Research Article

Underwater 3D target detection: Semi-analytic Monte Carlo model and UAV-based scanning lidar system

¹ Aerospace Laser Technology and System Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, PR China
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, PR China
³ Wangzhijiang Innovation Center for Laser, Aerospace Laser Technology and System Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, PR China
⁴ School of Physical Science and Technology, Shanghai Tech University, Shanghai 201210, PR China
⁵ Naval Research Institute, Tianjin 300061, PR China
⁶ Laoshan Laboratory, Qingdao 266237, PR China

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 November 2025
Accepted: 3 January 2026

Abstract

Lidar has been widely applied in marine research due to its strong penetration capability in water. To study the lidar detection of underwater targets, a semi-Monte Carlo model of target detection (MCT) is developed to simulate the scanning signals, incorporating three-dimensional interaction processes between the beam and the target, the wind-driven surface waves and stratified water columns. A UAV-based linear scanning oceanic lidar system (SOL) is developed for model validation. The model is validated by the lidar equation results with a less than 5% mean relative error within the upper 50 m, and further confirmed by the SOL field experiments through consistent target localization. The detection capabilities of SOL are analyzed based on the MCT model for Jerlov II and Jerlov 3C water types, and an extended detection range is introduced to evaluate the variation of horizontal scanning resolution with target depth, providing guidance for balancing detection capability and efficiency under varying conditions.