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Optical Engineering

Interframe consistent multifrequency phase unwrapping for time-of-flight cameras
Author(s): Ouk Choi; Seungkyu Lee; Hwasup Lim
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Paper Abstract

Commercially available time-of-flight cameras illuminate the scene with amplitude-modulated infrared light signals and detect their reflections to provide per-pixel depth maps in real time. These cameras, however, suffer from an inherent problem called phase wrapping, which occurs due to the modular ambiguity in the phase delay measurement. As a result, the measured distance to a scene point becomes much shorter than its actual distance if the point is farther than a certain maximum range. There have been multifrequency phase unwrapping methods, which recover the actual distance values by exploiting the consistency in the disambiguated depth values across depth maps of the same scene, acquired at different modulation frequencies. For robust and accurate estimation against noise, a cost function is built that evolves over time to enforce both the interframe depth consistency and the intraframe depth continuity. As demonstrated in the experiments with real scenes, the proposed method correctly disambiguates the depth measurements, extending the maximum range restricted by the modulation frequency.

Paper Details

Date Published: 15 May 2013
PDF: 13 pages
Opt. Eng. 52(5) 057005 doi: 10.1117/1.OE.52.5.057005
Published in: Optical Engineering Volume 52, Issue 5
Show Author Affiliations
Ouk Choi, Samsung Advanced Institute of Technology (Korea, Republic of)
Seungkyu Lee, Kyung Hee Univ. (Korea, Republic of)
Hwasup Lim, Korea Institute of Science and Technology (Korea, Republic of)

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