【作者】 罗敏；

【导师】 周辉；

【作者基本信息】 武汉大学 ， 光学工程， 2020， 硕士

【摘要】 具备波形记录功能的星载激光测高仪是一种新型的主动式遥感设备,它能够接收被测目标的反射脉冲回波信号。星载激光测高仪所采集的接收脉冲回波与目标几何特征参数之间存在对应关系,通过对该接收脉冲回波信号的处理与分析,可以反演得到目标的距离、高度、倾斜度和粗糙度等几何信息。因此,星载激光测高仪被广泛应用在海洋学、生态学、地形学、冰川学等等领域,开发一种普适性的接收脉冲回波数据的处理算法是保障这些领域内的目标信息反演精度的关键所在。目前,已公布的接收波形数据处理方法主要是在假设接收回波由多个高斯分量混合而成,利用拐点法与非线性最小二乘拟合相结合的方式来实现波形参数的提取,这些方法对非高斯分量或分量存在明显混叠的波形处理效果较差,针对这些方法存在的局限性,本论文主要开展了以下几个方面的研究工作:(1)基于星载激光测高仪接收脉冲回波信号的产生原理,推导了多模式回波的理论表达形式,通过回波的仿真分析确定以偏正态模型作为回波处理的拟合模型;(2)根据星载激光测高仪多模式回波信号的分布特点,提出一种基于梯度下降的波形逐层分解方法(Waveform Decomposition on Gradient-descent and Levenberg Marquardt,WDGLM)的回波数据处理算法;(3)利用WDGLM回波数据处理算法对仿真模拟的回波数据和实际采集的回波数据进行了处理分析,并以回波的拟合残差和相关系数作为评判回波处理结果优劣的指标。通过对一个条带的高分七号波形数据的处理得到,其相关系数和残差的平均值分别为99.75%和2.13,均小于已公布的波形处理方法得到的结果。同时,选取了三组来自于地球科学激光观测系统(Geoscience Laser Altimeter System,GLAS)的混叠原始波形,基于本文的波形处理方法提取的波形特征参数及高度反演模型,使得目标高度的反演精度分别提高0.447m、0.207m和0.390m,综合处理结果表明,WDGLM波形分解方法具有更好的普适性、精度高等特点。更多还原

【Abstract】 Spaceborne borne laser altimeter with waveform recording function is a new type of active remote sensing equipment.There is a correspondence between the received pulse echo collected by the spaceborne borne laser altimeter and the geometric characteristic parameters of the target.By processing and analyzing the received pulse echo signal,the geometric information such as the distance,height,inclination and roughness of the target can be retrieved.Therefore,spaceborne borne laser altimetry is widely used in oceanography,ecology,topography,glaciology and other fields,and the development of a universal processing algorithm to receive pulse-echo data is the key to ensure the accuracy of target information retrieval in these fields.At present,the published received waveform data processing method is mainly based on the assumption that the received echo is composed of a mixture of gaussian components.The method of inflection point and nonlinear least square fitting is used to extract waveform parameters.These methods have poor effect on waveform processing of non-gaussian components or components with obvious aliasing.This thesis mainly carried out the following aspects of the research work:(1)Based on the principle of receiving pulse echo signal by satellite-borne laser altimeter,the theoretical expression of multi-mode echo is derived.Through the simulation analysis of echo,the fitting model of echo processing is determined by using the biased normal model;(2)According to the spaceborne borne laser altimeter multimodal distribution characteristics of echo signal.This paper presents an echo data processing algorithm based on layer by layer decomposition of waveform with gradient descent(Waveform Decomposition on Gradient descent-and Levenberg Marquardt,WDGLM);(3)The WDGLM echo data processing algorithm is used to process and analyze the simulated echo data and the actually collected echo data,and the fitting residual and correlation coefficient of the echo are used as the indexes to evaluate the echo processing results.By processing the actual waveform data of a strip,the average values of correlation coefficient and residual were 99.75% and 2.13,are all smaller than the results obtained by the published waveform processing method.At the same time,three sets of aliased original waveforms from the Geoscience Laser Altimeter System are selected.Based on the waveform feature parameters extracted by the waveform processing method in this paper and the height inversion model,the inversion accuracy of the target height is improved by 0.447 m,0.207 m and 0.390 m,respectively.The results show that the WDGLM waveform decomposition method has better universality and higher precision.更多还原