EESC 3750 - Geographic Information Systems: GIS

“All tools are designed to meet a certain need. Sharp things are for cutting, hard things are for hammering and pointing things for binding things together. GIS is also a tool. Geographers, who needed a tool (more like a toolkit) to answer geographic questions, were the primary designers of the original GIS software. Today, many disciplines have contributed enormously to this growing field, but the questions GIS is designed to answer remain fundamentally geographic ones,” (DeMers 2009).

A Geographic Information System is a computer-based set of hardware and software used to capture analyze, manipulate and visualize information. A GIS can organize and display both spatial data and non-spatial data, such as the location of hospitals (spatial) and the number of patients treated for Lyme disease at that location (non-spatial). A GIS can capture, create, manipulate, analyze, visualize, and store information in a map format.

Some of the tasks that a GIS can do:

• Identify patterns and retrieve information from maps
• Count, group, classify, reclassify, isolate, measure and quantify map features
• Overlay maps to compare features and create new maps
• Visualize, interpolate, slice, cross-section, sample and generalize surfaces
• Identify the shortest or fastest travel path between points
• Perform topographic and other feature analyses

Better said, a GIS is a model of data in a computer environment that can be analyzed using the computer processor. Why is it a model? A model is a kind of data representation that simplifies or generalizes real-world information. As the creator of a GIS, you make decisions on what to include and not include in the data- that in itself is a simplification of the reality on the Earth’s surface.

A GIS can answer all sorts of spatial questions. Here are a few examples.

• Density: As an urban planner, you want to know how many houses are in an area when designing a public transit system.
• Sinuosity: Urban planners design some roads to force drivers to lower their speed by creating winding streets
• Pattern change: Landscapes become fragmented by pockets of residential neighborhoods. What is the impact of this change with respect to wildlife and natural habitat
• Movement: Meteorologists track the paths of hurricanes, and mapping historic tornado data enable the identification of tornado prone zones in the US.
• Adjacency: If you build a summer house, you might be interested in being adjacent to wilderness areas or lake shore proximity
• Proximity: if you are interested in opening a fast food restaurant, you might be interested in the demographic and spending patterns surrounding the location that you are considering. You might also want to determine how many other fast food restaurants are located within a 5 minute drive.

GIS datasets, called layers, are georeferenced and so they can be lined up with one on top of another. All sorts of datasets can be brought together and spatial relationships can be explored and analyzed.

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