Chapter 17

Map Algebra and Model Building

In This Chapter

Using cartographic modeling

Getting the hang of map algebra

Understanding the map algebra language and functions

Creating a model

Going live with your model

Testing to make sure that your model makes sense

If you started reading this book here, you’re anxious to get started making the GIS work for you. Although retrieving maps and doing all the individual analyses are often enough for everyday tasks, every now and then, you want to watch the GIS spread its wings and do something really spectacular. This chapter explains how you can let your GIS really soar.

realworld(gis).eps The original ideas and concepts underpinning this chapter are the brainchildren of Dr. C. Dana Tomlin and his PhD advisor, Dr. Joseph K. Berry, then at the Yale School of Forestry. Their work has had a lasting and substantial impact on how you can use GIS to make models with maps.

In this chapter, I use the raster model to demonstrate how cartographic modeling works. I also show you the basics of the cartographic modeling language called map algebra, the functions that the language provides, and how map algebra creates powerful models. Finally, I show you how you can test the output from map analysis for accuracy and acceptability.

Creating Cartographic Models

When C. Dana Tomlin developed his original Map Analysis Package (MAP) for his dissertation, he wasn’t thinking ...

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