Abstract
Three-dimensional (3D) radiative transfer models are the most accurate remote sensing models. However, presently the application of 3D models to heterogeneous Earth scenes is a computationally intensive task. A common approach to reduce computation time is abstracting the landscape elements into simpler geometries (e.g., ellipsoid), which, however, may introduce biases. Here, a hybrid scene structuring approach is proposed to accelerate the radiative transfer simulations while keeping the scene as realistic as possible. In a first step, a 3D description of the Earth landscape with equal-sized voxels is optimized to keep only non-empty voxels (i.e., voxels that contain triangles) and managed using a bounding volume hierarchy (BVH). For any voxel that contains triangles, within-voxel BVHs are created to accelerate the ray–triangle intersection tests. The hybrid scheme is implemented in the Discrete Anisotropic Radiative Transfer (DART) model by integrating the Embree ray-tracing kernels developed at Intel. In this paper, the performance of the hybrid algorithm is compared with the original uniform grid approach implemented in DART for a 3D city scene and a forest scene. Results show that the removal of empty voxels can accelerate urban simulation by 1.4×~3.7×, and that the within-voxel BVH can accelerate forest simulations by up to 258.5×.
Highlights
Understanding and modeling the radiative behavior at Earth’s surface is essential for a wide range of scientific domains including agriculture, forestry and urban microclimate
We present a hybrid scene structuring scheme that is designed to accelerate the radiative transfer modeling in the Discrete Anisotropic Radiative Transfer (DART) model, because the latter one simulates the radiative budget and remote sensing images of Earth landscapes using the uniform grid
DART can work on scenes that are simulated with any combinations of triangles and fluids, including the so-called turbid medium that is often used for giving a statistical representation of vegetation
Summary
Understanding and modeling the radiative behavior at Earth’s surface is essential for a wide range of scientific domains including agriculture, forestry and urban microclimate. We present a hybrid scene structuring scheme that is designed to accelerate the radiative transfer modeling in the Discrete Anisotropic Radiative Transfer (DART) model, because the latter one simulates the radiative budget and remote sensing images of Earth landscapes using the uniform grid. DART is one of the most comprehensive physical-based models [6] It can simulate the 3D radiative transfer budget and various remote sensing acquisitions (e.g., LiDAR, spectroradiometer and solar-induced fluorescence, etc.) over the whole optical domain, including atmosphere. DART can work on scenes that are simulated with any combinations of triangles and fluids, including the so-called turbid medium that is often used for giving a statistical representation of vegetation This newly designed structuring scheme combines the advantages of uniform grid and BVH, which enables DART to simulate larger scenes under higher spatial resolutions with lower computational cost.
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