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Topic: Motion matrices in homogeneous coordinates (need help)
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pfe GIMENEZ

Posts: 1
Registered: 12/12/04
Motion matrices in homogeneous coordinates (need help)
Posted: Jul 10, 1996 12:10 PM
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I have to rotate some images. The usual rotation matrix in homogeneous
coordinates is

cos(angle) -sin(angle) 0
sin(angle) cos(angle) 0
0 0 1

In this case, the rotation center is (0,0) which is in the top left corner of
the image. I'd like the rotation center to be (a, b) and I tried to combine :
a translation (-a, -b), the rotation and a translation (a, b). This gives:

cos(angle) -sin(angle) a( cos(angle)-1 ) - bsin(angle)
sin(angle) cos(angle) b( cos(angle)-1 ) - asin(angle)
0 0 1

This doesn't seem to work! Could you help me?







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