The Wedge Virtual Reality theatre

We describe the history and construction of a stereoscopic projection theatre known as the Wedge. Originally built as a means to introduce supercomputer level visualization facilities into a cash-strapped Australian university, the Wedge has attracted some thousands of visits from the general public. Wedges can now be found in two Australian universities and two museums (visitor centres). Recently, the programming interface to the Wedge has been consolidated and the theatre has become an important part of a new computer science teaching program at the Australian National University (ANU). Genesis of the project Even though the popular image of virtual reality is still one of participants with massive helmets pointing cable-tethered guns at each other, there has been over a decade of development of “immersive” virtual reality theatres where stereo images are projected onto screens surrounding an enclosed space. Many participants at once can view the images by wearing relatively light shutter glasses to filter the correct images to each eye. (This is also the technology used in stereo IMAX theatres.) A lead participant is usually given some means of controlling and interacting with the images. The correct (true) perspective of the images is usually displayed for the head position and orientation of this lead participant. Foremost amongst these immersive theatres is the CAVE [1] theatre that has been closely associated with supercomputing installations in the USA and elsewhere as a means of providing scientists and engineers with a sophisticated means of viewing complicated, multi-dimensional datasets. In the CAVE, images are back-projected onto three walls of a small room and down-projected onto the floor. The perspective is calculated using a “window-projection paradigm” illustrated in Figure 1. In late 1996, we were attending a plasma physics meeting at Argonne National Laboratory in Chicago, USA, and had been encouraged by our local computing experts to visit the CAVE facility there. We were “blown away” by the experience and resolved then and there to build one for ourselves. We were particularly impressed with a simulation of a fish tank where fish would swim from one wall to another in front of the seam between the two screens. This motivated us to build a two-walled theatre which had the junction at centre-stage and where much of the viewing would be in the direction of this vertex with the screens receding from the viewers. This is shown schematically in Figure 2.