Ask A Cartographer


February 08 2010 | 0 comments
Categories: ArcGIS Methods, Map Data

I am doing a report on GIS and I had to explain the difference in heights between the original DEM, hillshade DEM, tin and interpolate. I noticed that the minimum height of my hillshade was 0 when the rest of the tools was -3, why is the hillshade tool starting at 0??

Mapping Center Answer:

The values in the DEM relate to elevation, usually in meters or feet. The values in the hillshade relate to the about of illumination that the surface receives, and the values range from 0 (no illumination - i.e., full shadow) to 255 (full illumination -- i.e., full sunlight). Tin facets are slightly differnt since theya re not in grid format.  Here is some additional reading you can do to learn more:

Exploring Digital Elevation Models

How Hillshade works

How TIN to Raster works

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