The Aspect (Spatial Analyst or 3D Analyst) tool calculates the direction in which slopes are facing. Values are given in degrees in regards to the degrees on a compass (with north as 0 and 360 degrees).

To calculate the aspect of the terrain (Fig. 43):

  1. Type “aspect” into the Search window (or browse to Spatial Analyst Tools > Surface > Aspect in the ArcToolbox).
  2. Select the Aspect (Spatial Analyst or 3D Analyst) tool.
  3. Choose the DEM as the input raster.
  4. Save the output raster as aspect.
  5. Click OK.

In the TOC the results (Fig. 44) can be seen in degrees.

Fig. 43. The Aspect tool dialog box.


Fig. 44. The result of the Aspect calculation from the DEM.