Chapter 4

Creating a Conceptual Model

In This Chapter

Compensating for your computer’s lack of map-reading skills

Understanding how to select the right maps for your GIS

Figuring out what you want in your maps

Inputting map data into your computer

Maps are complex devices that hold tons of information. Some of that information appears outright in the symbols, but a map imparts much information more subtly, almost covertly. A single shading pattern that represents the distribution of a soil type explicitly shows where the soil is located. But such shading patterns also tell you what soils are adjacent to other types of soils, the relative amounts of each soil type, and even how often the types occur in a single piece of land.

For another example, if your map has point symbols that represent the locations of churches, each point symbol links explicitly to a church’s absolute map coordinates. And when you look at a church symbol on an area map, you can also see a measurable distance to other churches and to potential churchgoers, how many churches are in the area, and their locations within the area’s topography. If you’re looking for the Church on the Hill, you can probably find it on a hill.

Maps are complex, and human map readers (like you) interpret much of the information that those maps contain. So, to create a GIS that has both complex and useful information, you have to show the computer how to think like you do as a map reader.

Formulate a conceptual model (a picture in ...

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