arXiv subjects

Sophie Royer

Publications and source records attributed to Sophie Royer.

3 recordsLinked to original sources

arXiv2005

TTRG integration of light transport equations: Azymuthally integrated radiances inside a Lambertian foliage

A method for numerically integrating transport equations, combining transfer matrices, transmission-reflection matrices, and Green's matrices (TTRG), was recently proposed. The present paper deals specifically with azymuthally integrated radiances inside a horizontally homogeneous canopy of Lambertian leaves. Its main purpose is to test the accuracy of TTRG by applying it to non-trivial models possessing analytical solutions, that were given in another paper. Comparison is made with the widely used iterative integration (or 'relaxation' method). Cases of extreme light trapping are given for which iterative integration is hardly practical, while TTRG remains as accurate and rapid.

physics.comp-ph↗

arXiv2005

Light propagation in a horizontally homogeneous Lambertian foliage: Analytically solvable models

Various numerical methods exist for obtaining the radiances inside a canopy of leaves above a partly reflecting ground. In view of testing the accuracy of these diverse methods, it is desirable to have at one's disposal non-trivial models possessing analytical solutions, against which to compare numerical reuslts. Such models are obtained in the present paper, for the case of a horizontally homogeneous foliage of Lambertian leaves, modeled as a turbid medium. Our treatment is more general than usual in that we allow the top and under sides of leaves to have different optical coefficients. Besides being more realistic, this enables artificial situations, such as extreme light trapping, testing the limits of various numerical methods.

physics.comp-ph↗

arXiv2005

Integrating transport equations by combining transfer matrices, transmission-reflection matrices, and Green's matrices, in the context of light propagation in foliage

In many problems, it is necessary to integrate a transport equation. Here we consider specifically light incident on a horizontally homogeneous foliage ('the canopy'), modeled as a turbid medium. This is often treated by integrating numerically the light transport equation, assuming initial values for the reflected radiances, and iterating until the radiances stabilize. We here present a method combining transfer matrices, transmission-reflection matrices, and Green's matrices (TTRG). This method is both fast and accurate, especially if one must do many computations on the same canopy, for different incident fluxes and internal emissions. There exist (artificial) extreme light trapping situations for which iterative integration is hardly practical, while TTRG remains as efficient.

physics.comp-ph↗