Forums > Jitter

cornerpin / keystoning of data

May 19, 2009 | 7:29 pm

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 | 8:33 pm

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 | 8:37 pm

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 | 8:41 pm

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

May 19, 2009 | 8:55 pm

thank you, will give it a try.

May 20, 2009 | 11:34 am

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

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

May 20, 2009 | 2:54 pm

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

May 20, 2009 | 2:55 pm

another one

May 20, 2009 | 4:39 pm

thanks a lot

February 4, 2011 | 11:58 pm


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


February 8, 2011 | 8:18 pm

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

and for efficiency, here’s an answer here :

February 13, 2011 | 3:06 pm

Brilliant, thanks for the response :)

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