Wesley Smith

Your best bet is to use opengl and a textured videoplane. It's the

most intuitive interface for doing this kind of thing. As for

jit.mxform2d, the parameters are a projective transformation in 2D

with the 3rd column in the help patch the homogenous coordinates,

upper left 2x2 tdiagonal the scale factor, the left 2 cells of the

lower row as the translation, and the upper left 2x2 matrix the

> Thanks for responding, Jean-Francois :-)

> I guess a good way to envision what I want is to give an example :

> Lets say that I want to take a normal 4:3 or 16:9 quicktime movie, and project it so that it fits prefectly on a trapezoidal scrim.

> (i.e. top and bottom parallel, but top maybe 2/3 or so the width of the bottom) I don't want to just crop or mask the image, i want to distort it in jitter to fit the trapezoidal shape of the surface.

> I did look at mxform2d - but the docs don't give any useful examples of how to use it to achieve any particular transformation of the image.. I could try to dig into the math - but it would be great to know if there is a simple way to understand what that function really does :-)

Your best bet is to use opengl and a textured videoplane.  It's the
most intuitive interface for doing this kind of thing.  As for
jit.mxform2d, the parameters are a projective transformation in 2D
with the 3rd column in the help patch the homogenous coordinates,
upper left 2x2 tdiagonal the scale factor, the left 2 cells of the
lower row as the translation, and the upper left 2x2 matrix the
rotation matrix.

On 12/7/06, Valentin  wrote:
>
> Thanks for responding, Jean-Francois :-)
>
> I guess a good way to envision what I want is to give an example :
>
> Lets say that I want to take a normal 4:3 or 16:9 quicktime movie, and project it so that it fits prefectly on a trapezoidal scrim.
>
> (i.e. top and bottom parallel, but top maybe 2/3 or so the width of the bottom) I don't want to just crop or mask the image, i want to distort it in jitter to fit the trapezoidal shape of the surface.
>
> I did look at mxform2d - but the docs don't give any useful examples of how to use it to achieve any particular transformation of the image.. I could try to dig into the math - but it would be great to know if there is a simple way to understand what that function really does :-)
>
> Thanks!
>
> - Valentin
>
>


Jitter Matrix re-shaping/transform?