A Continuous Wavelet Transform Based Method for Ground Elevation Estimation Over Mountainous Vegetated Areas Using Satellite Laser Altimetry

Abstract

Although a satellite laser altimetry Geoscience Laser Altimeter System (GLAS) can directly measure ground elevation, the measurement accuracy of ground elevation is generally limited over mountainous vegetated areas. Currently, most methods for ground elevation estimations that use GLAS data fail to obtain an accurate ground elevation in sloped areas. Therefore, this study aimed to propose a continuous wavelet transform (CWT) based method for better estimating ground elevation from GLAS data over mountainous vegetated areas. First, the CWT was applied to each GLAS waveform for peak detection. Second, all potential ground peaks were correctly identified using GLAS waveform parameters in conjunction with auxiliary digital elevation model data. Third, the true ground peak was determined from CWT results according to several strict rules, and then the ground elevation was calculated based on the position of the true ground peak. Finally, these ground elevation estimates were validated by the digital terrain model derived from airborne discrete-return LiDAR data in Genhe in the Neimeng province of China. Additionally, the CWT-based method was also compared with previous methods, which estimate ground elevation from GLAS data over mountainous vegetated areas based on a Gaussian decomposition. It was found that our CWT-based method can reduce the root-mean-square error of ground elevation estimates by up to 0.8 m. Overall, this study can provide an available solution for estimating ground elevation from large-footprint waveform LiDAR data over mountainous vegetated areas.