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I am working in ArcMap 10.5. I'm trying to identify cliffbands throughout my county, and to assess their approximate height. I've found a source of 1 meter resolution LIDAR data, which I have converted to slope. Many of the cliff bands I've found look like this where the cliff's width spans multiple pixels:

enter image description here

I'm trying to find some way to automate a process where a vector is drawn which follows these cliff bands, then determines the elevation change one or a couple meters to either size, so I can then classify them by cliff height.

I'm still pretty new to GIS so I don't know if this is doable or not.

  • Well, you've got the slope which is a good start but where do you want the cliff to be? At the top, middle or bottom of the slope? You can convert your raster into a binary using Con on the slope and polygonize it then try Collapse Dual Lines help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//… to try to get a centre line but it's not going to be very good based on your image.. better you draw by hand, as for getting the heights you can use zonal statistics (spatial analyst license required) to get the min/max of your polygon and thence determine height. – Michael Stimson May 10 '18 at 3:54
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I have used the technique outlined in this article to identify ridge lines in the past.

ESRI Article - Identifying Ridgelines using a DEM

You need to have access to the Spatial Analyst / 3D Analyst Licenses and Hydrology Tools.

Summarising the article"

  1. Run the Fill tool on your DEM
  2. Multiply the Filled DEM by -1 to invert it
  3. Run the Flow Direction, Flow Accumulation Tools
  4. Use the Raster Calculator to set limits for the Flow Accumulation raster, and define a stream network
  5. Create a stream order and stream feature from the outputs in steps 1 to 5

This should give a decent starting point, from which you can use the Slope layer to filter out definite cliffs.

You can also use the "Add 3D Surface Information" Tool in 3d Analyst to calculate the elevation in mamsl / famsl of the cliff face.

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