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

Using Cost Distance to Make Direction and Allocation Rasters

Solve the following problem in a new map. Basically, you are repeating the previous exercise, but using cost distance instead of Euclidean distance. The distances are calculated differently. In the Euclidean case they are straight line distances; using cost distance the distances are calculated along a path which goes from cell center to cell center.

____ 30. Open Proximity_startup.mxd. Add TryThis as a source raster and Tolls as a cost raster. Make the color ramp of Tolls “Purple Bright” treating its T/C labeling as you when you added it last time.

____ 31. Find and start the Cost Allocation tool. TryThis is the Input raster. Value should be in the Source field. Tolls is the Input cost raster. Browse to Prox_Exp.gdb and name the Output allocation raster CostAllo. Make the Maximum distance 30. Call Output Distance raster CostDist. Call the Output backlink raster CostDir. Double-check that you are using Prox_Exp.gdb for all output rasters. Click OK.

____ 32. The new rasters should appear in the T/C. Collapse the legends in the T/C. Click on List By Drawing Order, and arrange the entries in the T/C in the following order: Square_Grid, TryThis, CostAllo, CostDir, CostDist, Tolls. Turn off all except Square_Grid and TryThis. Examine TryThis with Identify, and the T/C (which you may have to re-expand), so you know what is where.

____ 33. Start the Identify tool and set it so that it shows the values of CostDist, even ...