Spatial Analysis Based on Raster Data Processing - Introducing Geographic Information Systems with ArcGIS - page 511

Exercise 8-5 (Project)
Rasters: Distance and Proximity
Making a Raster Showing Straight-Line Distances to a Single Place
In the following steps, you will see how ArcMap Spatial Analyst makes a raster of Euclidean (straight-line)
distances from each cell to a single “source” cell.
1. Start a new blank map. From Customize > Extensions make sure the Spatial Analyst box is
checked.
2. Click the Add Data button. In the Add Data dialog box, navigate to the shapefile Square_grid
.shp (it's in
___IGIS-Arc_ YourInitials \Spatial_Analyst_Data\Proximity_Data_SA)
and add it to the map. Make the lines of the shapefile bright red. Save the map as Proximity_
startup.mxd, in
___IGIS-Arc_ YourInitials \Spatial_Analyst_Data\Proximity_Data_SA
Note that “Square_Grid” appears as a 10 by 10 matrix of transparent squares. Each square is 10 units
(say the units are kilometers) on a side, so the square represents a space 100 square kilometers.
Square_Grid will serve as a backdrop for the next several raster datasets. You will work in your folder
Spatial_Analyst_Data\Proximity_Data_SA and with the file geodatabase Prox-Exp.gdb (named for Proximity
Experiments).
3. Bring up the ArcCatalog tree. Navigate to
___IGIS-Arc_ YourInitials \Spatial_Analyst_Data\Proximity_Data_SA\Prox-Exp.gdb
file geodatabase, and drag the raster named Onecell onto the map. Onecell is a raster
consisting entirely of No Data values, except for a single cell with a value of 999. Use Identify
to verify this. Open, examine, and close the attribute table for Onecell. In the T/C, change the
color of OneCell to solid black. See Figure 8-46.
4. From the T/C, bring up the Properties of Onecell. Under Source, notice that the cell size is 10
by 10 and there are 10 rows and 10 columns in the raster. Scroll down to look at the rest of the
information, though it's pretty uninteresting, given that the entire raster consists of only one cell
that isn't NoData. Under Symbology, check to see that Unique Values highlighted. Cancel the
Layer Properties window.
By using Spatial Analyst, you will be able to make a raster whose cells contain the distances from the
center of each cell in the raster to the center of the source cell (Onecell).