with differential correction. Dual-Frequency receivers provide "survey grade" accuracies not often required for GIS applications. </p> <p>Dual-Frequency receivers receive signals from the satellites on two frequencies simultaneously। Receiving GPS signals on two frequencies simultaneously allows the receiver to determine very precise positions.<br /></p><br /><h3 style="font-family: trebuchet ms;" align="center">GPS and Canopy</h3><br /><p>GPS receivers require a line of sight to the satellites in order to obtain a signal representative of the true distance from the satellite to the receiver. Therefore, any object in the path of the signal has the potential to interfere with the reception of that signal. Objects which can block a GPS signal include tree canopy, buildings and terrain features. </p> <p>Further, reflective surfaces can cause the GPS signals to bounce before arriving at a receiver, thus causing an error in the distance calculation. This problem, known as multipath, can be caused by a variety of materials including water, glass and metal. The water contained in the leaves of vegatation can produce multipath error. In some instances, operating under heavy, wet forest canopy can degrade the ability of a GPS receiver to track satellites. </p> <p>There are several data collection techniques which can mitigate the effects of signal blockage by tree canopy or other objects. For example, many GPS receivers can be instructed to track only the highest satellites in the sky, as opposed to those satellites which provide the best DOP. Increasing the elevation of the GPS antenna can also dramatically increase the ability of the receiver to track satellites. </p> <p>Unfortunately, there will be locations where GPS signals simply are not available due to obstruction. In these cases, there are additional techniques which can help to solve the problem. Some GPS receivers have the ability to collect an offset point, which involves recording a GPS position at a location where GPS signals are available while also recording the distance, bearing and slope from the GPS antenna to the position of interest where the GPS signals are not available. This technique is useful for avoiding a dense timber stand or building. </p> Further, a traditional traverse program can be used to manually enter a series of bearings and ranges to generate positions until satellite signals can again be received. This position data can then be used to augment position data collected with the GPS receiver.<br /><br /><br /><br /><h3 style="font-family: trebuchet ms;" align="center">GPS for GIS</h3><br /><p>Up to this point, the discussion has focused on describing how GPS determines a location on the surface of the Earth. Now the discussion can shift to the process of describing what is at the location. The "what" is the object or objects which will be mapped. These objects are referred to as "Features", and are used to build a GIS. It is the power of GPS to precisely locate these Features which adds so much to the utility of the GIS system. On the other hand, without Feature data, a coordinate location is of little value. </p> <h4>Feature Types</h4> <p>There are three types of Feature which can be mapped: Points, Lines and Areas. A Point Feature is a single GPS coordinate position which is identified with a specific Object. A Line Feature is a collection of GPS positions which are identified with the same Object and linked together to form a line. An Area Feature is very similar to a Line Feature, except that the ends of the line are tied to each other to form a closed area. </p> <h4>Describing Features</h4> <p>As stated above, a Feature is the object which will be mapped by the GPS system. The ability to describe a Feature in terms of a multi-layered database is essential for successful integration with any GIS system. For example, it is possible to map the location of each house on a city block and simply label each coordinate position as a house. However, the addition of information such as color, size, cost, occupants, etc. will provide the ability to sort and classify the houses by these catagories. </p> <p>These catagories of descriptions for a Feature are know as Attributes. Attributes can be thought of as questions which are asked about the Feature. Using the example above, the Attributes of the Feature "house" would be "color", "size", "cost" and "occupants". </p> <p>Logically, each question asked by the Attributes must have an answer. The answers to the questions posed by the Attributes are called Values. In the example above, an appropriate Value (answer) for the Attribute (question) "color" may be "blue". </p> <p>The following table illustrates the relationship between Features, Attributes and Values: </p> <pre><span style="font-weight: bold; color: rgb(51, 102, 255);">Feature Attribute Value</span><br /><span style="font-weight: bold; color: rgb(51, 102, 255);">House Color Blue</span><br /><span style="font-weight: bold; color: rgb(51, 102, 255);"> Size 3 BDR</span><br /><span style="font-weight: bold; color: rgb(51, 102, 255);"> Cost $118K</span><br /><span style="font-weight: bold; color: rgb(51, 102, 255);"> Occupants 5</span><br /></pre> <p>By collecting the same type of data for each house which is mapped, a database is created. Tying this database to position information is the core philosophy underlying any GIS system. </p> <h4>Feature Lists</h4> <p>The field data entry process can be streamlined by the use of a Feature List. The Feature List is a database which contains a listing of the Features which will be mapped, as well as the associated Attributes for each Feature. In addition, the Feature List contains a selection of appropriate Values for each Attribute. The Feature List can be created on the CMT hand-held GPS data collector, or on a PC. Below is an example of a Feature List as it appears in <a href="http://www.cmtinc.com/software/index.htm#pcgps">PC-GPS</a>: </p> <p>When a Feature List is used in the field, the first step is to select the Feature to be mapped. Once a Feature is selected, the Attributes for that Feature are automatically listed. A Value for each Attribute can then be selected from the displayed list of predetermined Values. </p> <p>The use of a Feature List streamlines the data entry process and also ensures consistent data entry among different users in the same organization. </p> <h4>Exporting to a GIS System</h4> <p>The final step in incorporating GPS data with a GIS system is to export the GPS and Feature data into the GIS system. During this process, a GIS "layer" is created for each Feature in the GPS job. For example, the process of exporting a GPS job which contains data for House, Road and Lot Features would create a House layer, a Road layer and a Lot layer in the GIS system. These layers can then be incorporated with existing GIS data. </p> <p>Once the GPS job has been exported, the full power of the GIS system can be used to classify and evaluate the data.<br /></p><br /><p><br /></p><p><br /></p><p> </p>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0tag:blogger.com,1999:blog-8475609323986890502.post-60024091775317374702007-06-16T21:59:00.001+05:302007-06-16T22:13:01.753+05:30<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwilCb9YPJogjDFiJ9SMh_a5zBK_FfKshvtjqG0DJXkco8SbeVlGz2ZZ32v4TLYm5rHY6f2KHb7OiNqFUmf94RBCSNEQuoi4nGNU7kL9UEHHGCUgFHUWOSRg9W_M1JiiVzNX2JhV8-tNvM/s1600-h/5+Points+of+GIS.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwilCb9YPJogjDFiJ9SMh_a5zBK_FfKshvtjqG0DJXkco8SbeVlGz2ZZ32v4TLYm5rHY6f2KHb7OiNqFUmf94RBCSNEQuoi4nGNU7kL9UEHHGCUgFHUWOSRg9W_M1JiiVzNX2JhV8-tNvM/s320/5+Points+of+GIS.jpg" alt="" id="BLOGGER_PHOTO_ID_5076702855604737634" border="0" /></a><span style="font-size:100%;"><br /></span><span class="title" style="font-size:100%;"><span class="subTitle">WHAT IS G.I.S.</span></span><span startcont="this" class="subTitle" style="font-size:100%;"> </span><span style="font-size:100%;"><br /></span><p align="left"> <span style="color: rgb(0, 0, 128);font-family:Castellar;font-size:100%;" >T</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >he term GIS might be new to many in these parts so we would like to briefly explain what it is. GIS stands for </span> <span style="color: rgb(0, 0, 128);font-family:Arial;font-size:100%;" > G</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >eographic </span> <span style="color: rgb(0, 0, 128);font-family:Arial;font-size:100%;" > I</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >nformation </span> <span style="color: rgb(0, 0, 128);font-family:Arial;font-size:100%;" > S</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >ystems. A GIS stores all the features you might find on a map such as roads, buildings, manholes, parks, and city boundarys. These features are stored as points, lines, polygons (areas), and cells (image pixels) in a computer. We put all the similar features into categories called themes, which are stacked on top of each other to form the map that is displayed and printed. The GIS also stores information about each feature such as road surface material, park name, parcel number, owner name, and census population figure in a database. The digital features and database are tied together so that a person can perform analysis on the map features. You can now ask; Where is it? What is it? What spatial patterns exist? What has changed since...? What if...? How many have…? </span> </p><p align="left"> <span style="color: rgb(0, 0, 128);font-family:Castellar;font-size:100%;" >S</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >ince information on each features actual location is stored, a GIS also allows you to perform spatial analysis, which means you can overlay flood plains on top of parcels and generate a list of all landowners within the flood plain. You can find out how many people live within 500 feet of a feature or how many feet of water pipes have been constructed in corrosive soil zones. </span> </p><p align="left"> <span style="color: rgb(0, 0, 128);font-family:Castellar;font-size:100%;" >T</span><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" >he GIS technology as a whole consists of trained staff, software, hardware, large format plotters, GPS (Global Positioning Systems), digital data, relational databases, orthophotography (corrected aerial photography), and much more।</span></p><p align="left"><span style="color: rgb(51, 51, 51);font-family:Arial;font-size:100%;" ><br /></span></p><p><strong> GIS</strong>- Graphic Information System </p> <p><img src="http://www2.grand-forks.k12.nd.us/hs/projects/rr/tsa/TSA%20Website/GIS.jpg" height="351" width="473" /></p> <!-- image from www.colorado.edu --> <p><strong>History of Development </strong></p> <p><strong>-</strong>Developed by Roger Tomlinson, it was called "Canadian GIS" (CGIS) and was used to store, analyze and manipulate data collected for the Canada Land Inventory (CLI)</p> <p><strong>-</strong> CGIS was the world's first "system" and was an improvement over "mapping" applications as it provided capabilities for overlay, measurement, & digitizing/scanning.</p> <p><strong>-</strong> CGIS lasted into the 1990s and built the largest digital land resource data base in Canada.</p> <p>-By the end of the 20th century, the rapid growth in various systems had been consolidated and standardized on relatively few platforms and users were beginning to export the concept of viewing GIS data over the Internet, requiring data format and transfer standards.</p> <p><strong>Techniques used in GIS </strong></p> <p>-GIS can also convert existing digital information, which may not yet be in map form, into forms it can recognize and use.</p> <p><strong> Data Capture Types </strong></p> <p><strong>-</strong>Existing data printed on paper or PET film maps can be digitized or scanned to produce digital data.</p> <p>Survey data can be directly entered into a GIS from digital data collection systems on survey instruments.</p> <p>-Remotely sensed data also plays an important role in data collection and consist of sensors attached to a platform.</p> <p><strong>Open Source </strong></p> <p><strong>-</strong>Google Maps<strong></strong>is free and open source, while being able to interact with other maps.</p> <p><img src="http://www2.grand-forks.k12.nd.us/hs/projects/rr/tsa/TSA%20Website/Google_Maps_tokyo.jpg" height="336" width="434" /></p> <p>-The use of open-source software is not new, and for a time provided arguably the best GIS available. GRASS GIS is probably the most well-known of these systems.</p> <p>-GRASS is currently used in academic and commercial settings around the world, as well as many governmental agencies including NASA, NOAA, USDA, DLR, CSIRO, the National Park Service, the U.S. Census Bureau, USGS, and many environmental consulting companies.</p> <p> </p>Vishalhttp://www.blogger.com/profile/11716703624354184670noreply@blogger.com0