TR2008-028
| Non-Refractive Modulators for Encoding and Capturing Scene Appearance and Depth | |||
| Citation: | Veeraraghaven, A.; Agrawal, A.; Raskar, R; Mohan, A.; Tumblin, J., "Non-Refractive Modulators for Encoding and Capturing Scene Appearance and Depth", IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR), June 2008 (IEEE Xplore) | ||
| Date: | July 2008 | ||
| MERL Contact: | Amit Agrawal | ||
We analyze the modulation of a light field via non-refracting attenuators. In the most general case, any desired modulation can be achieved with attenuators having four degrees of freedom in ray-space. We motivate the discussion with a universal 4D ray modulator (ray-filter) which can attenuate the intensity of each ray independently. We describe operating of such a fantasy ray-filter in the context of altering the 4D light field incident on a 2D camera sensor. Ray-filters are difficult to realize in practice but we can achieve reversible encoding for light field capture using patterned attenuating mask. Two mask-based designs are analyzed in this framework. The first design closely mimics the angle-dependent ray-sorting possible with the ray filter. The second design [17] exploits frequency-domain modulation to achieve a more efficient encoding. We extend these designs for optimal sampling of light field by matching the modulation function to the specific shape of the band-limit frequency transform of light field. We also show how a hand-held version of an attenuator based light field camera can be built using a medium-format digital camera and an inexpensive mask. | |||
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