Polarized directional reflectance from laurel and mullein leaves

Abstract

The ability to perform polarimetric imaging throughout the visible and infrared (IR) wavebands has improved considerably in the past decade. Systems now exist that enable measurements to be made of all four Stokes parameters arising from each pixel in the image. The question of whether polarimetric imaging offers an advantage over conventional imaging methods for discrimination of plant type in scenes of natural vegetation remains to be answered. Although the size of a leaf may be below the spatial resolution of an imaging system, the polarimetric properties of individual leaves may affect the data observed from a tree or forest canopy. We report the results of measurements of the polarized hemispherical directional reflectance (HDR), which is related to the directional emissivity, and bidirectional reflectance distribution function (BRDF) from two examples of leaves. To completely characterize the polarimetric properties of a leaf, and ultimately a leaf canopy, an extensive measurement of the polarized BRDF and HDR of individual leaves is required. This is necessary because of the large range of possible relative orientations of the illumination, leaf and observer, and the range of polarization states of incident radiation. We report a limited set of laboratory measurements designed to investigate whether any gross polarimetric difference exist between two dissimilar types of plant leaves in the visible, near IR (NIR), and IR spectral wavebands. Laurel (prunus laurecatious) has a wax surface creating a gloss or glabrous appearance to the leaf. The surface of mullein (verbascum thapsus) is highly pubescent with a dense layer of hair over the adaxial surface, creating a highly diffuse surface reflectance. Significant differences are found between the two species of leaf in the measured polarized directional reflectance and emissivity.

Approach trajectory and solar position affect host plant attractiveness to the small white butterfly

“…3, S6, S7) for all color bands, with the strongest polarization at twice the Brewster's angle (53-60°). These data are consistent with both theoretical predictions and other experimental measurements of the effect of viewing angles on DoLP (Horváth et al, 2002;Raven, 2002;Rondeaux & Herman, 1991;Woolley, 1971). However, the phenomenon of lowering the DoLP with increasing ψ had not previously been noted and emerges here through whole-plant measurements incorporating multiple leaf surfaces.…”

“…Our study confirms earlier work demonstrating large differences in DoLP among plant species Grant et al, 1993) and refines our understanding of polarized reflections from plant foliage. Unlike previous studies that examined polarized reflections of single leaves, models of leaves, or plant canopies (Grant et al, 1993;Hegedüs & Horváth, 2004;Horváth et al, 2002;Horváth & Hegedüs, 2014;Maignan et al, 2009;Raven, 2002;Rondeaux & Herman, 1991;Vanderbilt & Grant, 1985;Woolley, 1971), we recorded reflections from entire plants thereby revealing several emergent phenomena. Most importantly, our modeling suggests that certain approach trajectories are optimal for foraging insects to discriminate among plant species based on the DoLP of foliar reflections.…”

Remote sensing of life: polarimetric signatures of photosynthetic pigments as sensitive biomarkers

“…Studies of optical properties of various leaves and inorganic samples have been conducted for several decades (e.g. Pospergelis, 1969, Grant et al 1993; Brakke 1994; Jacquemoud & Ustin 2001; Raven et al 2002; Suomalainen et al 2009; Peltoniemi et al . 2009).…”

“…Studies of optical properties of various leaves and inorganic samples have been conducted for several decades (e.g. Pospergelis, 1969, Grant et al 1993Brakke 1994;Jacquemoud & Ustin 2001;Raven et al 2002;Suomalainen et al 2009;Peltoniemi et al 2009). The POLDER satellite provided narrowband measurements of various landscape features which were used for agricultural or ecological studies (e.g.…”

Nondestructive diagnostics of soluble sugar, total nitrogen and their ratio of tomato leaves in greenhouse by polarized spectra–hyperspectral data fusion

“…Since the 1970s, technologies for polarization reflection spectroscopy have rapidly developed, with applications in many research areas [27] . Polarized reflectance spectroscopy was applied in a variety of plants both at the single-leaf and canopy level, such as laurel (Laurus nobilis), mullein (Verbascum thapsus L.) [28] , wheat (Triticum aestivum) [29] , chrysina gloriosa (Gloriosa superba L.) [30] , arabidopsis (arabidopsis thaliana Linn. Heynh.)…”