Spatial Analysis Based on Raster Data Processing - Introducing Geographic Information Systems with ArcGIS - page 454

background in the basics of GIS, and since this is the only chapter that is devoted to raster processing, the
descriptions of the basics of raster processing will be succinct.

The major package in ArcGIS that processes rasters is called Spatial Analyst. 2 ArcToolbox's Spatial
Analyst Tools have about 20 toolsets with a total of many more than 100 tools. Included as Toolboxes are
the following:

❏ Conditional ❏ Math

❏ Density ❏ Multivariate

❏ Distance ❏ Neighborhood

❏ Extraction ❏ Overlay

❏ Generalization ❏ Raster Creation

❏ Groundwater ❏ Reclass

❏ Hydrology ❏ Solar Radiation

❏ Interpolation ❏ Surface

❏ Surface Analysis ❏ Zonal

❏ Map Algebra

In the Map Algebra 3 toolbox is a Raster Calculator which lets you calculate new rasters, making use of
hundreds of functions, commands, and operators that are part of the Esri Spatial Analyst software.

Within these toolboxes are a large number of tools. It is true that there is considerable overlap in these
software tools. They represent an evolution of raster processing techniques developed over decades. But
even considering these overlaps, one cannot deny the conclusion: Spatial Analyst is big !

You will use Spatial Analyst get a good look at the software as you solve problems dealing with
proximity, cost of moving across an area, siting a picnic park, doing hydrological and watershed analysis,
and make surfaces. Also you will solve the Wildcat Boat problem using Spatial analyst.

Facts about Rasters

Each raster data set must have a name, just as a shapefile or geodatabase feature class must.

Rasters can be, and should be, lodged in a geodatabase. A raster data set may have multiple bands. If so,
Spatial Analyst operates on band 1.

Rasters can be either geographic data or image data. We mostly discussed the structure of image data in
Chapter 4. Here we will concentrate on geographic data.

2 The package that dealt with raster processing in ArcInfo versions before ArcGIS was called GRID. Most
GRID commands have been superseded by Spatial Analyst commands.
3 The idea of “Map Algebra” was developed by Dana Tomlin and presented, in 1990, in a book entitled Geographic
Information Systems and Cartographic Modeling.