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?
Cheers
Torsten

#43996
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. –
#158018
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
Torsten

#158019
May 19, 2009 at 8:41pm

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

#158020
May 19, 2009 at 8:55pm

thank you, will give it a try.

#158021
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 jit.gl.nurbs and get the altered “nurbed” x,y position.
Cheers
Torsten

#158022
May 20, 2009 at 12:20pm
#158023
May 20, 2009 at 1:10pm

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

#158024
May 20, 2009 at 2:54pm

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

#158025
May 20, 2009 at 2:55pm

another one

#158026
May 20, 2009 at 4:39pm

thanks a lot

#158027
Feb 4, 2011 at 11:58pm

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

#158028
Feb 8, 2011 at 8:18pm

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

#158029
Feb 13, 2011 at 3:06pm

Brilliant, thanks for the response :)

#158030

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