David Powers wrote:
  

Hi everyone,

I bought a cheap Logitech webcam to try motion detection with PD+Gem.
I'm considering, among others things, using this as part of a digital
instrument design.

First of all, the cheap webcam is of course rather noisy. But, the
motion detection doing:

[pix_movement 0.3]
l
[alpha]
l
[pix_blob]

definitely does seem to work okay.

I did a test using the X and Y to control FM synthesis however, and it
mostly worked but tended to produce a lot of noise when something was
moving. What is the recommended way to smooth out the signal a bit?

Also, best way to find the average speed of motion?

Finally, are there more advanced motion detection strategies? Like,
say, could I somehow put a bright red dot on my index finger, and just
detect where my index finger is? I'd love to hear what people have
done.

    

so you want to do color tracking?
simplest thing is to just use the specified color-channel for [pix_blob]
(e.g. [pix_blob 1] should just track the Red channel of an RGB signal
(check the help-patch)).
this only works in trivial cases (red, green, blue, white); for a more
general approach convert the image's colorspace into hsv (with
[pix_rgb2hsv] and mask out all colours you don't want on the
colour-circle (e.g with [pix_curve]) and then track this.

once you only have the pixel of the desired colour, you can of couse
also do motion tracking on the color-filtered image.

i thought i had some example of colortracking added to the gem-examples
(but i might be wrong).


mfg,.asd
IOhannes

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