Free-running vs Synchronous: Single-Photon Lidar for High-flux 3D Imaging

Ruangrawee Kitichotkul, Shashwath Bharadwaj, Joshua Rapp, Yanting Ma, Alexander Mehta, Vivek K Goyal; Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV), 2025, pp. 25972-25982

Conventional wisdom suggests that single-photon lidar (SPL) should operate in low-light conditions to minimize dead-time effects.Many methods have been developed to mitigate these effects in synchronous SPL systems. However, solutions for free-running SPL remain limited despite the advantage of reduced histogram distortion from dead times.To improve the accuracy of free-running SPL, we propose a computationally efficient joint maximum likelihood estimator of the signal flux, the background flux, and the depth, along with a complementary regularization framework that incorporates a learned point cloud score model as a prior.Simulations and experiments demonstrate that free-running SPL yields lower estimation errors than its synchronous counterpart under identical conditions, with our regularization further improving accuracy.