# Fast online 3D reconstruction of dynamic scenes from individual single-photon detection events

## TL;DR

This paper introduces a real-time 3D reconstruction algorithm for dynamic scenes using single-photon detection events, enabling fast processing without histogram construction and handling rapid scene changes efficiently.

## Contribution

It presents a novel Bayesian method that processes individual photon detection events online, bypassing traditional histogram-based approaches for dynamic 3D scene reconstruction.

## Key findings

- Processes hundreds of frames per second
- Handles dynamic scenes with high robustness
- Achieves real-time 3D reconstruction without histograms

## Abstract

In this paper, we present an algorithm for online 3D reconstruction of dynamic scenes using individual times of arrival (ToA) of photons recorded by single-photon detector arrays. One of the main challenges in 3D imaging using single-photon Lidar is the integration time required to build ToA histograms and reconstruct reliable 3D profiles in the presence of non-negligible ambient illumination. This long integration time also prevents the analysis of rapid dynamic scenes using existing techniques. We propose a new method which does not rely on the construction of ToA histograms but allows, for the first time, individual detection events to be processed online, in a parallel manner in different pixels, while accounting for the intrinsic spatiotemporal structure of dynamic scenes. Adopting a Bayesian approach, a Bayesian model is constructed to capture the dynamics of the 3D profile and an approximate inference scheme based on assumed density filtering is proposed, yielding a fast and robust reconstruction algorithm able to process efficiently thousands to millions of frames, as usually recorded using single-photon detectors. The performance of the proposed method, able to process hundreds of frames per second, is assessed using a series of experiments conducted with static and dynamic 3D scenes and the results obtained pave the way to a new family of real-time 3D reconstruction solutions.