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We will assume that the stereo rig is calibrated, that is the PPMs are known. This assumption is not strictly necessary [5, 8], but leads to a simpler technique. The idea behind rectification [2] is to define two new perspective matrices which preserve the optical centres but with image planes parallel to the baseline. In addition we want the epipolar line of the point tex2html_wrap_inline1217 in the right image to be the horizontal line tex2html_wrap_inline1219 in the left image.

Consider Fig. 4 where the old retinal plane tex2html_wrap_inline1221 and the new one tex2html_wrap_inline1223 are depicted: image rectification is the operation of transforming from tex2html_wrap_inline1221 to tex2html_wrap_inline1223 .

Figure 4: Rectification.

Andrea Fusiello
Tue Feb 3 17:18:41 MET 1998