Bitelli, Gabrielle 
delimit planes with different depths, shadow zone limits and rounded geometric features. The number of points to be 
acquired depends on the complexity of the surface to be described. An undulating surface requires the insertion of 
adjacent profiles or sections with a sampling step directly dependent on its curvature. In the presence of surfaces with 
different depths, simply delimit the edges, bearing in mind that, with triangulation, each of the polylines plotted will 
become the side of a triangle which is, as far as possible, equilateral, forming an object surface consisting of triangles, 
  
  
  
- à - “bp 
Figure 5 - Orthophoto of a portion of the Zabbar Gate façade; a) with DSM generated automatically, without a 
posteriori editing (spot pixel 9; A); with DSM generated by interpolation of the analytical plotting (B); b) Detail of the 
colonnade and original DSM with regular mesh (A) and with triangular mesh (B). 
A visual comparison of the result obtained by a traditional architectural plotting product versus the adoption of 
orthophoto can be obtained by figure 6, where the right side shows the orthophoto previously described in figure 5aB 
with superimposed the main features. 
Y (mm) 
  
X (mm) 
Figure 6 — An example of traditional vector plotting in comparison with othophoto for the facade. 
  
68 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
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