How to rasterize walls for grid calculations

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 two conditions: (1) the smoothed DSM exceeds the DTM by at least 1 meter, and (2) the smoothed DSM exceeds the local raw DSM by at least 1 meter. Both must be true for a cell to be classified as a wall. By changing the "1" into a lower or higher number, the approximation can be made more or less sensitive respectively.

API Endpoints

• Api session event editor overlay add
• Api session event editor overlay set avg distance
• Api session event editor overlay set prequel
• Api session event editor overlay set combo formula