OLI L2 data

avmehta · by **avmehta** » Wed Aug 26, 2020 2:51 pm America/New_York

Hello,
I have been processing a number of OLI images using l2gen. I have a couple of issues/questions: 1)When I visualize the L2 images the mask manager panel is blank!
2) When I display the l2flag raster I see a number 2112 -- I don't know what this number represents! The output L2 data have the following flags but I do not see 2112!
Is this the flag number for valid data?!
Could you please help with these issues?

ATMFAIL   1
LAND   2
PRODWARN   6
HIGLINT   8
HILT   16
HISATZEN   32
COASTZ   64
SPARE   128
STRAYLIGHT   256
CLDICE   512
COCCOLITH   1024
TURBIDW   2048
HISOLZEN   4096
SPARE   8192
LOWLW   16384
CHLFAIL   32768
NAVWARN   65536
ABSAER   131072
SPARE   262144
MAXAERITER   524288
MODGLINT   1048576
CHLWARN   2097152
ATMWARN   4194304
SPARE   8388608
SEAICE   6777216
NAVFAIL   33554432
FILTER   67108864
SPARE   134217728
BOWTIEDEL   268435456
HIPOL   536870912
PRODFAIL   1073741824
SPARE -2147483648

Thank you.
Amita

by **OB SeaDAS - dshea** » Wed Aug 26, 2020 3:14 pm America/New_York

l2flags is a bit field. Your example breaks down like this:

decimal = 2112
hex = 0x0840
binary = 0000 1000 0100 0000

That means bit 6 and bit 11 are on. The first bit is on the right and you start numbering the bits at 0

bit 6 = 64 = COASTZ
bit 11 = 2048 = TURBIDW

don

by **OB WebDev - norman** » Wed Aug 26, 2020 5:21 pm America/New_York

Hi Amita,

There is a tool at the bottom of this page that might help you understand the l2_flags.

https://oceancolor.gsfc.nasa.gov/atbd/ocl2flags/

Try entering 2112 in the field at the bottom right.

Regards,
Norman

by **OB SeaDAS - knowles** » Thu Aug 27, 2020 10:05 am America/New_York

If you are a loading a level-2 file into SeaDAS the Mask Manager panel shouldn't be blank. Make sure your file is being loaded correctly and being recognized as a level-2 file. To determine which "Product reader" SeaDAS is actually using on your file, go to File Manager, click on the filename, select Menu > Analysis > Band Info. It should contain a field something like "Product Reader = SeaDAS-Supported Level 2 Products".

If this isn't working you can always use the Mask Manager to create masks based on the flags. In Mask Manager click on "f(x)" then create a mask based on a single or composite of the selectable level2 flags within the GUI.

Danny

avmehta · by **avmehta** » Thu Aug 27, 2020 6:31 pm America/New_York

Thanks so much Don.
Amita

avmehta · by **avmehta** » Thu Aug 27, 2020 6:32 pm America/New_York

Thank you Norman.
Amita

avmehta · by **avmehta** » Thu Aug 27, 2020 6:32 pm America/New_York

Thanks Danny. Will try that.
Amita