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Index › Programming Questions & Help › Video Capture,  Movie Playback,  Vision Libraries › tracking 4 points, adjusting overlay image
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tracking 4 points, adjusting overlay image (Read 942 times)
posiXtom
tracking 4 points, adjusting overlay image
Mar 8th, 2010, 8:21am  
Hi guys,

here's what I want to do:

i want to map 4 points on a canvas i'm filming in real time (the 4 corners)
then I want to overlay this with an other partially transparant image which adjusts and distorts according to the filmed image.
a bit like with Augmented reality.

i may be searching with the wrong keywords... can't come up with anything useful.

end result will be an exibition of canvasses, which, when filmed, display another layer on top of them..
thx!
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koogy
Re: tracking 4 points, adjusting overlay image
Reply #1 - Mar 8th, 2010, 10:07am  
there is a keystone library if that's any use

http://processing.org/discourse/yabb2/num_1252422184.html

http://keystonep5.sourceforge.net/

or this

http://processing.org/discourse/yabb2/?num=1263582239/5
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posiXtom
Re: tracking 4 points, adjusting overlay image
Reply #2 - Mar 8th, 2010, 11:31am  
i think i poorly explained myself.

what i want to do is actually the same as an AR tag,
but with the AR tag, it's very wobly and buggy,

so i thought when i track the 4 corners, i can stabilize the image.
i don't want to project onto anything.

just film it, and the filmed image should have an extra layer added to it.
is that an ok explanation?

thx for your input though, i'm glad somebody reacted so fast.
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naus3a
Re: tracking 4 points, adjusting overlay image
Reply #3 - Mar 9th, 2010, 2:09am  
if the canvas you're trying to track is painted you can transform the painting into an AR marking using a feature based tracking algorithm like SURF (there's a SURF library for processing in the libraries page).

if you're working on white canvas I'd threshold properly and then I'd look for rectangular contours using opencv.
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pulse
Re: tracking 4 points, adjusting overlay image
Reply #4 - Mar 9th, 2010, 9:58am  
Here is question which is realted to the original querie: It will be simply great if you guys can give some idea.

During AR traching each marker has its own coord system(PMatrixes), how can we draw a line (for example)between the markers? HOw can we get the co-ords of each of the markers with respect to the main coord system of processing?

When using push pop we can easily handle this but how do we do when uding AR library? Can we have two coord system in processing and connect between the two; I am not able to get the coordinates of a point with respect to another cooprdinate system. Is there some kind of transformation matrixes by which this can be done.

Thanks
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