Calculating correct slope values after projecting raster issue?

Discussion created by rrmiller on Jan 16, 2012
Latest reply on Jan 19, 2012 by rrmiller

I have been struggling to get spatial analyst to return accurate percent slope values off a set of 1/3 second NED's downloaded off the USGS.  The NED's were downloaded in GRID format.  I brought them in to ArcMap version 10 and projected them into a UTM projection (to convert the units from DD to meters) using the project raster tool.  Then I calculated slope percent (using bilinear interpolation), but for some reason the percent values it returns are really high (highest being 504%).  Has anyone run into this issue? or does anyone have any suggestions for what I might be doing wrong?  Thanks.