17.8. Draw Visibility Map

          This command allows one to identify the areas of a surface which are visible from a specific point. Firstly, the program requests a point from which to perform the process, along with the observer’s height. Then a dialog box is displayed allowing one to configure the layer and the colors to be used.
          By clicking on the colored rectangles, one can change the color that will be used for the triangles that the observer can see and cannot see.