The model bld_simple_shd.cfg includes examples of
different types of shading obstructions:
a) rectangular blocks for parts of adjacent buildings
   and a tree;
b) general polygons representing the corners of
   adjacent building that are not square;
c) general polygons giving a more realistic tree
   representation;
d) a general polygon representing a gable end; and
e) a rectangular block with 10 degree Y-axis rotation
   to represent a roof overhang.

Note that the model bld_simple_fzy.cfg uses a fuzzy
logic controller which which may cause problems at
simulation time.
