Bernhard Vogl wrote:
> Can you tell us more about it? How did the setup look like? any purpose
> behind it? :-)
Most people you see in the panoramas are GIMP developers. They were in
Montreal for <http://www.libregraphicsmeeting.org/
> at which we (Pablo
d'Angelo, Jim Watters, Alexandre Prokoudine and myself) represented
> (one of them is my first pano with
sound recorded and played)
The purpose of LGM is to promote Open Source image processing software.
The purpose of SAT, a non-profit where the huge display is located, is
to promote artistic use of new technology. The SAT provides synergies
between academic researchers and artists.
Developers and artists were two major groups at LGM and the SAT was
meant to be the conference's dinner venue. Budget restrictions imposed a
change of plan. Nevertheless SAT organized a little extra for us on the
Monday after the conference ended.
I was scheduled to give a show of VR during the dinner. I met with SAT
prior to LGM to prepare for a show on their infrastructure, but ended up
presenting it on a conventional projector during the dinner.
Nevertheless, the contact was positive and so SAT organized a visit
after the end of the official conference.
The cyclorama happened to be the display technology ready for use, and
which I would have used during the dinner. There are other projects
dealing with other forms of 3D display, including a dome and an inversed
dome called panoscope - though these are more for individual experiences
while the cyclorama, as you can see in the VR posted, is for groups.
What is particularly interesting about the cyclorama is that it is all
built with standard components and that the professor who designed the
system intends to publish it soon under an Open Source license.
The hardware is just a bunch of standard XGA projectors connected to a
bunch of standard networked PCs with basic accelerated graphics. It can
project on virtually anything, in this case on a spandex tissue.
The system is amazingly flexible and tolerant of most variables such as
projector positioning, projection surface shape and luminosity, number
of projectors, etc.
A small system can be set up with as little as three projectors, though
to get a meaningful 360° cylinder it takes 7 or 8 of them, and a full
deployment in this class/size is somewhere around 150K-300K $ without
considering that the lamps have to be replaced regularly and that every
change requires a new calibration.
The system uses a lot of principles known in this community from
stitching panoramas, though in inverted sense: overlap between the
projected images is required; the projected images are split along the
seams (as opposed to stitched when producing panoramas) and blended in
real time according to previous established photometric profiles that
take into account irregularities in shape and reflectivity of the
The system requires calibration, a process that is more complex than for
panorama stitching, though with similar principles. Calibration patterns
with control points are projected on the surface and captured by a
mirror lens (almost like the donuts of cheap real estate 360
photography) and an HD video camera (though a digital camera could also
be used, it would slow the process).
The projected image is split by the master computer for each individual
projecting computer, which applies the distorsion, luminosity and
chromatic profile to the partial image before sending it to the
projector, synchronized via the network at each frame.
The Cyclorama is one of many research projects financed by the Canadian
government in the field of 3D visualisation. There are other similar
approaches in other parts of the world.
Interesting times ahead
Copyright © 2007 Yuval Levy
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