Display of pixel values for geophysical OLCI products

s3tbx
#1

Hi

I can’t figure out why geophysical OLCI products (algal_2, total_susp, etc.) display as log10 values in the Pixel Info window. I don’t see a place in preferences to change this. Reflectance pixel values display normally. Any ideas? Thanks,

Dan

#2

Actually the values should be displayed unscaled. The values are stored log10 scaled in the NetCDF files but we unscale them when reading the data. Why do you think they are log10 scaled?

#3

Thanks, Marco

The reason I say this is because I see negative values displayed and the
units say “log10(m^-1)” for yellow substance for example.

Dan

#4

Which version are you using?
As you can see on my screenshot that there is not Log10 in the units. I’m using the current SNAP 5

image.png1858×1080 437 KB

#5

Marco,

I am using SNAP 5. However, I think I may have used the wrong toolbox to
process from L1, as your product list looks different than mine. I used the
FUB/WeW Water Processor under the “Optical/Thematic Water Processing” menu.
It did work and I was able to get L2 geophysical products, but I fear that
this processor may not be the right one for S3 OLCI data. I think this may
be the one for MERIS data. Which is the right processor to use? Thanks!

Dan

#6

I’ve used a real OLCI Level2 Water product.

You have discovered a undocumented feature of the FUB. Please don’t use it for OLCI, as you assume it is intended for MERIS.

#7

Actually there is no L2 Water processor yet.
There is the C2RCC processor in development, but not yet officially released.


You can build it on your own and install it in SNAP, as documented in the readme.

2 Likes
#8

Ok. If I have an L1 OLCI EFR product, what is the best way to get to L2?

#9

Official OLCI L2 data is not released too. It’s still in validation phase.
The best way at the moment is the above mentioned C2RCC processor.

#10

Thanks, Marco. I have installed the C2RCC processor it’s working.

Dan

#11

Dear Macro,
I have installed the C2RCC from github according to the document in the readme.
The processing by using the anonymous parameter is OK, but I don’t know how to config the processing parameters when I want to adapt some parameters to process inland lakes, China.
Are there some instructions about the meaning for every parameter in the processing GUI?

Best Regards,
zhigang

#12

There is no documentation yet. That’s one of the reasons why it is not yet publicly released.
But there is nothing mystical about the parameters. I think the names and the descriptions are already a brief but sufficient documentation. For the time being.
In the GUI you can see the description if you hover the mouse over the parameter.

#13

Thanks Marco. Actually, the initial atmospheric correction test by anonymous parameters in taihu Lake( turbid Lake, China) seems failed, a quick-RGB(Rrs) composited image deviated from the real situation in taihu lake. I will make a deeper analysis and try to modify some processing parameters to validate again.
Looking forward to the public release of C2RCC.

Regards,
zhigang