[PD] video processing removing feedback

Damian Stewart damian at frey.co.nz
Tue Aug 19 19:13:35 CEST 2008

Joseph Barrows wrote:
> hi all,
> I would like some advice, i wish to track objects using a video camera
> and pd/gem (easy enough) but I would then like to project video into
> that same space, but avoid it interfering with the video object
> processing.  is there some simple way to do: (live video) - (gem
> generated video) = video used for blob tracking ?
> (if there is some way to offload it to the gpu that would be good too)

use infrared lighting and cameras. (this also gives you the advantage that 
you can flood the projection area with invisible infrared light, which is 
great for tracking, while keeping the 'real' visible lighting to a minimum).

most security cameras based on CCDs already detect infrared. if you put a 
piece of exposed and developed camera print film (just ordinary film) 
between the lens and the CCD, this blocks visible but allows infrared light 
through. to make a super cheap infrared light from a theatre light or any 
incandescent light, put 2-3 layers of Congo Blue theatre lighting gel and 
one layer of Primary Red gel in front of the light. be careful, it gets 
very hot.

damian stewart | +31 6 5902 5782 |  damian at frey.co.nz
frey | live art with machines | http://www.frey.co.nz

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