Let's take a little tour of the basics of GIS with everyone's favorite green superhero, Norman, and our dear friend, Professor John.

To begin with, what is GIS exactly?

-- Geographic: real world; spatial realities 

-- Information: data and their meaning 

-- Systems: computer technology

Information is the heart of GIS and allows the user to analyze a variety of different sets of geospatial data in a computerized format.

Okay, that clears things up a bit…but what does GIS actually involve?

-- First, you have to collect the information (either through aerial photographs, surveying information, paper maps, manual measurements, remote sensing). 

Next, the information is stored or inputted into a computer system. This creates a database of geographic information. This is the output. 

-- The database is then managed and organized into different folders for easy access. 

-- Then, people like me, retrieve that information on their computer (yes, I know, that makes me a bit of a computer nerd, but that's the life of some geographers). 

-- After I have retrieved the data, then I can analyze the different information contained in the database and create all sorts of different kinds of models. 

-- Once I have that done, then I can display my final product either via the computer or in detailed paper maps which I can print out using the program.

So you're telling me, you can look at all of this stuff on the computer? What exactly does it look like?

Well I'm glad you asked that…there are two basic ways that the data is represented on the computer screen in a GIS program.

-- First is what we call a Vector format. The Vector format utilizes X and Y coordinates like on a big graph. The computer recognizes points (like cities), lines (like roads), and polygons (like forested areas). 

-- The second type of format is what we call Raster. In the Raster format, cells or pixels are used on the computer screen. Each cell is then assigned a specific identity (a city, road, or forest for example).

Okay, hold on Doc! How could you possibly look at it on the computer screen without going crazy?

It's actually quite simple. A company named Environmental Systems Research Institute makes a great software package called Arcview. This software allows you to view and organize your data very easily. 

-- Arcview is organized like this:

*View window (allows you to look at spatial data; the map itself) 

*Table window (allows you to look at data in a spreadsheet form) 

*Charts/Graphs (creates visual representations of what you are looking at) 

*Layout (allows for creation of really cool map products) 

*Script (computer language used to customize the program)

WOW! That still sounds like an awful lot of stuff. All I would probably look at is the maps with all the pretty colors!

In truth, 90% of my time is spent looking at the View and Table windows. 

 

-- In the View window, you can do some amazing things:

*You look at the data in layers or themes.

>Some example themes include; land use, streams, flood prone areas, elevation, topographic maps, land cover, sewer systems, etc. 

>You can overlay (or stack together) different layers/themes to create really dynamic maps. 

*There are some very useful things you can do with these different layers.

> Location and Identity of specific points, places, etc.

  >Spatial measurements (distance, perimeter, area)

  >Create trends and models.

  >Create buffers around streams and wetland areas.

  >Clip and merge different themes together.

  >Map calculations. 

 

--In the Table window you can also do some cool things.

*This window allows you to view alphanumeric data. For example; city name, county, state, area in square miles, distance, acreage, perimeter, population. 

*You can also perform a Query:

>This allows you to question the computer to get a specific set of data from the database you are looking at. 

>For example, if you were looking at the parcels of Tewksbury Township, you could determine how many of the parcels are 200 acres or larger. 

>The neat thing about querying is that you can also do it in the View window and it will highlight the parts of the map that match the answer to your query!
 

 
 

 

SPOON! I think I actually get it! What an amazing thing! You mean I can look at whatever kind of information I want to and it will come out on a map?

Yes, my big, blue friend, as long as the data is in the computer, you can look at the information you need to look at! It's a great system and will help with a great many things, like Environmental Planning, in the future! I hope our little tutor session has helped!

Oh joy, oh joy! I can use it to track where crime is occurring throughout the city. Then I will be the most well prepared superhero in history! Thank you so much Professor John!

Go to Description of the Procedure for our Project

Go Home