Figure 4. Difference images (a) of the five spectral vegetation indices from the two images
acquired on 13 March 2014 (cloud-contaminated pixels were filled with the cloud-free
pixels from 29 March 2014) and on 9 February 2014, and the rubber plantation maps (b)
obtained by thresholding these difference images. The areas of the rubber plantations (ARP)
in these maps were calculated and are shown in (b).