Hi,
I'd like to use the "Straylight Low-Pass 1.5 Pixel Radius (1/r)" filter to create a filtered band. I can do it quite nicely using the GUI. Is there a way to implement this type of filtering using gpt or via command line somehow?
The basic problem is that I would like to create a non-standard straylight mask that does not remove so many pixels as default straylight masking. I can do this just fine if I start with L1A files, but cannot find a way to do it using standard L2 files I get via subscription. Any ideas are appreciated. Thanks,
Dan
Create filtered band using gpt/command line
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Create filtered band using gpt/command line
Dan
Sorry, but there is currently no way to generate a filtered band in SeaDAS via command line (gpt). Hopefully in the future.
Regarding your second statement about L1A and L2, you should explain specifically what you are doing which enables L1A to work for you and L2 to not work for you.
Ideally, for cloud masking via the band filter, you want to do this using the longest NIR rhos product so your filter is interpolating across rhos magnitude values instead of across mask binary values. The standard L2 you get via subscription does not contain the rhos product. The only thing you can do with a standard L2 file would be to create a band from the CLDICE mask (this step can be done at command line (gpt)). Then apply the filter to this CLDICE band and create a mask based on the filtered band. This technique will enable you to adjust how aggressively you expand your cloud mask around the CLDICE values.
There is a SeaDAS poster on this straylight topic which was presented at the International Ocean Colour meeting in 2015, (see upper right corner of poster)
https://www.eposters.net/poster/approaches-to-ocean-color-studies-using-seadas
Danny
Sorry, but there is currently no way to generate a filtered band in SeaDAS via command line (gpt). Hopefully in the future.
Regarding your second statement about L1A and L2, you should explain specifically what you are doing which enables L1A to work for you and L2 to not work for you.
Ideally, for cloud masking via the band filter, you want to do this using the longest NIR rhos product so your filter is interpolating across rhos magnitude values instead of across mask binary values. The standard L2 you get via subscription does not contain the rhos product. The only thing you can do with a standard L2 file would be to create a band from the CLDICE mask (this step can be done at command line (gpt)). Then apply the filter to this CLDICE band and create a mask based on the filtered band. This technique will enable you to adjust how aggressively you expand your cloud mask around the CLDICE values.
There is a SeaDAS poster on this straylight topic which was presented at the International Ocean Colour meeting in 2015, (see upper right corner of poster)
https://www.eposters.net/poster/approaches-to-ocean-color-studies-using-seadas
Danny
Create filtered band using gpt/command line
Thanks, Danny
For L1A files, when I run l2gen, I mask straylight (maskstlight=1), but I call a custom filter file set to 3x3 instead of 7x5, changing two lines in the "msl12_filter.dat" file:
stlight, 5, 3, 3, 1
stlight, 10, 3, 3, 1
This gives me a less aggressive stlight filter, which is what I want to implement on standard L2 files. However, it looks like the ability to apply a filter and create a filtered band is limited to the GUI.
- Dan
For L1A files, when I run l2gen, I mask straylight (maskstlight=1), but I call a custom filter file set to 3x3 instead of 7x5, changing two lines in the "msl12_filter.dat" file:
stlight, 5, 3, 3, 1
stlight, 10, 3, 3, 1
This gives me a less aggressive stlight filter, which is what I want to implement on standard L2 files. However, it looks like the ability to apply a filter and create a filtered band is limited to the GUI.
- Dan