Role of Transients in Two-Bounce Non-Line-of-Sight Imaging
This work provides analytical groundwork for designing future NLOS imaging systems, which is incremental as it builds on existing two-bounce methods by incorporating time-of-flight data.
The paper tackled the problem of improving two-bounce non-line-of-sight imaging by analyzing how time-of-flight measurements reduce the required number of measurements and spatial resolution for shape reconstruction, presenting tradeoffs in temporal resolution, spatial resolution, and image captures with SNR and recoverability functions.
The goal of non-line-of-sight (NLOS) imaging is to image objects occluded from the camera's field of view using multiply scattered light. Recent works have demonstrated the feasibility of two-bounce (2B) NLOS imaging by scanning a laser and measuring cast shadows of occluded objects in scenes with two relay surfaces. In this work, we study the role of time-of-flight (ToF) measurements, \ie transients, in 2B-NLOS under multiplexed illumination. Specifically, we study how ToF information can reduce the number of measurements and spatial resolution needed for shape reconstruction. We present our findings with respect to tradeoffs in (1) temporal resolution, (2) spatial resolution, and (3) number of image captures by studying SNR and recoverability as functions of system parameters. This leads to a formal definition of the mathematical constraints for 2B lidar. We believe that our work lays an analytical groundwork for design of future NLOS imaging systems, especially as ToF sensors become increasingly ubiquitous.