GIS For Dummies®

Chapter 13

Working with Statistical Surfaces

In This Chapter

Knowing what makes surfaces tick

Working with the various types of statistical surfaces

Estimating values with interpolation

When most folks hear the term surface, they think of the physical surface of the ground beneath their feet. Paper maps that show topography use elevation lines, and some globes actually have raised surfaces to indicate mountain ranges. With GIS, surface means much more than the physical topography. You can map and analyze many different statistical surfaces, which include features such as population density, crime rates, and cost of living. This chapter shows you the ins and outs of statistical surfaces, beginning with an overview of just what makes them tick.

Examining the Character of Statistical Surfaces

In GIS, the definition of surface is much broader than simply the physical surface of the land, or topographic surface. Surfaces can relate to other factors of the physical environment that help to create non-physical, or statistical, factors.

Non-topographic statistical surfaces come in two general forms — those relating to the physical environment and those relating to the human environment. This breakdown doesn’t have any intrinsic value; it just provides a simple way to categorize non-topographic statistical surfaces. In the following sections, I refer to only those human environmental factors that relate to social and economic activities because these factors are easier to understand than ...