The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » sci.math.* » sci.math

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Motion matrices in homogeneous coordinates (need help)
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  

Posts: 1
Registered: 12/12/04
Motion matrices in homogeneous coordinates (need help)
Posted: Jul 10, 1996 12:10 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

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?

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.