miko

02-27-2003, 12:12 AM

i've got a trnasformation matrix and i've got coordinates of vetex after that matrix has been applied on it. is it possible to doetermine original vertex coordinates?

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miko

02-27-2003, 12:12 AM

i've got a trnasformation matrix and i've got coordinates of vetex after that matrix has been applied on it. is it possible to doetermine original vertex coordinates?

roffe

02-27-2003, 12:24 AM

v' = Mv

v = M^-1 * M * v

If your transformation matrix is non-singular(determinant != 0) then yes. Determining the inverse can be difficult though. It all depends what you start out with...

v = M^-1 * M * v

If your transformation matrix is non-singular(determinant != 0) then yes. Determining the inverse can be difficult though. It all depends what you start out with...

MichaelNewman

02-27-2003, 02:07 PM

I think the above should be:

u - initial position

v - final position

v = M * u

u = M^-1 * v

Determining the inverse of a matrix is a rather complicated process. Try to google it and look for the formula based on Cramer's rule. Keep in mind that calculating the inverse of a matrix is really computationally expensive and so you don't want to do it too often.

u - initial position

v - final position

v = M * u

u = M^-1 * v

Determining the inverse of a matrix is a rather complicated process. Try to google it and look for the formula based on Cramer's rule. Keep in mind that calculating the inverse of a matrix is really computationally expensive and so you don't want to do it too often.

miko

02-27-2003, 02:22 PM

yeah, everything works cool... all needed inverse matrices are computed during initialization so ist's pretty fast

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