[Beowulf] cluster for doing real time video panoramas?

Bogdan Costescu Bogdan.Costescu at iwr.uni-heidelberg.de
Thu Dec 22 11:42:12 EST 2005

On Thu, 22 Dec 2005, Jim Lux wrote:

> But maybe, 3-4 real wide angle cameras (perhaps shining the camera
> into a curved reflector (think christmas tree ornament) to give
> spherical situational awareness,

You'd need extra transformations afterwards from spherical to plane.  
The cost for the extra CPUs and networking to do this might be higher
than the cost of a few cameras :-)

> Or, for the more technically inclined.. go get one of those nifty
> 2.4GHz wireless cameras and tape it to the top of a toy radio
> controlled car.  Attempt to drive the car by looking only at the
> video screen, without having any visibility of the car.

I've done this some years ago and I managed quite well, maybe because
I have a good visual memory and the environment was quite static. Only 
when a second similar toycar came into play things became difficult.

> I wonder how one could hook up all cameras to all nodes (cheaply)..
> If you wanted to parallelize the rendering on a frame by frame
> basis, you'd need to stream the video from all cameras to all
> processors.

Why not using one or a few head nodes that do only the data
aquisition, maybe decompression (if not raw image data) and alignment
of data such that the next operations would be optimized from a memory
access point of view. Then they would send each frame to a different 
compute node in a round-robin fashion or based on load.

Another idea: AFAIK FireWire should allow a device to be access from
more than one computer - I don't know how well this works in practice
and if there are any constraints that would make it impractical for
this application (f.e. that would result in delaying frames). All the
computers that would need to access data from a certain camera would
need to be daisy-chained - this introduces a hard partitioning. A
workaround would be to have all cameras and all computers being
daisy-chained, but this would put a limit on the number of cameras
that can be connected. As a benefit, using FireWire (either way) would
eliminate the need of frames transfer between a head node and a
compute node so the network setup might be easier.

Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De

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