RE: [Algorithms] Extracting scale from matrix
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RE: [Algorithms] Extracting scale from matrix
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From: <bse...@ro...> - 2000-09-07 18:53:04
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Isn't there a DecomposeMatrix routine in one of the Graphics Gems? Pass it a 4x4 matrix and it returns rotation, scale, translation, shear and probably something more... ...yeah, it's at page 207 of Graphics Gems 4. -Blake -----Original Message----- From: Neal Tringham [mailto:ne...@ps...] Sent: Thursday, September 07, 2000 10:18 AM To: gda...@li... Subject: Re: [Algorithms] Extracting scale from matrix De: Jon Anderson [mailto:jan...@on...] >Are there any good tricks for extracting the scale (x, y, z) from a 4x4 >matrix? It seems pretty trivial to do it for matrices that consist of >rotations about a single axis, but I'm having problems doing it for more >complex matrices. If your matrix contains only rotation, scale and translation information, could you extract the scale factors by comparing the length of the basis vectors to the length of the normalised basis vectors? Note that (even if this works:-)) I don't believe it would allow you to distinguish between a negative sign in a scale factor (a "mirror") and a rotation, i.e. it would only allow you to extract the magnitude of the scale factors, not their signs. Curious as to people's comments on this... Neal Tringham (Sick Puppies) ne...@ps... ne...@em... _______________________________________________ GDAlgorithms-list mailing list GDA...@li... http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list |
