[jitter] Re: IR tracking

Quote: Jean-Marc Pelletier wrote on Wed, 10 October 2007 20:43
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> Quote: seejayjames wrote on Wed, 10 October 2007 20:10
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> It's important to optimize what you can, as cv.blobs etc. use a lot of processing, just by their nature.
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> Not really. cv.jit.label is fairly efficient and either blobs.bounds and blobs.centroids should not be particularly slower than jit.findbounds or cv.jit.centroids. The objects that really eat up CPU time are cv.jit.faces, cv.jit.HS/LKflow and cv.jit.lines.
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> For IR tracking, I had the best results with a few LEDs arranged in a distinctive L-shaped pattern. This allowed me to compute not only the position but the orientation and the slant of the object.
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Jean,

I am  doing a very similar project, which will hopefully be 3 visible LED's (instead of IR), which will be able to give me the x/y position, which I have already managed to do with your cv.jit.label and cv.jit.blobs.centroids objects (these are great by the way!). These LEDs will be mounted on a case which the user will hold, and will press against a fabric frame - the light from the LED lights up areas of the underside of the fabric and the camera tracks these light spots.  I would really like to be able to get orientation data from these 3 spots - so twisting the case clockwse/anticlockwise will produce a value.   I have tried using the cv.jit.direction and orientation objects, but am still a little confused as to their workings.

You say that you mount your LEDs in an L shape, and are able to get the orienation and the slant information out of these. Is this using the cv.jit.orientation or direction object? If I were to mount my LEDs in an isosceles triangle or L shape, would cv.jit.direction be able to calculate the angle of the triangle pointing to it's tip?  Also, I notice you say it computes the orientation of a shape's main axis. If I have got 3 blobs on my screen (in a L shape for example), will it interpret the 3 blobs as 1 shape, or does this object only like to work with 1 shape to start with?  I hope this makes sense :-)

Regards,