What is GIS?
23 Mar 2010 Jason 0
GIS, which stands for Geographic Information System, is a huge topic, difficult to restrict to a simple or concise definition. It covers everything from a simple GPS handheld device that gives you your current location to tracking the growth of the Gobi desert. It is the science of translating geographical information into a format that can used to make informed decisions on anything from where to locate a new supermarket to finding the nearest gas station and everything in between.
The one thing that binds all these different things together is that they are related to geography, or location. Both spatial and non-spatial data (see the box Spatial vs Non-spatial) can be stored for analysis purposes to help us make sense of the world around us.
A GIS is made up of several parts including:
- Personnel – Staff trained in collecting and processing GIS data.
- Data – Data collected for the purpose of building a GIS system. Most of the work in creating a GIS is in collecting accurate data.
- Software – Software applications designed to help with the collection, recording, storage and retrieval. A popular GIS software application is GeoBase, which allows companies to develop customized mapping solutions.
- Hardware – This can include dedicated web servers for running web-based GIS applications (such as Google Maps) to handheld GIS data collection devices.
Spatial vs Non-spatial You might hear the terms spatial and non-spatial used when talking about GIS data. It sounds complicated but it can easily be explained if we understand what the word spatial means. Essentially it is anything related to, or having the nature of, space. The space we’re referring to is not the final frontier space tackled by the USS Enterprise but instead object data that includes location, shape, size, and orientation. For example, the center of a square (where the diagonals intersect) specifies the object’s location and is thus spatial data.
Non-spatial data (also referred to as attribute or characteristic data) is data which is independent of the spatial features such as location or size. Using the example above of a square, it might be a red square. This is non-spatial data since it is red regardless of its size, shape, location or orientation.
Both spatial and non-spatial data can be included in GIS overlays.
There are many different uses of a GIS and they are used by businesses, government departments, non-profit groups and even individuals to interpret and analyze geographical information.
Here’s an example to illustrate, in a basic way, how you might use a GIS. Say you wanted to setup an ice cream parlor in L.A. but you weren’t sure of the best location. Knowing that most of your customers will be young children with a sweet tooth, you use a mapping tool to show a map of the city overlaid with age data of the people living in different areas, using publicly available census information.
You can see from the illustration above that, as you would expect, there is a younger population close to available schools. If the GIS included attribute information on the type of school, you might be able to narrow it down to elementary schools targeting the children under 12. Based on this information, you choose a location for your ice cream parlor where there is the heaviest density of young people under 12, thus increasing your likelihood of making more sales. You’ve also just used a GIS to solve a real-world information need.
Vector vs Raster GIS data GIS data (also known as geodatabases) is normally represented in two main ways – vector or raster. The type of information will generally determine whether vector or raster is used.
Maps using static images to display features of the earth’s surface, such as vegetation type or census information, are more likely to be displayed using raster (e.g. a map filled with colored points, or cells, to highlight different zones or themes) whereas vector (made up of polygons, lines and points) can provide a more simplified view of an area, showing city locations, roads, lakes and other non-adjacent locations on a map.
The great thing about a GIS is that they can be custom built to suit the individual’s needs, so there’s no limit to how it can be used in the real world. Its uses are as varied as the different companies, groups or individuals that use it. Anything from environmental analysis to crime mapping, urban planning and transport logistics can all use a GIS to solve real-world problems.
While GIS has no special problem-solving properties in itself, it provides a very helpful platform to empower decision-makers to more accurately analyze the real-world, and hopefully make better choices.
As mentioned at the outset of this article, it is very difficult to offer a definitive, all encompassing explanation of what GIS is, so hopefully this has at least given you a broad overview that goes someway to explaining the term. To help explain it further, we’ll consider a real-life use of a GIS in our next post.