I am trying to use OWT classification with Sentinel 3, I am trying to use Level 2 or Level 1. None of the above work. What kind of product needs the OWT? Does it need a preprocessing step?
It needs OLCI Level 2 data. Actually only atmospherically corrected water spectra, not more.
You need to specify the prefix of the spectral band names. The necessary wavelengths are found automatically. An error will be shown if a wavelength can’t be found.
You could also do you own AC on the L1 data or use the C2RCC. Then you need to change the prefix.
For a standard OLCI L2 water product, you could specify:
Strange for me it works. I get an output.
In your case, it does not pick up the provided prefix for some reason.
Do you have the latest updates? Maybe you restart SNAP?
I restarted snap and it worked.
Hi! Is it not possible to use OWT on Sentinel-2 data?
Hi there, I have never tried, but the OWT was designed for MERIS wavelengths, then adapted to OLCI. What you need is specific bands. Furthermore, it is not really working with the outputs of all atmospheric correction methods (if some of the bands it uses are not corrected it will not work). I would suggest to read the references to see which bands and which units are required and later try again.
Ok, thanks. I will use OLCI then.
Trying to run OWT on C2RCC processed data. Getting the same error: “Not able to find band with prefix ‘reflec’ and wavelength 410.000”. Do you know where would I find the correct prefix of the spectral bands?
Yes, reflec doesn’t work, because C2RCC uses different names.
I depends on how you configure C2RCC.
Either use ‘rhow’ as prefix or if you choose the option ‘Output AC reflectances as rrs instead of rhow’ then you need to define ‘rrs’ as prefix. Take a look at the generated product in the product explorer.
Actually you could also use ‘rhown’ if this option is enabled.
If you select rrs, you should select in the OWT operator as input reflectance the option ‘Radiance_Reflectances’. For rhow the ESA compatible Irradiance_reflectance is the right one.
Thanks for your response. I ran C2RCC on resampled S2B L1C data and choose the option 'Output AC reflectances as rrs instead of rhow’ but only get rrs values from 8 bands. When I try OWT classification, I get the same error. “Not able to find band with prefix ‘rrs’ and wavelength ‘410.000’”. Can the OWT tool work on MSI data?
The problem is that S2 doesn’t have a band at 410nm, also a wavelength at 510nm is missing which would be needed by OWT Coastal Type. So, OWT is not usable with Sentinel-2.