~F85. COMPARING.

	Third,  all  the unmated polygons  of a level  are considered
two  at a time and  a fusion shape node  for each pair is  made.  The
potentially (N*N/2-N) fusion  shapes are avoided  because there is  a
maximum possible  unmated inertia  in the other  image; lo,  if there
are  no unmated polygons in one image  then the extra polygons of the
first image  can be  ignored. In the  event where  there are  unmated
polygons  in  corresponding levels  of  the  two  images, the  fusion
shapes of one  are compared  with the  polygon shapes  of the  other.
The  fusion  (fission)  compare  solves  the  rather  nasty  problem,
illustrated in  figures 9A and 9B of  linking two contour polygons of
one image with a single contour polygon in the next image.

	Fourth, the vertices of  polygons mated in time are  compared
and mated.  To start a  vertex compare,  the vertices of  one polygon
are  translated,   rotated and dilated  to get  that polygon's lamina
inertia tensor  coincidant with  its mate  (or mates).  Conceptually,
each vertex of one polygon  is compared with each vertex of the other
polygon(s)  and  the  mutually  closest  vertices  (closer  than   an
epsilon) are  considered to  be mated.  Actually the potential  (N*M)
compares  is avoided by  a window  splitting scheme similiar  to that
used in hidden line elimination algorithms (like Warnock's).

	The results  of vertex compare  and mate  are illustrated  in
figures 9A and 9D; the compare  execution takes less than a second on
images  such as the  pump,  blocks,  and dolls that  have appeared in
this  paper. The  applications  of  this compare  might  include  the
aiming   of  a  pixel   correlation  comparator  (such   as  Quam's);
recognition and location of an  expected object; or the location  and
extent of  an unknown  object.   It is  this latter application  that
will be described in my forthcoming thesis.
~I1973,800;F8- 33 -