Optical correction of scene fractions for estimating regional scale ocean coral abundance in Fiji

Spectral mixture analysis is used to separate coral and water components at sub-pixel scales for a regional scale transect of SPOT imagery across Savusavu Bay, Fiji. Coral fractions on the ocean floor are estimated using empirical optical corrections from mixture fractions obtained from in situ reflectance profile measurements and with reference to a digitised bathymetric chart. Additional corrections are applied to estimate live coral abundance by removing the signal component contributed by coral debris. Issues involved in regional scale applications are discussed in the context of future airborne and satellite image applications.