Estimating crop chlorophyll content with hyperspectral vegetation indices and the hybrid inversion method. Issue 13 (2nd July 2016)

• Record Type: Journal Article
• Authors: Liang, Liang; Qin, Zhihao; Zhao, Shuhe; Di, Liping; Zhang, Chao; Deng, Meixia; Lin, Hui; Zhang, Lianpeng; Wang, Lijuan; Liu, Zhixiao
• Is Part Of: International journal of remote sensing. Volume 37:Issue 13(2016)
• Page Start: 2923
• Page End: 2949
• Publication Date: 2016-07-02
• Subjects: hyperspectra -- chlorophyll content -- inversion -- PROSAIL -- random forest regression (RFR); Remote sensing -- Periodicals; Télédétection -- Périodiques; 621.3678
• DOI: 10.1080/01431161.2016.1186850
• Languages: English
• ISSNs: 0143-1161

Abstract

ABSTRACT: A hybrid inversion method was developed to estimate the leaf chlorophyll content (LCC) and canopy chlorophyll content (CCC) of crops. Fifty hyperspectral vegetation indices (VIs), such as the photochemical reflectance index (PRI) and canopy chlorophyll index (CCI), were compared to identify the appropriate VIs for crop LCC and CCC inversion. The hybrid inversion models were then generated from different modelling methods, including the curve-fitting and least squares support vector regression (LS-SVR) and random forest regression (RFR) algorithms, by using simulated Compact High Resolution Imaging Spectrometer (CHRIS) datasets that were generated by a radiative transfer model. Finally, the remote-sensing mapping of a CHRIS image was completed to test the inversion accuracy. The results showed that the remote-sensing mapping of the CHRIS image yielded an accuracy of R 2 = 0.77 and normalized root mean squared error (NRMSE) = 17.34% for the CCC inversion, and an accuracy of only R 2 = 0.33 and NRMSE = 26.03% for LCC inversion, which indicates that the remote-sensing technique was more appropriate for obtaining chlorophyll content at the canopy scale (CCC) than at the leaf scale (LCC). The estimated results of various VIs and algorithms suggested that the PRI and CCI were the optimal VIs for LCC and CCC inversion, respectively, and RFR was the optimal method for modelling.