Main Functions

  • Fill null: the first value is assigned, i.e. the value with the highest priority (if it is not null) is used;
  • Add: If the pixel has already been assigned, the value of the current layer (if it is not null) is added to the previous one, otherwise the value is assigned to the pixel. It is useful to compose basic topography and buildings topography, when only heights are available, but not absolute elevation;
  • Subtract: If the pixel has already been set, the value of the current state is subtracted from the previous one (if it is not null); otherwise the sign of such value is changed and the resulting value is assigned to the pixel. It is useful to assess differences among different DEMs;
  • Differences: If the pixel has already been set and the value of the current state is different, the difference will be assigned to the same pixel. It is useful to assess differences among different DEMs.