Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Chapter 8

Spatial Analysis Based on Raster Data Processing

STEP-BY-STEP

____ Open your Fast Facts File.

____ Open the Color Figures file.

Exercise 8-1 (Project)

Basic Raster Principles and Operations

____ 1. Start ArcCatalog. Make a folder named Raster_Experiments in your

___IGIS-Arc_YourInitials

folder. Make a folder connection to that folder. Now make a File Geodatabase named Ras_Expr.gdb inside that folder. Also make sure that the Spatial Analyst extension is turned on (You will also have to turn it on in ArcMap later.)

First, let’s create a tiny, trivial, basic raster to work with. There are several ways to create a raster. We could create a point shapefile, as we did in the project where we mapped the computer terminals, and then convert that to a raster. We will do that in a future project. Another method would be to use the ASCII to Raster tool (in ArcToolbox > Conversion Tools > To Raster). This needs a text file, which we will create. (When I say “we” will use a certain tool you have, of course, noted that I make the suggestions and you do the work.)

____ 2. Using a text processor, make a text file as shown in the lines of characters that follow. Call the text file Forty_Two_Cells.txt and save it in the Raster_Experiments folder.

NCOLS 7

NROWS 6

XLLCENTER 4150

YLLCENTER 1150

CELLSIZE 100

NODATA_VALUE -32768

21 22 21 23 23 23 23

21 25 25 25 25 25 25

21 25 23 23 23 24 24

29 27 25 23 23 26 26

25 27 29 26 27 23 23

27 27 27 21 21 23 23

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