The effect of specular reflectance on the relationship between reflectance and vegetation amount

Abstract The specular reflectance of a leaf is unrelated to wavelength or leaf content. However, a vegetation canopy is not a large leaf and specular reflectance is likely to be related to wavelength and vegetation amount because of the correlation between canopy geometry and vegetation amount. It was hypothesised that if the specular component were removed from the total (specular and diffuse) reflectance of a canopy then the strength of the correlation between diffuse reflectance and vegetation amount would decrease in near-infrared wavelengths and increase in visible wavelengths. Field based measurements of grassland using a polarising radiometer verified this hypothesis. It was recommended that where possible the specular component of the total reflectance be determined, at least in visible wavelengths, prior to the estimation of vegetation amount.

[1]  Kinsell L. Coulson,et al.  Polarization and Intensity of Light in the Atmosphere , 1989 .

[2]  P. J. Curran,et al.  Radiometric leaf area index , 1988 .

[3]  L. D. Miller,et al.  SHORTGRASS PRAIRIE SPECTRAL MEASUREMENTS , 1975 .

[4]  P. J. Curran,et al.  Remote sensing using partially polarized light , 1986 .

[5]  Edward J. Milton,et al.  Principles of field spectroscopy , 1987 .

[6]  Kiyoshi Tsuchiya,et al.  An analysis on Polarization Characteristics of Leaf and Vegetation , 1989 .

[7]  E. Schanda,et al.  Physical Fundamentals of Remote Sensing , 1986 .

[8]  B F Robinson,et al.  Specular, diffuse, and polarized light scattered by two wheat canopies. , 1985, Applied optics.

[9]  Vern C. Vanderbilt,et al.  Polarized and non-polarized leaf reflectances of Coleus blumei , 1987 .

[10]  Kinsell L. Coulson,et al.  Effects of reflection properties of natural surfaces in aerial reconnaissance. , 1966, Applied optics.

[11]  Susan L. Ustin,et al.  Polarization of Light by Vegetation , 1991 .

[12]  B. Holben,et al.  Leaf water stress detection utilizing thematic mapper bands 3, 4 and 5 in soybean plants , 1983 .

[13]  Bruce W. Fitch,et al.  Polarization of light reflected from grain crops during the heading growth stage , 1984 .

[14]  L. Grant,et al.  Polarization of light scattered by vegetation , 1985, Proceedings of the IEEE.

[15]  Vern C. Vanderbilt,et al.  Variations in the polarized leaf reflectance of Sorghum Bicolor , 1987 .

[16]  Vern C. Vanderbilt,et al.  Specular, diffuse, and polarized imagery of an oat canopy , 1988 .

[17]  P. J. Curran,et al.  Airborne MSS data to estimate GLAI , 1987 .

[18]  P. Curran.  Multispectral remote sensing of vegetation amount , 1980 .

[19]  E. Milton.  On the suitability of Kodak neutral test cards as reflectance standards , 1989 .

[20]  G. Guyot,et al.  POLARISATION DE LA LUMIÈRE PAR LES COUVERTS VÉGÉTAUX: POSSIBILITÉS D'APPLICATIONS AGRONOMIQUES , 1990 .

[21]  Walter G. Egan,et al.  Photometry and polarization in remote sensing , 1985 .

[22]  Maurice Herman,et al.  Polarization of light reflected by crop canopies , 1991 .

[23]  Paul N. Woessner,et al.  Polarization of light scattered by clover , 1987 .

[24]  C. Tucker.  Asymptotic nature of grass canopy spectral reflectance. , 1977, Applied optics.

[25]  Paul J. Curran,et al.  The relationship between polarized visible light and vegetation amount , 1981 .

[26]  L. Grant.  Diffuse and specular characteristics of leaf reflectance , 1987 .

[27]  Tsuyoshi Matsui,et al.  Digital image processing in polarized light for evaluation of foliar injury , 1982 .