Multispectral polarimetric bidirectional reflectance research of plant canopy

Vegetation monitoring has been widely applied in various fields such as forest coverage and vegetation growth status. By measuring and analyzing the polarization of plant canopies, it is possible to infer the growth status of plants, thereby assessing their growth rate and providing effective technical means for areas such as crop yield estimation and ecological environment monitoring. To investigate the relationship between the properties of plant canopies and their polarization, a multispectral polarized light imaging system was constructed based on the BRDF (Bidirectional Reflectance Distribution Function) device. Through experiments and analysis on Christmas blue cabbage and hibiscus, the polarization characteristics of sparse and dense vegetation were detected. The results indicate that the polarization of denser vegetation canopies is significantly greater than that of sparser vegetation, with polarization degrees reaching 0.29 and 0.43 in the red waveband, exceeding the polarization in the blue and green wavebands. This advantage surpasses the influence of leaf roughness on polarization. Furthermore, a pBRDF model of plant canopies was established, and fitted images of polarization degree variation with zenith angle were obtained. Data inversion was conducted on the canopies of Christmas blue cabbage and hibiscus, resulting in root mean square errors of 2.3% and 1.1%, respectively.