About calculating hillshade
This topic was updated for 9.3.1.
How to calculate hillshade
From the ArcGIS Spatial Analyst toolbar, you can create a shaded relief map from an elevation raster using the Hillshade tool.
The default azimuth and altitude values work well for graphical display. For analysis, you may want to modify these values.
Azimuth is the angular direction of the illumination source (for example, the sun); the default angle of 315 is northwest.
Altitude is the slope or angle of the illumination source above the horizon. The default is 45 degrees above the surface.
Learn more about calculating hillshade
Learn how to calculate hillshade using the Hillshade tool
Learn about other Spatial Analyst toolbar functions
- Click the Spatial Analyst dropdown arrow, point to Surface Analysis, and click Hillshade.
- Click the Input surface dropdown arrow and click the surface for which you want to calculate hillshade.
- Specify the azimuth value you want to use. The default is 315 degrees.
- Specify an altitude value. The default is 45 degrees.
- Optionally, check Model shadows. By checking this option, those cells that will be in the shadow of another cell will be identified. Cells that are in the shadow of another cell are coded 0; all other cells are coded with integers from 1 to 255.
By leaving this option unchecked (the default), the local illumination is calculated whether the cell falls in a shadow or not.
- Specify a z-factor if your z units are in a different unit of measure than your x,y units. Z units are multiplied by the z-factor specified to convert the z units to the same unit of measure as the x,y units.
- Optionally, change the default Output cell size.
- Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
- Click OK.
- It is important to specify a z-factor if the z units are not in the same unit of measure as the x,y units. For instance, if your x and y units are in meters and your z units are in feet, you would specify a z-factor of 0.3048, since there are 0.3048 meters in one foot.
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