Abstract Topography is one of the key factors that impact remotely sensed data and their interpretation. Indeed, combined with the viewing geometry and neighbour effects, it strongly affects the direct, diffuse and multi-scattered scene irradiance, which in turn impacts the radiative budget and remote sensing signals of the landscapes. The increased availability of digital elevation models (DEM) and the advancement of 3D radiative transfer (RT) models allow us to better address these topographic effects. DART (Discrete Anisotropic Radiative Transfer) is one of the most accurate and comprehensive 3D RT models that simulate remote sensing observations of natural and urban landscapes with topography and atmosphere. It simulates environmental effects (i.e., impact of adjacent landscape on the observed landscape) using a so-called infinite slope mode that infinitely duplicates the observed landscape while ensuring the continuity of slope and altitude at the DEM edges. Up to DART version 5.7.4, this mode was slightly inaccurate and computer intensive, depending on the topography. This paper presents an innovative modelling strategy that greatly improves it in terms of accuracy, image quality and computer efficiency. For that, a fictive auxiliary oblique plane, adapted to the landscape topography, is introduced for managing the scene illumination, the Earth-Atmosphere coupling and the storage of the radiation that exits the scene before being projected onto the sensor plane. Improvements and validations are illustrated both visually and quantitatively by DART images, radiometric products and radiative budget. For example, the observed reflectance of a Lambertian slope is equal to the expected analytical value. In addition, the solar plane reflectance of a forest on a mountain slope (experimental scene) has an average error of about 0.01% relative to the reflectance of the same forest stand in the reference scene (i.e., nine duplications of the experimental scene). This new modelling is already integrated in the official DART version ( https://dart.omp.eu ).

中文翻译：

---

倾斜景观的 DART 辐射传输建模

摘要 地形是影响遥感数据及其解释的关键因素之一。事实上，结合观察几何和邻居效应，它强烈影响直接、漫射和多散射场景辐照度，进而影响景观的辐射收支和遥感信号。数字高程模型 (DEM) 的可用性增加和 3D 辐射传输 (RT) 模型的进步使我们能够更好地解决这些地形影响。DART（离散各向异性辐射传输）是最准确、最全面的 3D RT 模型之一，可模拟对自然和城市景观的地形和大气的遥感观测。它模拟环境影响（即，相邻景观对观察景观的影响）使用所谓的无限坡度模式，无限复制观察到的景观，同时确保 DEM 边缘坡度和高度的连续性。在 DART 版本 5.7.4 之前，此模式略微不准确且计算机密集，具体取决于地形。本文提出了一种创新的建模策略，在准确性、图像质量和计算机效率方面大大提高了它。为此，引入了一个适用于景观地形的虚构辅助斜面，用于管理场景照明、地球-大气耦合以及在投射到传感器平面之前离开场景的辐射的存储。改进和验证通过 DART 图像直观和定量地说明，辐射产品和辐射预算。例如，观察到的朗伯斜率反射率等于预期的分析值。此外，山坡上的森林（实验场景）的太阳平面反射率相对于参考场景（即实验场景的九个重复）中同一林分的反射率的平均误差约为0.01%。这种新建模已集成到官方 DART 版本 (https://dart.omp.eu) 中。实验场景的九个重复）。这种新建模已集成到官方 DART 版本 (https://dart.omp.eu) 中。实验场景的九个重复）。这种新建模已集成到官方 DART 版本 (https://dart.omp.eu) 中。