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?
Cheers
Torsten


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
Torsten


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 jit.gl.nurbs and get the altered "nurbed" x,y position.
Cheers
Torsten


May 20, 2009 | 12:20 pm

some ideas about "corner pin" GUI here
http://www.cycling74.com/forums/index.php?t=msg&goto=168791&rid=0&srch=crop#msg_168791


May 20, 2009 | 1:10 pm

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


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

Hello

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: http://www.cycling74.com/forums/topic.php?id=18017#post-95512

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

DiGiTaLFX



FP
February 8, 2011 | 8:18 pm

effectively it seems you don’t need more than a matrix 2×2 with jit.gl.nurbs

and for efficiency, here’s an answer here : http://cycling74.com/forums/topic.php?id=27497


February 13, 2011 | 3:06 pm

Brilliant, thanks for the response :)


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