How to rasterize walls for grid calculations

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To identify structure walls for certain calculations, specific localized checks on elevation models are required. By analyzing the behavior and local changes in these models, a spatial calculation can be created to locate these walls.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar)
How to rasterize walls for grid calculations:
  1. Add a Heightmap Overlay, configured as DTM, to the Project (if it does not exist yet)
  2. Add a Heightmap Overlay, configured as DSM, to the Project (if it does not exist yet)
  3. Add an Average Overlay to the Project with the following configuration
    Name: DSM Smoothing
    Set the averaging to the DSM Heightmap Overlay.
    Set the averaging distance to approximately 2.5 times the grid cell size.
  4. Add a Combo Overlay to the Project with the following configuration:
    Name: Walls
    Input A: DTM Overlay
    Input B:DSM Overlay
    Input C:"DSM Smoothing" Overlay
    Formula: AND(GT(SUB(C, A), 1), GT(SUB(C, B), 1))
  5. Modify the legend of the Combo Overlay to have only the following values:
    Value 0: No wall
    Value 1: Wall

Notes

  • This calculation performs an estimation of wall locations and may miss some areas. Therefore, it should not be taken as an absolute value, but can be used as a valid estimation in other calculations, such as the percentage of walls which also overlaps with specific sight-lines.
  • The formula of the Combo Overlay checks whether the localized average DSM exceeds the absolute height by at least 1 meter, which generally means that the height of a wall should be at least 2 meters high. By changing the "1" into a lower or higher number, the approximation can be made more or less sensitive respectively.

API Endpoints

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