User manual

Small Vision System User Manual 21
2.4.4 Disparity Search Range
Even with stereo rectification, it may not be possible to match every object in the scene, because the
horopter is not large enough. In this case, the horopter can be enlarged by changing the number of
disparities searched by the stereo process. This search range can vary from 8 to 80 pixels. Larger search
ranges enlarge the horopter, but not in a linear fashion, i.e., a search range of 32 does not give twice the
horopter range of 16; see Section 4 for technical details.
Changing the disparity search size affects the time it takes to process stereo. A search space of 32
pixels will take about twice as long as a search space of 16 pixels. It will actually take a little less,
Figure 2-7 Original stereo pair (top) and rectified pair (bottom).
Figure 2-8 Uncalibrated (left) and calibrated (right) disparity images.