Super-resolved time-of-flight sensing via FRI sampling theory

• Published in: Proceedings of the ... IEEE International Conference on Acoustics, Speech and Signal Processing (1998) pp. 4009 - 4013
• Main Authors: Bhandari, Ayush, Wallace, Andrew M., Raskar, Ramesh
• Format: Conference Proceeding Journal Article
• Language: English
• Published: IEEE 01.03.2016
• Subjects: Algorithms; Backscattering; Boolean functions; Data structures; Echoes; Electronics; Finite-rate-of-innovation; Global Positioning System; Hafnium compounds; Light reflection; multi-path; Optical communication; Optical fibers; Sampling; sampling theory; Sensors; Signal resolution; super-resolution; Time-frequency analysis; time-of-flight imaging
• ISSN: 2379-190X
• DOI: 10.1109/ICASSP.2016.7472430

Optical time-of-flight (ToF) sensors can measure scene depth accurately by projection and reception of an optical signal. The range to a surface in the path of the emitted signal is proportional to the delay time of the light echo or the reflected signal. In practice, a diverging beam may be subject to multi-echo backscatter, and all these echoes must be resolved to estimate the multiple depths. In this paper, we propose a method for super-resolution of optical ToF signals. Our contributions are twofold. Starting with a general image formation model common to most ToF sensors, we draw a striking analogy of ToF systems with sampling theory. Based on our model, we reformulate the ToF super-resolution problem as a parameter estimation problem pivoted around the finite-rate-of-innovation framework. In particular, we show that super-resolution of multi-echo backscattered signal amounts to recovery of Dirac impulses from low-pass measurements. Our theory is corroborated by analysis of data collected from a photon counting, LiDAR sensor, showing the effectiveness of our non-iterative and computationally efficient algorithm.