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Abstract
To validate the HJ-1 B charge-coupled device (CCD) vegetation index (VI) products, spectral reflectance data from EO-1 Hyperion of a close date were used to simulate the band reflectance of the HJ-1 B CCD camera. Four vegetation indices (the normalized difference vegetation index (NDVI), the ratio vegetation index (RVI), the soil adjusted vegetation index (SAVI) and the enhanced vegetation index (EVI)) were computed from both simulated and actual HJ-1 B CCD band reflectance data. Comparisons between simulated and actual HJ-1 B CCD band reflectance data, as well as that between simulated and actual HJ-1 B CCD vegetation indices were implemented to validate the VI products of the HJ-1 B CCD camera. The correlation coefficients between simulated and actual HJ-1 B CCD band reflectance data were 0.836, 0.891, 0.912 and 0.923 for the blue, green, red and near infra-red bands, and the correlation coefficients between simulated and actual HJ-1 B CCD VIs were 0.943, 0.926, 0.939 and 0.933 for SAVI, RVI, NDVI and EVI. The standard deviation of differential images between actual and simulated HJ-1 B CCD VIs are 0.052, 0.527, 0.073 and 0.133. The results show that the VI products from the HJ-1 B CCD camera are consistent with the simulated VIs from Hyperion, which proves the reliability of HJ-1 B CCD VI products.
Acknowledgements
The authors thank all of the staff and students at the Institute of Remote Sensing Applications (Chinese Academy of Sciences) who have been involved in acquiring and processing the remote-sensing data used in this study. Additionally, we thank the CRESDA for providing the HJ-1 CCD data. We would also like to thank three anonymous reviewers for their helpful and constructive comments on the manuscript. The help of Dr Zengyuan from IRSA, CAS and Dr Li Ainong from IMDE, CAS in revising the manuscript is highly appreciated.
The research is supported by the National Natural Science Funds of China (40801144, 41171331), the Knowledge Innovation Programme of the Chinese Academy of Sciences (KSCX-YW-09-01, and the Special Research Project for Application of HJ-1 Data (2009A01A1000, 2009A01A0900).
