Once the shadow area has been determined the grid points designated as 'shadow' are

simply summed together.

 The technique used to determine the shadow areas is borrowed from the line-of-sight

method discussed earlier. A robot is placed at a specified grid point and the remaining

grid points are checked to see if line-of-sight exists. If line-of-sight does not exist the

grid point is in a shadow region. Once again, a matrix is developed that contains all of

the shadow points for each robot.

 The overall shadow area can be determined by combining the data for each robot into

a single matrix. This is done using the Boolean logic operator 'AND' on the matrices.

This results in a single matrix that contains the shadow area information for a specific

map and robot configuration. This method has been applied to a two-robot system in a

20x20 grid (see figure 2.7). More results are presented in Chapter 5.

 Shadow Areas



 ***co
 OO0000 0000000J00
 I0 0 000 0000 0 0 O O O

 0@ 00 0000000000
 0 0 O O O00 0000

 0000000 0 000000000
 0000000 0 *0 0000000
 00000oo0 0o00000000000o
 00000000000000000000
 00000000000000000000
 00000000000000000000







 Figure 2.7: Resulting shadow areas for a simple two robot system (20x20 grid)
 0000C000000000000000
 OOOOOOCOOOoOOOOOOOOO
 0000000000000000000


 Figure 2.7: Resulting shadow areas for a simple two robot system (20x20 grid)

 This method was applied to a single robot on a 50x50 grid in order to visualize where

the maximum shadow areas occur. The robot was placed at every point in the matrix and