星载光子计数激光雷达海面点云仿真方法

星载光子计数激光雷达作为一种新的探测体制激光雷达,已开始应用于海面测量。然而受海风等多种因素的影响,海面存在一定的粗糙度和较大的起伏变化,因此光子计数激光雷达返回的信号点云在返回能量和信号光子分布上存在较大的变化,潜在的影响到了海面高程测量精度。本文基于JONSWAP海浪谱和微面元模型理论,结合蒙特卡洛方法建立了光子计数激光雷达海洋目标的仿真模型。以ICESat-2星载光子计数激光雷达的系统参数作为输入,仿真了不同风速条件下海面的信号光子分布,通过与ICESat-2实测结果对比证明了仿真方法的正确性。基于仿真模型,分析了不同风速条件下,光子计数激光雷达的测距误差分布。结果表明,光子计数激光雷达测得的海面高程小于实际参考海面,且测量偏差和标准差随风速增加而增大,当风速为10m/s,累计脉冲次数为100次时,测量偏差约为-2.5 cm,标准差为3.6 cm。所建立的仿真模型和分析结果对优化针对海面观测的星载光子计数激光雷达的系统参数设计和平均海面观测结果修正具有重要的参考意义。

Photon-counting lidar simulation method based on three-dimensional sea surface

With the development and maturity of the photon-counting ldiar technology, photon-counting ldiars are increasingly used in marine mapping. Based on the JONSWAP wave spectrum theory and micro-face model theory, this paper first establishes a photon-counting lidar simulation model via the Monte Carlo method. By substituting the system parameters of a spaceborne lidar into the proposed model, the photon distributions reflected by sea surfaces with different wind speed conditions are simulated and verified by comparing the averaged numbers of photons measured by the ICESat-2 spaceborne lidar. Then, the ranging errors under different wind speed conditions are discussed. The results indicate that the elevation value measured by photon counting lidars will be smaller than the actual elevation of sea surfaces, and the bias and standard deviation of photon counting lidars will increase when the wind speed is rising. When the wind speed is 10 m/s, the cumulative pulse number is 100, the elevation bias is approximately -2.5 cm and the standard deviation is 3.6 cm. The proposed simulation model and analysis results have important reference for optimizing the system parameter design of a photon-counting lidar for sea surface observations and correcting the bias on sea surface observations.