Hi Carsten, Am 15.08.2014 16:51 schrieb Carsten Neumann <carsten.p.neum...@gmail.com>: > > Hello Michael, > > On 2014-08-15 14:09, Michael Raab wrote: > > If I try to decompose 2 Matrices which are nearly the same I get a > > result scale vector that has switch axis. Here's an example: > > Matrix 1: > > 1.040 -1.040 0.000 0.000 > > 0.707 0.707 0.000 0.000 > > 0.000 0.000 1.000 0.000 > > 0.000 0.000 0.000 1.000 > > Result 1: > > Rotation 0, 0, 45 > > Scale 1.47031, 1, 1 > > Scale Orientation 0, 0, -0.382683, 0.92388 > > Matrix 2: > > 1.046 -1.046 0.000 0.000 > > 0.707 0.707 0.000 0.000 > > 0.000 0.000 1.000 0.000 > > 0.000 0.000 0.000 1.000 > > Result 2: > > Rotation: 0, 0, 45 > > Scale: 1, 1.47986, 1 > > Scale Orientation: 0, 0, 0.382683, 0.92388 > > Has someone an explanation for this? > > assuming that recombining this back into matrices yields the starting > matrices (i.e. it is not a bug in the decomposition) this would be > caused by a degree of freedom in the algorithm.
Does it really produce the initial Matrix? Haven't tested this... > I can think of the following options: > - figure out where this degree of freedom is and make choose the scale > orientation more consistently. Sorry I don't understand this.. > - can you use a ComponentTransform instead of a plain Transform and only > modify the individual components. That would make the decomposed form > the canonical representation and only build the matrix from those. That is not an option as the matrix is the result of a sequence of transformations. > - can you make assumptions about the matrix, e.g. is it composed from > translation, rotation, and (uniform) scale only? Unfortunately not. The only assumption I can think of is that the scale should be applied without any additional scale orientation. Usually I think of transformation matrices as a combination of the 3 components translation, rotation and scale. Actually I do not know where the scale orientation is necessary or useful. Michael > > Cheers, > Carsten > > ------------------------------------------------------------------------------ > > _______________________________________________ > Opensg-users mailing list > Opensg-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/opensg-users ------------------------------------------------------------------------------ _______________________________________________ Opensg-users mailing list Opensg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/opensg-users