Glint correction for WorldView-2 imagery

[cio]

Hi Quinten,

I've been trying to atmospherically correct WV imagery but each time I tried it with the glint correction set to True, it always comes as False (in the setting file) despite enabling it during atmospheric correction. Wondering if I glint correction is possible with WV (and GeoEye) images in the latest ACOLITE.

Chris.

[quinten]

Hi Chris

Setting dsf_residual_glint_correction=True works fine here. Perhaps you are using the settings files wrong, e.g. editing the file in config/defaults.txt which will get overridden by the defaults in config/defaults/WorldView2.txt This is not a recommendation to edit that file either.

I would recommend creating a settings file just with the settings you want to change, specifying an inputfile and output and running that. For example:

Code: Select all

output=/your/output/path
inputfile=/your/inputfile
dsf_residual_glint_correction=True

Quinten

[cio]

Thanks so much Quinten!!!

[quinten]

Hi Chris

Glad it helped! Note that for WV2 all the signal in the NIR1 band after atmospheric correction is treated as glint, so use this option only where you expect all the residual NIR1 reflectance to be caused by glint. In the presence of floating stuff, turbid waters, land/vegetation adjacency, bottom reflectance (for extremely shallow clear waters), ... the correction may not behave as expected.

Quinten

[cio]

Hi Quinten,

Thanks for the extra explanation!

I also tried glint correction for a WV4 (4 band) imagery but looks like there's no different between before and after glint correction. Is there anything in particular to change in the setting for WV4?

[quinten]

Hi Chris

Which band wavelengths do you have available in the image? It is also possible that the file/band set is not identified correctly. If you could share the L1 bundle for development purposes only I could take a look.

If there is no NIR1 band available, you will probably need to change the glint detection wavelength range, but note that at shorter wavelengths there can be more issues caused by assuming all the signal comes from glint.

I put the WV default to select a band between 800-900 nm, i.e. the NIR1:

Code: Select all

dsf_residual_glint_wave_range=800,900

I hope this helps!

Quinten