Tips for Building Classification

When running the Classify Building routine, for best results one should typically keep in mind the following:

  • The building routine should be run on elevation stratified point classes.
    • May be best to classify all points for one type of buildings into a single vegetation class, such as medium vegetation
    • The class should straddle just below the lowest roof points to just above the highest roof points
  • The accept using rules controls the points to be classified. The looser the rules the more points to be classified corresponding to the found plane.
  • Z tolerance controls the fit of a plane. Make this tighter to minimize false positives in vegetation. The Z tolerance should be on par with the noise level of expected hard surface returns.
  • Should always use echoes if available.
  • Points at the edge of planes, such as the intersection of two roof planes generally will not get classified. You can use the Classify by CloseBy Points to add additional points to the building class.
  • The minimum building size needs to be large enough to cover at least four points otherwise the routine may run for an extremely long time as it attempts to fit planes to everything.
  • The minimum building size should be set to slightly smaller then the square area of the smallest building you wish to classify.
    • This is a building setting, irrespective of the number of planes in a building roof.
    • The larger the size the less likely to find false positives in the vegetation.

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