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Proceedings Paper

Modeling radiative transfer in heterogeneous 3D vegetation canopies
Author(s): J. P. Gastellu-Etchegorry; V. Demarez; Veronique Pinel; Francis Zagolski
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Paper Abstract

The DART (discrete anisotropic radiative transfer) model simulates radiative transfer in heterogeneous 3-D scenes; here, a forest plantation. Similarly to Kimes model, the scene is divided into a rectangular cell matrix, i.e., a building block for simulating larger scenes. Cells are parallelipipedic. The scene encompasses different landscape features (i.e., trees with leaves and trunks, grass, water, and soil) with specific optical (reflectance, transmittance) and structural (LAI, LAD) characteristics. Radiation directions are subdivided into contiguous sectors with possibly uneven spacing. Topography, hot spot, and multiple interactions (scattering, attenuation) within cells are modeled. Two major steps are distinguished: (1) Illumination of cells by direct sun radiation. Actual locations of within cell scattering are determined for optimizing scattering computation. (2) Interception and scattering of previously scattered radiation. Diffuse atmospheric radiation is input at this level. Multiple scattering is represented with a spherical harmonic decomposition, for reducing data volume. The model iterates on step 2 for all cells, and stops with the energetic equilibrium. This model predicts the bi-directional reflectance factors of 3D canopies, with each scene component contribution; it was successfully tested with homogeneous covers. It gives also the radiation regime with canopies, and consequently some information about volume distribution of photosynthesis rates and primary production.

Paper Details

Date Published: 31 January 1995
PDF: 12 pages
Proc. SPIE 2314, Multispectral and Microwave Sensing of Forestry, Hydrology, and Natural Resources, (31 January 1995); doi: 10.1117/12.200743
Show Author Affiliations
J. P. Gastellu-Etchegorry, Ctr. d'Etude Spatiale des Rayonnements (France)
V. Demarez, Ctr. d'Etude Spatiale des Rayonnements (France)
Veronique Pinel, Ctr. d'Etude Spatiale des Rayonnements (France)
Francis Zagolski, Ctr. d'Etude Spatiale des Rayonnements (France)

Published in SPIE Proceedings Vol. 2314:
Multispectral and Microwave Sensing of Forestry, Hydrology, and Natural Resources
Eric Mougin; K. Jon Ranson; James Alan Smith, Editor(s)

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