When the shapes of
the buildings are irregular, such as the input image in the
third row, the algorithm is incapable of detecting these
buildings.
The algorithm of reference [11] combines the
local color feature and the shape feature simultaneously
to recognize buildings.
In some cases, however, roads and
buildings resemble in both color and shape.
Without the
prior knowledge like shadows, it is impossible to
distinguish a building from its neighboring distracters
with the same color and shape, so that the algorithm tends
to recognize roads and squares as buildings.