nearly perpendicular lines. Figure 3 illustrates such an 
example. Another usual problematic case is that of 
multiple solutions. With geometric constraints side 
minima can only result if they fall along the epipolar line. 
Figure 4 shows an example with and without geometric 
constraints. 
An extension of our approach, which has not been 
implemented yet, is the application of such constraints 
tewplate 
spot2.1roi 
  
  
Sessa? 
Figure 2 Matching without (left) and with (right) constraints. 10 iterations without and 5 iterations with 
for the 4 corners of the patch of the template image. This 
patch represents a part of the object surface which can be 
modelled by different surfaces (e.g. horizontal plane, 
inclined plane, 2nd degree surface). Depending on the 
type of the surface, the heights of the 4 corner points can 
be defined analytically. For example, if an inclined plane 
is selected, the heights at the 4 corner points are a 
function of the height at the patch centre and the two 
template patch. 1 
spot2.1roi spot1.1roi 
   
constraints were needed. The “epipolar line” is the white line in the right image. The black frame 
is the initial position and the white frame with the black centre cross the final position. 
template patch_1 
spot2.1 
    
  
template patch_1 
spot2.1roi spoti.froi 
S , care 
    
Figure3 Matching along edges without (left) and with (right) constraints. 
template patch. 1 
8pot2.1roi spoti.lroi 
  
  
template patch_1 
gpot2.1roi spoti.lroi 
    
  
Figure 4 Multiple solution matching without (left) and with (right) constraints. 
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