0

I have a large DEM of England that I have clipped to my study area and have been trying to generate a hillshade from. I tried a few variations with the parameters in altitude and azimuth (leaving z =1), but I continue to get this really grainy result using ArcGIS Pro.

enter image description here

The cell size is 0.00027777 decimal degrees. and I tried to re-sample to 1 but got an error that the size was too large. I tried running calculate statistics and building the pyramids on the original DEM but the result hasn't changed any.

5

You are probably generating your hillshade from a surface model that is referencing a geographic coordinate reference system like WGS84. Re-project your data into a Cartesian coordinate reference system (like UTM) and then recreate your hillshade.

1

You left z-factor = 1.

The ArcGIS Pro Help for Hillshade specifically states:

If the input raster is in a spherical coordinate system, such as decimal degrees, the resulting hillshade may look peculiar. This is due to the difference in measure between the horizontal ground units and the elevation z units. Since the length of a degree of longitude changes with latitude, you will need to specify an appropriate z-factor for that latitude. If your x,y units are decimal degrees and your z units are meters, some appropriate z-factors for particular latitudes are:

Latitude     Z-factor
 0           0.00000898
10           0.00000912
20           0.00000956
30           0.00001036
40           0.00001171
50           0.00001395
60           0.00001792
70           0.00002619
80           0.00005156

So pick or calculate a z-factor close the central latitude. Or just reproject to a CRS that uses metres as the horizontal units.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.