Global Mapper Pro

Intersection of two elevation grids

Carl_M Global Mapper User
edited July 2013 in Elevation Data
Hi Mike,

I have tried searching for this query but havent had any luck finding a response. Is there any way to find the intersection between two elevation grids and create a line along the intersection?

Thanks in advance



  • global_mapper
    global_mapper Administrator
    edited July 2013

    You could run an Analysis menu command to create a new grid that is the difference of the 2 layers. This will only create valid samples where both layers are valid. Then just right-click on the new layer in the Control Center and select to create bounding boxes/coverage and select No to get a coverage polygon covering the valid area, which will be the intersection of the 2 layers.


    Global Mapper Guru
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • Personally my workaround is to do as Mike suggests and run a subtraction between the two terrains, then generate a contour at -0.01m (minus 0.01m) on the resultant Combined Elevation Grid. This generates the boundary for the intersection between the surfaces.

    The BBOX/COVERAGES method doesn't work for me but that may be due to the surfaces I typically work with e.g. I create dams across valleys by projecting the dam model through the terrain and then use the boundary to crop the model via the Cropping Tab of the layer.
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