ABSTRACT

The Gao Fen-7 (GF-7) satellite employs a laser altimeter to provide the global measurement of ground elevation. This study aimed to evaluate the performance of GF-7 laser altimeter data in ground elevation retrieval over vegetated areas. First, GF-7 waveforms were processed to obtain the ground elevation. Second, we verified the ground elevation accuracy using airborne light detection and ranging (LiDAR) data. Finally, we analysed the influence of various factors (e.g., slope, signal-to-noise ratio (SNR), vegetation height) on ground elevation estimation. Results showed that the lowest Gaussian peak best represents the ground elevation, with root mean squared error (RMSE) and mean error of 2.30 m and 0.28 m, respectively. The laser 1 performs better than laser 2 in ground elevation retrieval as indicated by the lower RMSE. The ground elevation accuracy differed significantly across various land cover types and showed a pattern of lower estimation accuracy with more complex vertical structure. Additionally, results also indicated that the ground elevation accuracy decreased with increasing slope, vegetation height and vegetation coverage but increased with increasing SNR. Overall, our study found that GF-7 laser altimeter data have a strong capability to retrieve the ground elevation over vegetated areas.

摘要

高分七号（GF-7）卫星采用激光高度计来提供地面高程的全球测量。本研究旨在评估 GF-7 激光高度计数据在植被区域地面高程反演中的性能。首先，对GF-7波形进行处理以获得地面高程。其次，我们使用机载光探测和测距 (LiDAR) 数据验证了地面高程精度。最后，我们分析了各种因素（如坡度、信噪比（SNR）、植被高度）对地面高程估计的影响。结果表明，最低高斯峰最能代表地面高程，均方根误差（RMSE）和平均误差分别为2.30 m和0.28 m。如较低的 RMSE 所示，激光器 1 在地面高程检索中的性能优于激光器 2。不同土地覆盖类型的地面高程精度存在显着差异，并显示出估算精度较低且垂直结构更复杂的模式。此外，结果还表明，地面高程精度随着坡度、植被高度和植被覆盖度的增加而降低，但随着信噪比的增加而增加。总体而言，我们的研究发现 GF-7 激光高度计数据具有强大的恢复植被区域地面高程的能力。