Hi Mark and Yohan
thank you for your quick answer for the two solutions of the problem. These
are exactly the same two ideas of mixing the CG with the signal of the
camera I had, before sending my mail: the first is to mix the signals
outside the computer with the scan converter, the other is to mix the
signals inside the computer ( I did not knew, that the ARToolkit can manage
this). I think, both methods have their advantages and disadvantages. The
first solution does not use the computer for mixing, thus the computer has
more free resources. It also seems to me, that this solution is good for
high frame rate and high resolution of the video signal.
The second solution has the advantage, that one can use the video signal to
detect real objects in the video stream, such that the computer graphics can
be covered by the real objects, if the cg is behind the real object in the
Therefore I have some more questions:
1. Which of these solutions is also cappable of managing stereo video input
2. Which camera type should one choose for the different solutions.
3. Which solution is easier to calibrate?
4. In your perspective: which solution do you prefer?
Thank you a lot
Von: Mark Billinghurst [mailto:grof@h ..................]
Gesendet: Mittwoch, 10. Oktober 2001 02:02
An: arforum@t .........
Betreff: Re: [ARFORUM] Mixing Video an CG in realitme
We have that working with the current version of the ARToolKit software we
are developing here at the HIT Lab. We have a laptop with firewire video
input that can capture video frames at 30fps. Then we render 3D computer
graphics on the ARToolKit tracking markers.
We have not released this into the public domain yet, but should be able
to do so by the end of October. It'll be put onto the ARToolKit website -
With this software there is no programming needed appart from the 3D
graphics application code - ARToolKit takes care of the tracking and video
compositing for you.
The laptop we are using has a GeForce2 Go chip in it which is a pretty low
end GeForce card (17 million polygons/sec), so practically and GeForce
card would do the trick..
Please let me know if you have any questions about this..
On Tue, 9 Oct 2001, Stefan Gruen wrote:
> Hello everybody,
> for building a video-see through AR-system I have the following problem.
> Suppose, that I want to overlay the video stream of a fire wire camera in
> realtime with the computer graphics which my computer produces. One idea
> would be to mix video stream and the computer graphics in the computer and
> connect the HMD to the graphics card. What kind of graphic cards do you
> recommend for mixing (sorry: no SGI). And much more important: is there
> software with which I can mix the video stream and the computer graphics
> realtime? Or do I have to program it for my self?
Mark Billinghurst | Human Interface Technology Laboratory
grof@h .................. | University of Washington, Box 352-142
fax: +1-206-543-5380 | Seattle, WA 98195
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