LEFT IMAGE RIGHT IMAGE
with ST',ST" ... starting wrong match point locations
AAT... intermediate match point locations (possible side maximum)
Ce. correct match point locations
e nhe Din _ DR (18)
TYL DY, , TYR DYg
FIGURE 4. Movement of match points along "relief" lines
This step ratio can be considered constant for a specific image location, since the Z-derivatives
are practically constant throughout the iterations as we explained before. That means that if the
left patch moves with step S, at a point A”, then the right patch must move with step Sp 2 S, /R
at point A". Thus, a side-maximum can be selected only if it falls at one of the "fixed step ratio"
point pairs (e.g. A'- A’ ) of the relief lines. This means that the probability of hitting a
side-maximum is even smaller than in the epipolar correlation case, since the transfomations of
the patches are not only along lines but they must additionally satisfy the "step conditions".
4.9 CPU Time
Average CPU time per point is listed in Tables 1 and 2. On the average 1 sec per iteration is
needed for 152 patches on a VAX 11/750. The main portion of the time required in each iteration
is for the formation of the normal matrix and secondly for resampling the gray values. Image
processing modules and array processors can considerably speed up the computations,
especially since most of them are of simple algorithmic structure.
5. CONCLUSIONS
The above mentioned results can be summarized as follows:
* The geometric constraints should be treated as stochastic variables with large weight. Their
use increases the reliability of the match (probability of side-maxima is strongly reduced).
- 295 =