Glint correction for the DSF
Posted: Wed Sep 19, 2018 9:31 am
A glint correction for the DSF was added in ACOLITE 20180917.0
The DSF estimates the path reflectance by using the band giving the lowest aerosol optical thickness, hence the use of pixels and bands with severe sun glint is avoided in the aerosol correction. This allows for a separate estimation of sun glint from bands with no expected signal originating from below the water surface (e.g. using the SWIR, as done by Harmel et al., 2018).
The glint correction can be applied to any of the supported sensors (L5/TM, L7/ETM, L8/OLI, S2A/MSI and S2B/MSI), and has to be activated in a settings file, by setting glint_correction=True. The performance of the correction depends on the sensor signal-to-noise ratio and the severity of the glint. Further options are briefly discussed in the user manual.
In the posts below the application of the glint correction is illustrated using imagery of the Mississippi River plume (limit=28.60,-89.80,29.20,-88.75), using a surface reflectance RGB composite and a turbidity product derived from the red band. In the Landsat examples the default masking threshold was increased to 0.05 (l2w_mask_threshold=0.05). The S2A images were merged and processed at 60 m using a masking threshold of 0.08.
The DSF estimates the path reflectance by using the band giving the lowest aerosol optical thickness, hence the use of pixels and bands with severe sun glint is avoided in the aerosol correction. This allows for a separate estimation of sun glint from bands with no expected signal originating from below the water surface (e.g. using the SWIR, as done by Harmel et al., 2018).
The glint correction can be applied to any of the supported sensors (L5/TM, L7/ETM, L8/OLI, S2A/MSI and S2B/MSI), and has to be activated in a settings file, by setting glint_correction=True. The performance of the correction depends on the sensor signal-to-noise ratio and the severity of the glint. Further options are briefly discussed in the user manual.
In the posts below the application of the glint correction is illustrated using imagery of the Mississippi River plume (limit=28.60,-89.80,29.20,-88.75), using a surface reflectance RGB composite and a turbidity product derived from the red band. In the Landsat examples the default masking threshold was increased to 0.05 (l2w_mask_threshold=0.05). The S2A images were merged and processed at 60 m using a masking threshold of 0.08.