地形对大光斑激光雷达森林回波影响研究  

Effects of Terrain on the Large Footprint Lidar Waveform of Forests

作　　者：庞勇[1] 李增元[1] Sun Guoqing Michael Lefsky 车学俭[1] 陈尔学[1] 

机构地区：[1]中国林业科学研究院资源信息研究所,北京100091 [2]马里兰大学地理系,马里兰20742,美国 [3]科罗拉多州立大学森林、草地与流域系,科罗拉多80523,美国

出　　处：《林业科学研究》2007年第4期464-468,共5页Forest Research

基　　金：国家自然科学基金项目(30230420);(40601070);国家863计划课题(2002AA133050);中国林业科学研究院基金项目(2004Z04)支持

摘　　要：利用三维激光雷达森林回波波形模型模拟了地形对波形的影响,并用ICEsat GLAS的数据对模拟结果进行了验证。结果表明坡度对大光斑激光雷达波形影响较大,随着坡度的增大,地面回波和树冠回波都展宽,波形长度也随之增加,同时地面的波峰和植被的波峰值都降低,来自地面的回波明显减少,并逐渐与靠近地面的回波发生信息混叠。鉴于二者的关系呈近似线性正相关,在实际的森林参数反演中可望通过减去一个含有坡度或地形起伏度的因子进行地形效应纠正。The large footprint lidar has demonstrated its great potential for accurate estimation of many forest parameters. As the lidar waveform is a record of return signal as a function of time from sensor to target, the terrain within lidar footprint will affect the waveform through changing the distance of target to sensor and make effective footprint area larger. This paper simulated the effects of terrain on large footprint lidar waveform using a three dimensional lidar waveform model from forest. The analysis of ICEsat GLAS laser2b data of Northeast China showed the same phenomena with simulated results. The results showed that both of the ground return signals and vegetation return signals were widened and the peak decreased with slope increasing. The return singles began earlier with slope increasing. Meanwhile, the slope angle from the signal beginning to first peak of the waveform decreased. These two phenomena caused the error in detecting signal beginning and the following forest height estimation. The recorded lidar waveform would contain false vegetation peak at certain slope level. The relationship between waveform length and terrain slope was near linear. So the effects of terrain on lidar wavefrom could be corrected by subtracting a factor of slope or terrain index.

关 键 词：地形 大光斑激光雷达 森林回波波形 ICESAT GLAS 

分 类 号：TP701[自动化与计算机技术—检测技术与自动化装置]