|
The loss of satellite data over water because of sun glint contamination represents a high cost financially and scientifically. Although many glint removal algorithms have been developed, glint contamination can remain problematic, especially in turbid waters. In the present study, we propose a correction for sun glint in turbid waters in the absence of SWIR bands. This method could for example be applied to imagery from the Pléiades and Planetscope constellations. Our method has been developed and tested using (1) in situ multi-angle measurements of surface reflectance collected with a PANTHYR autonomous hyperspectral radiometer deployed near Ostend, and (2) a set of metre-scale Pléiades stereo imagery taken in the Belgian coastal zone, with one image of the stereo pair looking into the sun glint and one looking away from the sun glint. The method uses combinations of spectral bands for which a linear relationship is observed in water reflectance, and a constant band ratio for glint reflectance directly calculated from the glinted image. To be adapted to a high range of turbidity conditions, a switching approach between band combinations is used. Glint removal correction was successfully applied in association with the ACOLITE Dark Spectrum Fitting (DSF) atmospheric correction. Results show a good performance in terms of glint removal, and the average overestimation is reduced to less than 20 % in visible bands.
|
