Publications

Jiao, QJ; Zhang, B; Huang, WJ; Ye, HC; Zhang, ZM; Qian, BX; Hu, BH; Wang, SL (2023). The Potential of Hue Angle Calculated Based on Multispectral Reflectance for Leaf Chlorophyll Content Estimation. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 61, 4408616.

Abstract
Remote sensing of leaf chlorophyll content (LCC) is critical in precision agriculture, forest monitoring, and pest management. Chlorophyll absorbs light in the visible and red-edge spectrum areas. However, many multispectral sensors lack red edge bands. Subsequently, the development of effective visible chlorophyll-related indicators is important. The hue angle defined in the CIE xy chromaticity diagram, which reflects the human eye's color discrimination ability relying on visible light (400- 700 nm), is introduced in this study for LCC estimation. This study proposes a new multispectral hue angle calculation method employing D65 standard illuminant data, investigates the effect of illuminant factors and band settings on hue angle calculation, and presents tristimulus weight coefficients for calculating MERIS, MSI, and ETM+ hue angles. Furthermore, the sensitivity of the link between LCC and different hue angles, as well as vegetation indices (VIs), is assessed in dense and sparse canopies. The results show that using wavelength-independent illuminant data or discrete bands overcalculates the reflectance-based hue angle. Moreover, our proposed hue angle calculated using D65 standard illuminant data is more sensitive to LCC than the existing hue angle using wavelength-independent illuminant data. In dense canopies, the multispectral hue angle has a stronger relationship with LCC than in sparse canopies. The multispectral hue angle generally appears weaker or similar to the red-edge VIs (MTCI and CIred-edge), but stronger than the non(red-edge) VIs (CIgreen, NDVI, NGRDI, and TGI). These findings imply that the multispectral hue angle calculated from visible bands provides the potential to monitor the LCC of large-scale plants.

DOI:
10.1109/TGRS.2023.3322130

ISSN:
1558-0644