Week 7 Summaries
A Practical Multi-viewer Tabletop Autostereoscopic Display
Autostereo display technologies can be divided into three branches, holo-graphics, volumetric, and parallax-based. Parallax-based displays are based on barriers or lenticular lens sheet. By placing barrier sheet at a small distance in front of the display panel, the left and right eyes of a viewer can see different part of pixels of the display surface which enable viewer to see different image s to the left and right eyes. These techniques always rely on head tracking to provide dynamic view positions. In this paper, the authors introduce a practical multi-viewer tabletop autostereoscopic display, which is based on the concept of “Random Hole Display” (RHD).
Their display system consists of a single high-density LSC display panel, a random-hole mask and a Lexan polycarbonate sheet as internal marital. The mask pattern is generated by using the Poisson disk sampling algorithm. There is also a high-accuracy tracking system to track the 3D position of all users’ eyeball. The system’s accuracy is about 5-10mm. The rendering process is divided into four passes. The first pass renders scene from each viewer’s perspective to the frame buffer. The second pass calculates the visibility of pixels by cast rays from the viewpoint through the hole and generates a point image for each viewer. Then these point images are blended into a single texture in the third pass. The error between the blended color and the true color are also calculated in this pass. The final pass diffuses the error to the neighboring visible pixel to improve the image quality.
The authors also developed some interesting application for multi-user interactive collaboration in a tabletop environment. Then they evaluate the image quality improvement by using their error diffusion algorithm. In their system, adding viewpoint will degrade the images. They evaluate this degradation on their different application.
Scape: Supporting Stereoscopic Collaboration in Augmented and Projective Environments.
This paper introduces a collaborative augmented reality system which provides stereoscopic collaboration in augmented and projective environment. Multiple users can observe and interact with a 3D synthetic environment, see the world in their own view as well as conduct face-to-face cooperation. The core display components in their system are head-mounted projective displays (HMPD). HMPD are recognized as good for wide-range of augmented application because it could provide large field of view, lightweight and low distortion optics and correct occlusion of virtual objects by real objects. Using HMPD technology, they built a cave-like room-size space as the shared workspace. Multi-modality interface devices, including an optical tracking system, a magnetic tracking system and so forth, are used to improve the experience of interaction and collaboration in 3D environment. The authors also developed a cross-platform application programming interface (API) to provide high- and medium-level control over the Scape system. At last, the authors introduce an application example called “Aztec explorer”.
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