Changing the illumination angle of a hillshade

You may want to change the illumination angle when applying a shaded relief or hillshade to a digital elevation model (DEM). There are three locations within the ArcMap window where the illumination properties can be altered:

• On the Data Frame Properties dialog box
• On the Image Analysis window's Processing Options dialog box
• From the Layer Properties dialog box

1. To change the illumination properties for a data frame, do the following:
   1. Right-click the data frame containing the DEM layer and click Data Frame Properties.
   2. Click the Illumination tab.
   3. Adjust the azimuth angle.
   4. Adjust the altitude angle.
   5. Optionally, you can adjust the contrast of the hillshading.
   6. Click Apply to see the changes.
   7. Click OK to close the Data Frame Properties dialog box.
2. To change the illumination properties that are applied when creating a hillshaded or shaded relief layer using the Image Analysis window, do the following:
   1. Click the Image Analysis Options button on the Image Analysis window.
   2. Click the Hillshade tab and adjust the illumination properties.
   3. Click OK to close the Processing Options dialog box.

   Note:

   The illumination properties must be set before you click the Shaded Relief button; otherwise, you need to follow the steps below.

3. To change the illumination properties for a hillshaded or shaded relief layer created from the Image Analysis window, do the following:
   1. Create your hillshaded raster layer using the Shaded Relief button.
   2. Right-click the raster layer in the table of contents and click Properties.
   3. Click the Functions tab.

      Functions are added within a mosaic dataset and by the temporary raster layers created from the Image Analysis window. They are used to define processing, which is applied on the fly.

   4. Right-click Shaded Relief Function and click Properties.
   5. Click the Shaded Relief tab and edit the properties.
   6. Click OK to close the Raster Properties Function dialog box and click OK again to close the Layer Properties dialog box.

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