Pseudo-Passive Indoor ToF Sensing exploiting Visible Light Communication Sources

The need for active illumination is one of the fundamental downsides of state-of-the-art Time-of-Flight (ToF) cameras and translates into large power consumption as compared to passive imaging modalities. Recently, developments in visible light communications (VLC) have allowed the lighting infrastructure to provide both illumination and communication services in indoor environments. In this paper, we propose exploiting visible light sources as opportunity illuminators for indoor ToF sensing. This allows for drastically reducing the power consumption of the ToF camera, as the need for illumination modules is eliminated. We study the feasibility of this idea using an off-the-shelf VLC module, model the emitted light signal, and study its autocorrelation properties. We show that the prominence of two dominant frequencies, arising from the underlying clock signal and coding scheme, enables CW-ToF operation. Simulations carried out using real signals from the VLC module showed successful depth estimation, up to an offset, using standard methods for CW-ToF depth estimation such as the four-phases algorithm.