基于ICESat-GLAS全波形数据的坡地森林冠层高度估测

Study on Estimation of Forest Canopy Height over Sloping Terrain Based on ICESat-GLAS Full Waveform Data

地形坡度对星载LiDAR的回波波形会产生很大的影响,并会进一步影响森林结构参数的正确估测。比较两类参数量化地形坡度的能力:辅助地形DEM数据的地形指数和波形自身参数后缘长度,以在反演坡地森林冠层高度时仅从回波波形本身出发,而不需要借助于其他辅助数据。采用估测坡地森林冠层高度的两组对比模型来比较:第1组对比模型是Xing模型和基于未改进的后缘长度的线性模型;第2组对比模型是Xing模型和基于改进的后缘长度的线性模型。结果表明,在两组对比模型中,基于波形自身特征参数的模型结果均优于基于辅助地形DEM数据的地形指数的Xing模型,说明在量化地形坡度时,波形的自身特征参数的量化能力要高于辅助地形DEM数据的量化能力。

The terrain slope will exert a huge impact on spaceborne LiDAR return waveform and further affect the correct estimation of forest structure parameters. This study compared the capability of two types of parameters to quantify the terrain slope ： terrain index derived from the auxiliary terrain DEM data and trailing edge extent derived from waveform＇ s own parameters, just starting from return waveform when forest canopy height over sloping area was inversed without the need of other auxiliary data. In this study, forest canopy height over sloping area was estimated with two groups of contrast model to compare the capability of terrain index and trailing edge extent to characterize terrain slope ： the first contrast group is Xing model and linear model based on unmodified trailing edge extent; the other contrast group is Xing model and linear model based on modified trailing edge extent. Results indicated that in these two groups of contrast models for estimating forest canopy height over sloping area, model estimation result based on waveform itself characteristic parameters is better than estimation result based on Xing model derived from the auxiliary terrain DEM data. Therefore, the capability of waveform＇ s own characteristic parameters is higher than that of auxiliary terrain DEM data for quantifying terrain slope.