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Proceedings Paper

Polarized bidirectional reflectance from leaves in the visible and infrared
Author(s): Peter N. Raven; David L. Jordan; Catherine E. Smith
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Paper Abstract

The incorporation of polarisation sensitive optics offers considerable potential for improving the utility of remote sensing imaging systems operating within the visible or infrared wavebands. Systems now exist allowing measurement of the four components of Stokes vector arising from each pixel in the image. In order to develop the interpretation of polarimetric images, knowledge is required of the polarised directional reflectance properties of the materials in the scene, which determine the radiation reaching the sensor. Natural vegetation forms a significant element of many scenes observed with remote sensing systems. Although the size of a leaf may be below the spatial resolution of a system, the reflectance properties of individual leaves will affect the polarimetric data observed. This paper will report the results of measurements of the linear polarised bidirectional reflectance distribution function (BRDF) from two examples of leaves. The polarimetric properties of the directional reflectance from an individual leaf will depend on the surface and volume scattering properties. We report data on two leaves representing extreme cases of the leaf structure. Laurel (prunus laurecatious) has a nacreous surface creating a gloss finish to the leaf. Mullein (verbascum thapsus) has a highly pubescent surface, creating a highly diffuse surface reflectance. Measurements of the linear polarisation BRDF are reported at 632.8nm, 1064nm, 3.39pm and 10.6µm as a function of the polar scatter angles. These wavelengths characterise the polarised reflectance from the leaves under different conditions of absorption and scattering. In both cases the body of the leaf acts a highly diffuse reflector through multiple scattering, but this mechanism is only important when the absorption by the leaf constituents is low. In the spectral regions of moderate and high absorption the surface reflectance dominates. In the case of laurel the surface is relatively smooth, with an associated Brewster angle, whereas the data suggests the layer of hair covering a mullein leaf acts as an array of scattering sources.

Paper Details

Date Published: 15 November 2000
PDF: 9 pages
Proc. SPIE 4133, Polarization Analysis, Measurement, and Remote Sensing III, (15 November 2000); doi: 10.1117/12.406616
Show Author Affiliations
Peter N. Raven, Defence Evaluation and Research Agency Malvern (United Kingdom)
David L. Jordan, Defence Evaluation and Research Agency Malvern (United Kingdom)
Catherine E. Smith, Defence Evaluation and Research Agency Malvern (United Kingdom)


Published in SPIE Proceedings Vol. 4133:
Polarization Analysis, Measurement, and Remote Sensing III
David B. Chenault; Walter G. Egan; Michael J. Duggin; Michael J. Duggin; Walter G. Egan; Dennis H. Goldstein, Editor(s)

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