Week 7 Summaries

 Scape

A 3D, interactive, collaborative, virtual environment is discussed in the paper. In this research an attempt to bridge the gap between virtual and augmented reality paradigms is met with success. This is achieved using range of devices such as Head Mounted Projective Displays, workbench, walled display, tracked objects in the room, magnetic trackers, DataGlove  and custom designed widgets.

Previous work on collaborative VR has limitations of high cost and inability to extend to more than one user without hampering performance. For the Scape project they’ve used HMPD technology which uses projective lens. HMPD provides 3D computer generated information, can create arbitar number of users and retains face to face communication. The Shared 3D workspace provides both exocentric as well as egocentric perspectives. The limitations includes the angular orientations and characteristics of the retro-reflective material. While designing the environment some considerations have to be made in terms of screen size, screen position, cross talk, functional augmentation, field of view, lightning and portability.

The hardware for implementation included retro-reflective material on workbench and walls and a range of trackers. On the software side the toolkit is modular and extensible and employs client server architecture. For the demonstration and  application called Aztec Explorer was developed. For this a 3D model of Aztec city was rendered. The users could either discuss Aztec’s plan or explore it via walk through.

For the future work some important aspects such as miniaturizing HMPD, improvement upon interface design and adding more physical widgets is mentioned.

 

Autostereoscopic Display

 The paper discusses about a system developed upon Random Hole Display (RHD). One major problem in RHD is the handling conflicting pixels which appear when two or more users view the display simultaneously. Several solutions for the problems are introduced and one is discussed in the paper.

While autostereoscopic displays do not need users to wear any special glasses, one major problem with them is the price/performance ratio. The three main autostereo displays are holographic, volumetric and parallax-based. This system is developed by enhancing RHD.  The hardware includes LCD/LED panels, optical trackers, etc.  For rendering the existing problems are tackled using algorithms, blending techniques and developing a  4 pass hardware accelerator algorithm.  In first pass, scene from viewer’s perspective to the frame buffer is rendered.  Then the visibility of pixels is calculated by cast rays. These point images are then blended into a single texture in the third pass. The error to the neighboring visible pixel is diffused in the final pass. An application called city-scape was developed. It was observed that image quality degraded by additional viewpoints.

For future work, use of brighter and high density screens is proposed.

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