基于植被表面的激光测高仪回波波形模型化分析

Modeling Raw Signals of Laser Altimeter Echo Waveform Based on Canopy Surface

针对激光测高仪中发射的激光脉冲并不是高斯对称的,并且由于目标物的影响,使用一系列标准高斯函数的和来拟合回波脉冲并不精确,本文提出改变回波分解的取模模型,通过正确模型的选取来改善回波位置的精确度。该方法采用比高斯函数复杂的对数正态函数和广义高斯函数,采用LM非线性拟合算法拟合回波波形。实验结果表明,通过对植被等回波数据的拟合显示出针对不同的地形存在不同的改善效果,同时新参数的引入可获得波形的额外信息,使得对目标物表面几何形状、反射率和粗糙度等信息的解算变得更为容易。

It has been demonstrated that decomposing the return waveforms into a mixture of Gaussian components was suitable to achieve the information of the target.But the laser impulse is slightly asymmetric,and approximating the waveforms by using a sum of Gaussians may not be an accurate representation depending on the application and target.This paper focus on the improvement of raw signal modeling and refine peak detection greatly increased the number of detected targets as well as their positional accuracy.More complex models than the Gaussian model,such as the Lognormal or generalized Gaussian functions,were introduced and fitted with backscatter waveform of canopy to improve the raw signal by LM algorithm.The results show,through introduction of new echo parameters,it is easy to extract the additional information on the target shape,and calculate reflectivity and roughness.