Tasseled cap transformation for HJ-1A/B charge coupled device images

Abstract

At-satellite reflectance based tasseled cap parameters were extracted from HJ-1A/B satellite imagery, the charge coupled device (CCD) data of the Chinese environmental satellites that were launched on September 6, 2008. Sixteen scenes selected from the four sensors (HJ 1A CCD1, HJ 1A CCD2, HJ 1B CCD1, HJ 1B CCD2), respectively were used. The objectives are evaluating the consistency of the tasseled cap parameters for four sensors and proposing combined tasseled cap parameters for all four HJ-1A/B CCD. The results indicated that the direction of corresponding tasseled cap vectors of four sensors were almost the same. Then a combined at-satellite reflectance-based tasseled cap transformation was developed based on eight HJ-1A/B CCD scenes representing a variety of landscapes of China in both leaf-on and leaf-off seasons. Extraction combines the principle component transform with Gram-Schmidt Orthogonalization (GSO) process. The accurate brightness was obtained with the help of the first principal component eigenvector, and then greenness and wetness. The fourth one was obtained by the GSO. The first two dimensions (the brightness and the greenness) typically capture over 98%, and the brightness, greenness, and wetness account for over 99.9% of the total spectral variance. The fourth one occupies a very low proportion.