ICESat/GLAS测高精度与回波波形关联性分析

Analysis of Correlation between ICESat/GLAS Measurement Accuracy and Echo Waveform

为了全面了解线性体制星载激光测高仪测高精度与地物、地形的关系,本文以机载点云数据为参考数据,选取美国部分区域为试验区,采用构建不规则三角网内插的方法,分析了GLAS激光测高仪数据在不同坡度坡向、不同地物以及升轨降轨的测高精度,并探讨了GLAS测高精度与激光回波波形的关系。实验结果表明:在波形展宽较小、坡度平缓的地区,GLAS激光点的高差中误差为0.7185 m;在波形展宽较大、坡度陡峭的地区,中误差为6.5321 m。针对波形较为理想的农地,湖泊两类地物的高差中误差分别为0.6247 m、1.5786 m,针对波形变形严重,回波波峰不明显的沙漠、林地地区的高差中误差分别为2.0551 m和7.1369 m。在平坦地区,当采用升轨测量模式时激光点高差中误差为0.6183 m;而降轨测量的高差中误差为0.8492 m。总体而言,不同坡向条件下,GLAS激光点的测高值要高于实际地面高程。

In order to fully understand the relationship between accuracy of linear system space-borne laser altimeter and terrain,this paper takes airborne point cloud data as reference data,selects some regions of the United States as test areas,and uses the method of constructing Triangulated Irregular Network to analyze the elevation accuracy of GLAS laser altimeter data in different slope、slope aspect、different terrain objects and different models,and discusses the relationship between measuring precision and laser echo waveform.The experimental results show that,in areas with small waveform broadening and gentle slope,the elevation error of GLAS laser point is 0.7185 m;in areas with large waveform broadening and steep slope,the elevation error is 6.5321 m.In areas with ideal waveforms,the error of farmland and lake are respectively 0.6247 m and 1.5786 m,In areas where the waveform is seriously deformed and the echo peak is not obvious,the elevation error of desert and forest are respectively 2.0551 m and 7.1369 m.In flat terrain,the elevation error of laser point is 0.6183 m when using the ascend track mode,while the elevation error of descend track is 0.8492 m.Generally speaking,under different slope aspect conditions,the elevation of GLAS laser point is higher than the actual ground elevation.