A physically based transient simulation framework for non-line-of-sight imaging
Non-line-of-sight (NLOS) imaging reconstructs hidden targets by characterizing indirect light propagation across visible relay surfaces. However, transient imaging typically relies on expensive hardware that is difficult to calibrate and operate. Transient light transport simulation thus serves as an effective alternative, supporting algorithm development, prototyping, and validation before implementing a physical experimental system. This paper introduces a physics-based simulation framework that incorporates bidirectional reflectance distribution function (BRDF) weighting for relay and target surfaces, geometric attenuation, and contact probabilistic sampling. To capture realistic time-delayed photon behavior and system blurring, the framework further integrates a gamma-distribution-based multipath tail model and an optional Gaussian-blurred instrument response function (IRF) module. Simulation and ablation studies validate that the proposed framework can produce high-fidelity and stable transient volume data. In particular, BRDF and multipath tail modeling substantially make the simulated data more consistent with real weak-echo propagation behavior, while the parameterized pipeline achieves a practical trade-off between reconstruction fidelity and computational efficiency.