Week 7 : summaries
A Practical Multi-viewer Tabletop Autostereoscopic Display
Auto stereoscopic displays provide stereo perception without using glasses. The Random Hole Display inspires the system. RHD proposes a dense pattern of tiny, pseudo-randomly placed holes. Hence, multiple viewers at multiple locations will see multiple views. But those kinds of system are only calibrated for four users’ position and have serious issues with interference. The paper presents an enhancement of RHD using hardware-accelerated algorithm and viewer tracking.
The system consists of one high-resolution lcd screen that has on his screen surface a mask that contains holes. One issue with randomly distributed holes is they do not perfectly overlap pixels. Indeed, one hole can touch to four pixels. User tracking permit to compute exactly what a user will see and then what values apply to pixels.
Because visible pixels are divided into users, one user will not have more than eight percent of the resolution. So, a pre-filtering is applied to the image to decrease the resolution and increase the computation speed.
To decrease the impact of pixels shared by users, the authors have developed a neighborhood error diffusion algorithm. Around conflicting pixels, pixels’ colors are adjusted to attenuate its impact.
The rendering uses hardware-accelerated algorithm. First the image is sampled. Then, the subset of visible point in each image is generated. Once completed, points are blends into a texture. Finally, the error diffusion algorithm is applied.
Scape: Supporting Stereoscopic Collaboration in Augmented and Projective Environments
There are a lot of efforts made to support local and remote collaboration in 3D environment. If there exists several approaches for enhanced 3D collaboration, the system described in the paper, Scape, uses devices based on Head-Mounted Devices. The typical eye-piece-type optics are replaced with projective lenses. A retro-reflective screen also replaces the display screen. A beam splitter is used to merge images. Such devices are called HMPDs and provide large field of view, low distortion optics and correct occlusion. The idea of scape is to uses retro-reflective surface and HMPDs to offers a collaborative environment. Retro-reflective surfaces only tolerate small angles. Then, HMPDs’ fov does not have to exceed 80 degrees. The light intensity receives by the pupil is only about a quarter of its normal intensity because it passes multiple times through the beam. But the biggest advantage of the system is retro-reflective surface can be placed at any location without causing blur or degrading image quality.
Scape also provides different interfaces to interact. Generic devices such mouse or keyboard can be used. In addition, a set of unique devices has been developed, with among them, a glove that tracks the hand position.
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