Abstract
Optical properties of light reflected from leaves can be described by both intensity and polarization, however, most studies focused on the intensity in the estimation of plant leaf biochemical parameters. In this study, multiangular photometric and polarimetric measurements of leaves from three different plant species are first performed in laboratory to estimate leaf chlorophyll content (LCC) using spectral indices at different viewing zenith angles. Based on the Stokes parameters, the spectral indices in terms of the I parameter reflectance factors measured in laboratory (IpRFlab if polarizer extinction is considered) can be used to estimate LCC, which has a similar accuracy as bidirectional reflectance factor (BRF); and the nonpolarized spectral proportion [the reduction of bidirectional polarized reflectance factor (BPRF) from IpRF (IpRF-BPRF)] improves the ability of the spectral indices, including single wavelength, simple ratio, simple difference and normalized difference indices, along with some other indices to estimate LCC using multiangular measurements. Subsequently, the field photometric and polarimetric measurements of leaves further confirm that the nonpolarized proportion improves the estimation of LCC for some spectral indices. These results not only provide evidence that the IpRFlab and IpRFfield taken from polarimetric measurements can be considered as the proxy of photometric measurements (BRF and HDRF) in both laboratory and field but also open the possibility to improve the accuracy of LCC estimation using a nonpolarized spectral reflectance factor from multiangular polarimetric measurements. These findings indicate that polarized remote sensing may play a significant role in vegetation studies.
Highlights
L EAF pigment contents are typically used as indicators of plant physiological status and stresses and are indicative of plant productivity
We examined if the nonpolarized spectral reflectance factor can improve the estimation of leaf chlorophyll content (LCC) when using spectral indices at different viewing directions in the laboratory condition
The BPRFlab of leaves from the three different plant species [see Fig. 3(a)–(c)] is not completely independent of wavelength, because of the leaf surface refractive index as a function of the wavelength, which leads to the variation of bidirectional polarized reflectance factor (BPRF) at different wavelengths [52]
Summary
L EAF pigment contents are typically used as indicators of plant physiological status and stresses and are indicative of plant productivity. Information about the polarized component of reflected light is potentially related to leaf or vegetation surface structure properties [27], [52], [80], whereas the nonpolarized component may be useful for describing the inner components of the leaf, such as pigmentation [29], [33]. The above-mentioned studies are primarily focused on the polarized proportion of reflectance from leaf surfaces, which has direct or indirect relationships with vegetation properties [34], [35], [41]. The polarimetric measurements of leaves under different incident zenith angles were used to further confirm the effectivity of the nonpolarized reflectance factor for improving the estimation of LCC in the field condition
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
