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Posted by dan michaels on March 5, 2007, 2:53 pm
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> dan michaels wrote:
>
> > I imagine there are people around here who have used both of these
> > devices.
>
> > I picked up an AVRcam this week, and started playing with it. The
> > thing sends out a "torrent" of data in ET = color-blob tracking mode,
> > at 115.2K. Pretty cool to follow using AVRcamView, but difficult I
> > think for a PIC/etc to interpret.
>
> I don't have much experience with either, but I do dabble in some other
> video-enhanced technologies (mostly on the PC side), and what we often
> do there is simply grab what we can, and ignore the frames inbetween if
> there is a bottleneck. Even though the camera may be supplying 30 fps,
> there is no steadfast rule that you have to process all 30 frames each
> second. Your application may only need two frames a second, and that may
> be all that your hardware can support. Take whatever time you need to
> process the data, and forget the other 28 frames.
>
> Anyway, you'd think the newer DSP-based PICs would have the speed to
> process the data. No?
>
> -- Gordon
Hi Gordo. Actually, the AVR cam [like the CMU cam, as I understand it]
doesn't send complete frames to the PC. That takes 4-sec each at
115.2. These cams are basically just blob-trackers.
What the cam does is process the frames in real-time and extracts 8
colored areas [blobs], as determined by a preset color map, and just
sends over the x-y coordinates of upper left and lower right corners
of the blob areas, so maybe just 20 or 30 bytes at 30 times/sec or
so. Then the PIC/cpu converts this coordinate data as it sees fit.
In the PC viewer software that comes with the cam you can watch the
blob detection in real-time. You see a torrent of 8 squares
representing the blobs flashing on the screen at 30/sec.
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> I imagine there are people around here who have used both of these
> devices.
>
> I picked up an AVRcam this week, and started playing with it. The
> thing sends out a "torrent" of data in ET = color-blob tracking mode,
> at 115.2K. Pretty cool to follow using AVRcamView, but difficult I
> think for a PIC/etc to interpret.