Snapshot Lidar: Fourier Embedding of Amplitude and Phase for Single-Image Depth Reconstruction

Amplitude modulated continuous-wave time-of-flight (AMCW-ToF) cameras are finding applications as flash Lidars in autonomous navigation, robotics, and AR/VR applications. A conventional CW-ToF camera requires illuminating the scene with a temporally varying light source and demodulating a set of quadrature measurements to recover the scene's depth and intensity. Capturing the four measurements in sequence renders the system slow, invariably causing inaccuracies in depth estimates due to motion in the scene or the camera. To mitigate this problem, we propose a snapshot Lidar that captures amplitude and phase simultaneously as a single time-of-flight hologram. Uniquely, our approach requires minimal changes to existing CW-ToF imaging hardware. To demonstrate the efficacy of the proposed system, we design and build a lab prototype, and evaluate it under varying scene geometries, illumination conditions, and compare the reconstructed depth measurements against conventional techniques. We rigorously evaluate the robustness of our system on diverse real-world scenes to show that our technique results in a significant reduction in data bandwidth with minimal loss in reconstruction accuracy. As high-resolution CW-ToF cameras are becoming ubiquitous, increasing their temporal resolution by four times enables robust real-time capture of geometries of dynamic scenes.