De-noising of distance maps sensed by time-of-flight devices in poor sensing environment

We propose a non-local de-noising approach aimed at filtering range data sensed by Photonic Mixer Device sensors. We address specifically the case of poor sensing environment when the reflected signal amplitude is low. In our approach, signal components of phase-delay and amplitude of the sensed signal are regarded as components of a complex-valued variable and processed together in a single step. This imposes better filter adaptivity and similarity weighting. The complex-domain filtering provides additional feedback in the form of improved noise-level confidence, which can be utilized in iterative de-noising schemes. Pre-filtering of individual components is proposed to suppress structural artifacts. Our approach compares favorably with state of the art approaches.