Re: [Algorithms] Extracting scale from matrix

[Neal T. <ne...@ps...>]

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)

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