16 June 2007


The term GIS might be new to many in these parts so we would like to briefly explain what it is. GIS stands for Geographic Information Systems. 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…?

Since 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.

The 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।

GIS- Graphic Information System

History of Development

-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)

- CGIS was the world's first "system" and was an improvement over "mapping" applications as it provided capabilities for overlay, measurement, & digitizing/scanning.

- CGIS lasted into the 1990s and built the largest digital land resource data base in Canada.

-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.

Techniques used in GIS

-GIS can also convert existing digital information, which may not yet be in map form, into forms it can recognize and use.

Data Capture Types

-Existing data printed on paper or PET film maps can be digitized or scanned to produce digital data.

Survey data can be directly entered into a GIS from digital data collection systems on survey instruments.

-Remotely sensed data also plays an important role in data collection and consist of sensors attached to a platform.

Open Source

-Google Mapsis free and open source, while being able to interact with other maps.

-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.

-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.