While Virtual Reality used to be only a topic for specialised research facilities, now it’s more and more used by industry and slowly entering the daily university routine. Virtual Reality techniques help in product development, but also with complex architectural tasks such as the construction of new production floors.
At the University of Siegen, Germany, the Faculty of Electrical Engineering and Computer Science decided to set up an impressive 3D installation in their Virtual Reality lab: They created a presentation room with an area of about 50 square metres that has room for up to 30 people. This is an absolute novelty, because it is technically quite advanced: A half-cylinder and floor projection in a room about 5 metres in diameter and 2.6 metres in height allows the users to work interactively in a computer simulated, virtual environment.
So far, this was only achieved within CAVE installations or, if a larger spectator group was to be provided for, as a flat screen projection. By using rear projection, the room in Siegen can now be used by both larger groups and small specialist teams without any of its users getting in the path of the projection.
Mounted in four stereoscopic pairs, a total of eight Christie DS+300W projectors are used for the projection onto the cylinder. The floor area is fed by another four Christie DS+300W. These 1-Chip DLP projectors are the predecessors of the new Christie DS+305W models, and like these, they are especially well suited for the 3D environment due to their 10-bit image processing, small footprint and light weight.
They use Infitec stereo technology, a system of special filters placed in front of the lenses and working with the Interference Principle. The signal is being band pass filtered, the key filter quality being selectivity, as this directly affects the image quality in the viewer’s eyes. The viewer sees the image through Infitec stereo glasses, and this fools the user's brain into seeing a three dimenional projection.
The complex equipment has been installed by the projection experts of VISCON, a company who have been selected as the systems integrator directly by Siegen University as part of a public order placement. For cylinder equalization, the VISCON team used a Cine-IPM image processor for non-linear warping and soft-edge blending between the individual projections.
In order to be able to determine the viewer’s position and orientation correctly, the Siegen team are using an ART tracking system with four infrared cameras. Using data from the cameras, the rendering PCs compute the imaging information needed for output, in order to provide an optimum and undistorted 3D image to the viewer.
For this enormous computing power, one master and six rendering PCs have been linked up over a gigabit Ethernet system. Each computer features Intel® Core™2 Duo processors with a 2.67 GHz clock rate and 8GB of memory. Graphics quality is ensured by two NVIDIA graphics adapters with 768 MB memory each. Sound is delivered by a sophisticated 7.1 surround sound equipment.
If asked about the most spectacular moment in the two-week installation phase, Michaela Dierking, Project Manager with VISCON, remembers the moment when the cylinder-shaped back projection screen was hoisted 22 metres high from the outside of the building into the seventh-floor showroom.
Andreas Kolb is the professor responsible for the Siegen 3D laboratory. He holds the chair of Computational Graphics and Multimedia Systems, which was established five years ago. Before that, Kolb has had the opportunity to gain experience with the implementation of 3D projections and simulation studies at Wedel Technical College near Hamburg. The faculty is currently employing 11 scientists, who are also co-operating with other departments. One project, together with the faculty of architecture, deals with three-dimensional room simulations. This project uses OPEN SG software, while the computers used are linked up with the help of a program named Equalizer.
Another project looks into flow simulation. The data for this is being provided by the German Climate Data Centre (DKRZ) in Hamburg. Simply put, they are studying the behaviour of massive particle systems in flow fields. For example: What is the behaviour of smoke passing through a flow? The actual object of research is how to create the corresponding simulation algorithms on graphics hardware.
This type of co-operation influences the utilisation concept of the laboratory, says Professor Kolb: “We consider the lab to be an integration platform. This is why we chose half-cylinder back projection: We wanted to be able to introduce topics to entire groups of spectators, but also to work on interactive projects with just two or three scientists. We do hope, of course, that because of its flexibility, the Siegen 3D lab will be utilised by industry clients too. The first projects of this type have already been started, for example with engineering companies.”