Phasor field diffraction based reconstruction for fast non-line-of-sight imaging systems

Non-line-of-sight (NLOS) imaging recovers objects using diffusely reflected indirect light using transient illumination devices in combination with a computational inverse method. While capture systems capable of collecting light from the entire NLOS relay surface can be much more light efficient than single pixel point scanning detection, current reconstruction algorithms for such systems have computational and memory requirements that prevent real-time NLOS imaging. Existing real-time demonstrations also use retroreflective targets and reconstruct at resolutions far below the hardware limits. Our method presented here enables the reconstruction of room-sized scenes from non-confocal, parallel multi-pixel measurements in seconds with less memory usage. We anticipate that our method will enable real-time NLOS imaging when used with emerging single-photon avalanche diode array detectors with resolution only limited by the temporal resolution of the sensor. Current implementations of non-line-of-sight imaging use reconstruction algorithms that are difficult to implement fast enough for real-time application using light efficient equipment. The authors present an algorithm for non-line-of-sight imaging that is low complexity and allows fast and efficient reconstruction on a standard computer.