Dodecahedron
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Color coded stereo vision in VRML

This application demonstrates a real time adaption of the ChromaDepthTM technology to a VRML model.

Background

Stereo vision is an important cue when viewing three-dimensional environments. It enhances the perception of depth and the sense of space. In principle, each eye is presented a slightly different view of the world. For example, when wearing a head mounted display, each eye has its own screen. The human brain uses the disparity between these views to determine the distance of objects.

The problem, however, with monitor-based 3d graphics (you're probably looking at a monitor right now) is to channel different images to each eye. There were a lot of solutions to this particular problem developed in the past. The equipment most commonly used today are active shutter glasses, sequentially blocking one eye from viewing the monitor while the other eye's image is displayed.

The ChromaDepthTM technology by Chromatek utilizes an even simpler approach. Essentially, the glasses act like an optical prism, the image is shifted by a small amount depending on the wave length of light. Blue is shifted less, red more. As one eye sees the unshifted image, the disparity of both images is greater in red regions than in blue regions, because red light is shifted less then blue. The advantage of images generated using this approach compared to other passive approaches (like overlayed red/blue images viewed through red/blue glasses) is that the image has no disturbing artefacts when viewed without glasses. On the other hand, a disadvantage is the loss of color as an object property.

The VRML model

With the scripting capabilities of VRML 2.0 it was possible to do the translation of object-viewer distance to colors on the fly. For each frame, the color of each vertex in the model is changed according to it's distance to the active viewpoint.

There is a second technique employed in this model - procedural geometry. There are coordinates and indices stored only for the platonic solid. In the initialization phase, holes are cut into each face to give free view into the hollow shape.

Click here to view a VRML 2.0 model of a color coded dodecahedron (5K).

Where to get those glasses

You can buy them at Chromatek. May be you can get them for free, they are occasionally found in magazines, like in the Fall '97 issue of SGI's "Innovation³". The very same glasses are used in Nickelodeon's 3D-Nogglevision.

If you don't have a VRML 2.0 Plugin ...

... you may check out this Quicktime recording of the spinning VRML object.

Credits: Developed by Lars Schumann and Bert Schoenwaelder
Last Update: December 20, 2002, kpb
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