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Shaded relief in low relief areas

May 24 2011 | 0 comments
Categories: Symbology

I keep running into issues when trying to generate shaded relief maps in low relief areas. Areas that are essentially flat, which should be illuminated consistently, end up with very odd blotchy ?aliasing? patterns (see attached example). I have not had any luck finding a solution to this problem from within ArcMap.

Do you have advice for me regarding solutions to the problem? How can I get planes to show up as planes and not a bunch of small-scale hills?

Thanks!

Mapping Center Answer:

This looks to me like you are creating the hillshade from data in a geographic coordinate system, which has no linear units and thus the elevation values are assumed to be in decimal degrees. There are two solutions: 1) project your data into a projected coordinate system, then the linear units will be in either meters or feet, or 2) use the Z factor to add a conversion factor to allow the elevation units to be interpreted correctly.  Here is a blog entry we wrote about how to set the Z factor if you take the second approach.

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