cornerpin / keystoning of data

May 19, 2009 at 7:29pm

cornerpin / keystoning of data

Its simple but I cant get my head around it:
I try to do the classic cornerpin / keystoning of a skewed
rectangular (projection). Instead of skewing video I want incoming
x,y values to be mapped to the new skewed rectangular.
Does that make sense?
Can anyone direct me into the right direction?

May 19, 2009 at 8:33pm

corner pinning is not exactly simple.

here is a patch using gl.nurbs to get you started. you could also use gl.mesh. basic idea is to adjust the celss of a 2×2 matrix to move your corners.

a simple “corner pin” search will turn up a few other techniques.

– Pasted Max Patch, click to expand. –
May 19, 2009 at 8:37pm

Thanks a lot for the quick help,
is there any chance to get a patch which works in 4.6?
All the best

May 19, 2009 at 8:41pm

here’s the sreenshot. should be all you need.

May 19, 2009 at 8:55pm

thank you, will give it a try.

May 20, 2009 at 11:34am

Thats great, I made the patch and it does exactly what I meant with a video texture. I wonder if there is any way to send a x,y coordinate (position) of a matrix to the and get the altered “nurbed” x,y position.

May 20, 2009 at 12:20pm
May 20, 2009 at 1:10pm

Cheers, do you have a screenshot or 4.6 patch of that link?

May 20, 2009 at 2:54pm

May be somebody can convert it to 4.6 ?
Hope it helps!

May 20, 2009 at 2:55pm

another one

May 20, 2009 at 4:39pm

thanks a lot

Feb 4, 2011 at 11:58pm


I have just been experimenting with corner pinning this evening, and would really appreciate it if someone could explain the difference between using nurbs as in this example, compared to a mesh as discussed here:

I notice that there isn’t a need to scale the control matrix bigger than 2×2 as there is with the mesh, so is it simply that nurbs take care of themselves with regards to mapping properly? Is the outcome mapped identically?

Many thanks


Feb 8, 2011 at 8:18pm

effectively it seems you don’t need more than a matrix 2×2 with

and for efficiency, here’s an answer here :

Feb 13, 2011 at 3:06pm

Brilliant, thanks for the response :)


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