topic Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc? in Elevation Data Questions

Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc?

SarahPeirce — Wed, 28 Mar 2018 17:08:08 GMT

I have a DEM with a known overall slope of 1.5% which I would like to remove for visualization purposes (image of non-detrended DEM attached).

Any help would be greatly appreciated.

Re: Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc?

AbdullahAnter — Wed, 28 Mar 2018 20:54:51 GMT

I don't understand what exactly you want to do, because The title differs from the image in context.

Anyway , (as your title )i see the following tools maybe help you:

Con—Help | ArcGIS Desktop

Extract by Attributes—Help | ArcGIS Desktop

Re: Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc?

DanPatterson_Retired — Wed, 28 Mar 2018 21:14:30 GMT

If there is indeed a trend, did you try to run a first order (linear) trend surface on the data and subtract the resultant from the input dem?

http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/trend.htm

http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/how-trend-works.htm

Not sure if the tool exists in the same locale (or if at all) in PRO.

Worth a first run... otherwise you could generate the surface I suppose from first principles (ie using numpy meshgrid and generate the z values from a 2D equation, then convert back to raster for subtraction

Re: Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc?

DanPatterson_Retired — Sun, 12 Dec 2021 09:11:25 GMT

I have messed a bit with artificial terrain generation

https://community.esri.com/blogs/dan_patterson/2017/12/28/terrain-creation-diamond-square-algorithm

But I haven't played with input parameters to generate exact slopes and aspect terrain... but this might give you some idea. See the link.

# ---- A 'slope' with a NW aspect ----
array...
[[ 0.250  0.351  0.420  0.488  0.542  0.604  0.656  0.704  0.750]
 [ 0.342  0.383  0.443  0.502  0.559  0.613  0.663  0.706  0.732]
 [ 0.392  0.427  0.469  0.525  0.578  0.630  0.677  0.714  0.740]
 [ 0.438  0.463  0.503  0.551  0.601  0.650  0.694  0.732  0.754]
 [ 0.458  0.493  0.531  0.577  0.625  0.673  0.719  0.757  0.792]
 [ 0.496  0.518  0.556  0.600  0.649  0.699  0.747  0.787  0.812]
 [ 0.510  0.536  0.573  0.620  0.672  0.725  0.781  0.823  0.858]
 [ 0.518  0.544  0.587  0.637  0.691  0.748  0.807  0.867  0.908]
 [ 0.500  0.546  0.594  0.646  0.708  0.762  0.830  0.899  1.000]]‍‍‍‍‍‍‍‍‍‍‍

Hope you get the idea, but you would have to mess with the corner values for your raster extent and put in values to reflect the slope's orientation and not only its slope

There are other algorithms out there

Re: Is there a way to remove a known slope from a DEM (i.e., detrend a known slope) in Arc?

SarahPeirce — Tue, 26 Jun 2018 20:13:45 GMT

Thank you for your help!