Multi-Path Interference Mitigation For Indirect Time-of-Flight Camera By the Distortion of Coding Curve

Abstract

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The indirect time-of-flight camera measures depth based on the phase shift between modulated laser and its reflected light. However, when there are multi-paths due to interreflections, depth estimation is significantly affected as it assumes that only a single reflected light is observed. In this paper, we propose a method for mitigating multi-path interference utilizing coding curves derived from measurements of multiple sensor taps, which represent the contribution of global light component, i.e., multi-path. First, to obtain the coding curve, we offset the laser light to the sensor and measure the sensor tap values for different delays. We propose a data-driven method for mitigating MPI, utilizing a dataset where distorted coding curves are paired with MPI intensity. By using the measured coding curve as a query to obtain correction values from the dataset, we can mitigate the effect of MPI and obtain the correct depth. Unlike previous methods, our approach can solve the general MPI problem while imposing fewer restrictions on the type of reflections, the number of light paths, and the modulation frequency. We validate the effectiveness of our method through both simulation and real experiments.