Chief Information Officer: Matthew B. Arvay



 

 

GIS Technology

 

layers of a GIS

What is GIS?

Simply put, a GIS combines layers of information about a place to give you a better understanding of that place. What layers of information you combine depends on your purpose—finding the best location for a new store, finding homeowner information, analyzing environmental damage, viewing similar crimes in a city to detect a pattern, and so on.

Mapping Where Things Are

GIS let's people map where things are and  lets you find places that have the features you are looking for and to see where to take action.

  1. Find a feature—People use maps to see where or what an individual feature is.
  2. Finding patterns—By looking at the distribution of features on the map instead of just an individual feature, you can see patterns emerge.

This map shows the location of man-made objects such as buildings, antennas, and towers, as well as landscape features that can pose dangers to aircraft leaving or approaching airfields.

How to Do GIS Analysis

Frame the Question

Start your GIS analysis by figuring out what information you need. This is most often in the form of a question:

  • Where were most of the burglaries last month?
  • How much forest is in each watershed?
  • Which parcels are within 500 feet of this liquor store?
  • How close a drug arrest was to a school property?
  • How many and what kind of crimes occured in your neighborhood?

Be as specific as possible about the question you want to answer. This will help you decide how to approach the analysis, which method to use, and how to present the results.

  Accoustical impacts of a rocket engine

This map shows the Riverboat at Casino Aztar. The green outlines are property boundaries which contain information like address, lot size, owner name, etc.

Why Use GIS?

  1. Improve organizational integration.
  2. Make better decisions.
  3. Make maps.

Real-world examples: Evansville/Vanderburgh County



 

Improve Organizational Integration

One of the main benefits of GIS is improved management of your organization and resources. A GIS can link data sets together by common locational data, such as addresses, which helps departments and agencies share their data. By creating a shared database, one department can benefit from the work of another—data can be collected once and used many times.

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Make Better Decisions

The old adage "better information leads to better decisions" is true for GIS. A GIS is not just an automated decision making system but a tool to query, analyze, and map data in support of the decision making process.

For example, GIS can be used to help reach a decision about the location of a new housing development that has minimal environmental impact, is located in a low-risk area, and is close to a population center. The information can be presented succinctly and clearly in the form of a map and accompanying report, allowing decision makers to focus on the real issues rather than trying to understand the data. Because GIS products can be produced quickly, multiple scenarios can be evaluated efficiently and effectively.

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Make Maps

For simplicity's sake we often call GIS "mapping software." We most often associate maps with physical geography, but the map to the right demonstrates that GIS is flexible enough to map any kind of terrain, even the human body. GIS can map any data you wish.

Making maps with GIS is much more flexible than traditional manual or automated cartography approaches. A GIS creates maps from data pulled from databases. Existing paper maps can be digitized and translated into the GIS as well.

The GIS-based cartographic database can be both continuous and scale free. Map products can then be created centered on any location, at any scale, and showing selected information symbolized effectively to highlight specific characteristics. A map can be created anytime to any scale for anyone, as long as you have the data.

This is important because often we say "I see" to mean "I understand." Pattern recognition is something human beings excel at. There is a vast difference between seeing data in a table of rows and columns and seeing it presented in the form of a map. The difference is not simply aesthetic, it is conceptual—it turns out that the way you see your data has a profound effect on the connections you make and the conclusions you draw from it. GIS gives you the layout and drawing tools that help present facts with clear, compelling documents.

Source: GIS.com and Evansville GIS Department

Copyright ©2003-2006 Evansville GIS Department