一种基于重复轨道高程数据的坡度估计算法
)An Algorithm for Slope Estimation from Repeat Tracks of ICESat/GLAS
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摘要: 目的 根据ICESat/GLAS重复轨道高程数据,提出了地形坡度计算模型和算法。算法的关键步骤是在多个重复轨道中选出参考重复轨道(RT)和比较重复轨道(CT),并找到参考重复轨道上的参考起始脚点(RSF)和比较重复轨道上的比较起始脚点(CSF)。利用ICESat卫星在2003～2009年经过北京地区的地面轨道420时获得的数据进行实验,计算得到不同重复轨道的坡度估计值的差值,以及坡度差值的均方根和标准方差。结果显示,不同轨道间得出的坡度差值的均方根和标准方差会随着该轨道与参考轨道之间距离变化率的增大而增大。将坡度计算结果绘制在北京地图上,并且与图像地图进行对比,可以看出二者结果的一致性。将计算结果和基于SRTM高程数据的坡度进行了对比,验证了本文结果的可靠性。Abstract: Objective A slope estimation model and algorithms were advanced based on the repeat ground track el-evation data collected from the Geoscience Laser Altimeter System(GLAS)on board the Ice,Cloudand land Elevation Satellite(ICESat).Innovative algorithm steps show and confirm the referencestarting point(RSF)on the reference track(RT)and the corresponding starting point(CSF)on otherrepeat corresponding track(CT).The slope model and algorithms were validated with the elevationdata from ground track 420collected by ICESat/GLAS when passing over the Beijing area during2003-2009.The RMS and standard deviation of slope differences between RT and CTs were deducedand discussed.The results show that the RMS and standard deviation(STD)of the slope differencesincrease with the increase in the STD/RMS of the separation between the CT and RT.The slopedrawing on a geographic map were coincidental with the geographical ground truth when comparedwith an image obtained from Google map.The calculated slope based on ICESat/GLAS data was com-pared to that based on SRTM DEM data demonstrating the reliability of these results.
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