On Mar 12, 2004, at 7:29 PM, Max Neupert wrote:
Hi list,
I am working on a project where I want to confront the observer with a projection that changes according to his/her position, thus eliminating the effects of perspective.
So I tried that, the problem is that the object just understands the RGB colorspace, converting the YUV camera stream first seems quite a processing task for the computer.
Actually, pix_movement does work with YUV - get the CVS version of GEM. I wrote an Altivec version of it for PPC. The object is quite fast and uses well under 10% CPU on a 1Ghz G4 running 720x480 video at 30fps.
I succeded in creating a gem patch according to the tutorial patch which does something, but there is no working tracking (see attached patch)
The only problem I see is that you haven't given pix_movement a threshold argument. Send something like 0.1 to the right inlet to make it do it's thing. The only way I've been able to get decent tracking out of movement + blob is to use some sort of data smoothing object like hyperspasm's smooth object or even a plain old GEM average object. Without this the output is too erratic. Also, slow movement works a whole lot better than fast for these objects.
I'm in the process of writing a new luma based tracking object that might get finished beta testing at some point in the near future. It will spit out a grid of 1 and 0 based on the comparing the luma in each grid coordinate to the luma value you are looking for. The output is a generic pd list for you to use in whatever way you see fit.
I've attached a simplified version of your patch.