[ros-users] Prosilica GC1020

[René Wagner]

Hi Koen,

On Thu, 2010-10-14 at 10:18 +0200, koen buys wrote:
> >> > Next on my list is getting two GC1020s to work in a stereo setup. I
> >> > don't know when I'll get around to that yet, though.
> >>
> >> Here I believe that your main problem will be getting the timestamps
> >> from the two cameras to exactly match. I have heard that there is a
> >> node to do this, but am not sure off-hand what it is called. It is on
> >> a non-WG repo.
> >
> > I vaguely remember this being mentioned on the mailing list now. I'll
> > check the archives later today.
> >
> 
> If you found it, could you post the topic?

I think this is the message I remembered:

http://code.ros.org/lurker/message/20101007.133812.c45bb049.en.html

I haven't looked at the code yet, though.

> We are currently doing a similar setup, the camera's are configured to
> be triggered
> externally or one triggers the other, but still the timing doesn't match, the
> images do match.

I wouldn't expect the timestamps to match exactly. We typically see
timestamp differences of about 10-200 microseconds with both GC1020s
connected via dedicated GigE cards and one realtime thread per camera on
a quadcore machine (using our own software framework).

> I'm interested in collaborating in a joint package setup.

Supposedly, the easiest way to get a working setup is to have an
intermediary node assign the earlier of the two timestamps to both
frames (assuming that frame correspondence is known). A more
sophisticated approach would involve some sort of external observation
of latencies and/or filtering on the timestamps.

Cheers,

Rene

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Dipl.-Inf. René Wagner                     Junior Researcher
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