ABSTRACT

Optical remote sensing allows to efficiently monitor forest ecosystems at regional and global scales. However, most of the widely used optical forward models and backward estimation methods are only suitable for forest canopies in flat areas. To evaluate the recent progress in forest remote sensing over complex terrain, a satellite-airborne-ground synchronous Fine scale Optical Remote sensing Experiment of mixed Stand over complex Terrain (FOREST) was conducted over a 1 km×1 km key experiment area (KEA) located in the Genhe Reserve Areain 2016. Twenty 30 m×30 m elementary sampling units (ESUs) were established to represent the spatiotemporal variations of the KEA. Structural and spectral parameters were simultaneously measured for each ESU. As a case study, we first built two 3D scenes of the KEA with individual-tree and voxel-based approaches, and then simulated the canopy reflectance using the LargE-Scale remote sensing data and image Simulation framework over heterogeneous 3D scenes (LESS). The correlation coefficient between the LESS-simulated reflectance and the airborne-measured reflectance reaches 0.68–0.73 in the red band and 0.56–0.59 in the near-infrared band, indicating a good quality of the experiment dataset. More validation studies of the related forward models and retrieval methods will be done.

摘要

光学遥感可以有效地监测区域和全球范围内的森林生态系统。然而，大多数广泛使用的光学前向模型和后向估计方法仅适用于平坦地区的森林冠层。为了评估复杂地形森林遥感的最新进展，在1 km×1 km关键实验区（KEA）上进行了混合站立复杂地形（FOREST）的星-机-地同步精细尺度光学遥感实验（FOREST） 2016 年位于根河保护区。建立了 20 个 30 m×30 m 基本采样单元 (ESU) 来代表 KEA 的时空变化。同时测量每个 ESU 的结构和光谱参数。作为案例研究，我们首先使用基于个体树和体素的方法构建了 KEA 的两个 3D 场景，然后在异构 3D 场景 (LESS) 上使用 LargE-Scale 遥感数据和图像模拟框架模拟冠层反射率。LESS模拟反射率与机载测量反射率之间的相关系数在红波段达到0.68-0.73，在近红外波段达到0.56-0.59，表明实验数据集质量良好。将对相关的前向模型和检索方法进行更多的验证研究。