Modeling of Leaf Anatomy and Properties (Includes PROSPECT Models and 3-D Models) Three-Dimensional Representation of Leaf Anatomy - Application of Photon Transport  Radiosity or ray tracing models have opened new prospects in the application of remote sensing to agriculture and ecology. At the leaf scale, it is now possible to track a single photon from cell to cell and to derive the optical properties of the entire blade by following the paths of million photons. As a detailed description of the three-dimensional leaf internal structure is required, the first part of this paper reviews the methods to obtain that kind of information. The second part is a sensitivity analysis of the Raytran model: the absorption profiles of two leaves with different internal structures are calculated and commented.   Jacquemoud, S., J.-P. Frangi, Y. Govaerts, and S.L. Ustin. 1997.  Three-dimensional representation of leaf anatomy - Application of photon transport,  7th Int. Symp. Physical Measurements and Signatures in Remote Sensing, April 7-11, 1997, Courchevel, France. Vol. 1, pp. 295-302.   Three-Dimensional Radiation Transfer Modeling in a Dicotyledon Leaf  The propagation of light in a typical dicotyledon leaf is investigated with a new Monte Carlo ray-tracing model. The three-dimensional internal cellular structure of the various leaf tissues, including the epidermis, the palisade parenchyma, and the spongy mesophyll, is explicitly described. The objective of this study is to investigate how the internal three-dimensional structure of the tissues and the optical properties of cell constituents control the reflectance and transmittance of the leaf Model results compare favorably with laboratory observations. The influence of the roughness of the epidermis on the reflection and absorption of light is investigated, and simulation results confirm that convex cells in the epidermis focus light on the palisade parenchyma and increase the absorption of radiation.   Govaerts, Y.M., S. Jacquemoud, M.M. Verstraete, and S. L. Ustin. 1996. Three-dimensional radiation transfer modeling in a dicotyledon leaf.  Applied Optics 35: 6585-6598.    Estimating Leaf Biochemistry Using the PROSPECT Leaf Optical Properties Model  The biophysical, biochemical, and optical properties of 63 fresh leaves and 58 dry leaves were measured to investigate the potential of remote sensing to estimate the leaf biochemistry from space. The amount of chlorophyll, water, protein, cellulose, hemicellulose, lignin, and starch was determined on these leaves using standard wet chemistry techniques. These experimental data were wed to improve the PROSPECT model, a simple but effective radiative transfer model that calculates the leaf optical properties with a limited number of input parameters: a structure parameter and the leaf biochemistry. The new model construction mainly consisted in providing specific absorption coefficients for the biochemical constituents; the comparison with absorption spectra of pure materials derived from the literature showed good agreement. In the inversion, however, it was necessary to group some leaf components in order to estimate leaf biochemistry with reasonable accuracy.  Jacquemoud, S., S.L. Ustin, J. Verdebout, G. Schmuck, G. Andreoli, and B. Hosgood.  (1996) Estimating Leaf Biochemistry Using the PROSPECT Leaf Optical Properties Model.   Remote Sensing of Environment 56(3): 194-202.   Modeling Plant Leaf Bidirectional Reflectance and Transmittance with a 3-d Ray Tracing Approach A new radiative transfer model based on Monte Carlo ray tracing techniques of leaf optical properties has been developed, where the internal three-dimensional cellular structure is explicitly described to represent morphological properties of a typical dicotyledon leaf. The main objective of this work is to perform sensitivity analyses at different wavelengths to test the influence of the leaf internal structure as well as that of pigment and water concentrations on the light attenuation profile and the bidirectional scattering shape. (PDF File) Govaerts, Y. M., S. Jacquemoud, M. M. Verstraete, and S. L. Ustin. (1995). ìModeling Plant Leaf Bidirectional Reflectance and Transmittance with a 3-d Ray Tracing Approach.î IGARSS 95: Proceedings International Geoscience and Remote Sensing Symposium, Greenbelt, MD, February 27-March 1, 1995.   Modeling Leaf Optical Properties Using a Radiative Transfer Model. (PDF File)  GOAL: to simulate the leaf spectral reflectance and transmittance as a function of the leaf biophysical characteristics.   Jacquemoud S., S.L. Ustin, J. Verdebout, G. Schmuck, G. Andreoli, B. Hosgood. (1995), Modeling Leaf Optical Properties Using a Radiative Transfer Model, (PDF File) NASA Remote Sensing Science Workshop, Greenbelt (MD), 27 February - 1 March 1995. poster.   PROSPECT Redux  Jacquemoud, S., S.L. Ustin, J. Verdebout, G. Schmuck, G. Andreoli, and B. Hosgood.  (1995) Prospect Redux.  In Summaries of the Fifth Annual JPL Airborne Earth Science Workshop.  Jet Propulsion Laboratory, Pasadena, CA.  January 23-26, 1995. Vol. 95-1, p.99-104.   Relationships Between Pigment Composition Variation and Reflectance for Plant Species from a Coastal Savannah in California  Advances in imaging spectroscopy have indicated that remotely sensed reflectance measurements of the plant canopy may be used to identify and quantify some classes of canopy biochemicals.  To examine the relationship between biochemical concentration and leaf reflectance signal, our strategy has been to sample a variety of naturally occurring species to measure leaf reflectance and pigment compositions. We hope to extend our understanding of pigment reflectance effects to interpret small overlapping absorbances of other biochemicals in the infrared region.  In parallel, we have modified the PROSPECT leaf reflectance model to test the contributions of pigments or pigment group concentrations.  Our modifications include breaking out the pigment concentration parameter into separate components for chlorophyll a and b and a number of xanthophylls and carotenes, and introducing a shift and convolution function to model the spread and shift from their in vitro measurements to their in vivo state. Further we have considered how the matrix elements vary with species.   Ustin, S. L., E. W. Sanderson, Y. Grossman, Q. J. Hart, and R. S. Haxo. (1993). Relationships Between Pigment Composition Variation and Reflectance for Plant Species from a Coastal Savannah in California. Summaries of the Fourth Annual JPL Airborne Earth Science Workshop: AVIRIS Workshop, Washington, D. C., 93, 181-184.