You’ll start your analysis project by using the Spatial Analyst toolbar. You’ll run the Hillshade tool so you can view and explore the output from this tool with the rest of your input data later in this example. A hillshade is a shaded relief raster created by taking an elevation raster and setting an illumination source (for example, the sun) at a user-specified azimuth (the angular direction of the illumination source, in positive degrees from 0 to 360) and altitude (the angle of the illumination source above the horizon). The visual effect of a hillshade can be dramatic when it is displayed under other transparent layers in your ArcMap display.

If your x-, y- and z-values are all in the same unit of measure (for example, if they are all in meters), you can accept the default x-factor of 1, so the z units are not converted. The x,y units in the elevation data, however, are in meters, and the z-values (the elevation values) are in feet. By multiplying the z-values by a z-factor of 0.3048, they will be converted to meters, since there are 0.3048 meters in one foot.

Note: Setting an appropriate z-factor is critical for good results if your input surface is stored in a geographic coordinate system (for example, the x,y units are a spherical measurement, such as decimal degrees or decimal seconds). Type “Hillshade tool/command” into the index of the ArcGIS Desktop Help system for an explanation of suitable z-factors. The z-factor can also be used for exaggeration of the terrain.

The cell size (value of 30 meters) of the input dataset will be used for the output cell size, since environment settings have not been specified on the Options dialog box (accessed via the Spatial Analyst toolbar context menu).

In this example, instead of creating a temporary raster output, you'll see how to create a new, permanent raster in your Results folder.