Safe bands in separate files

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#21

I’m also a bit puzzled. But I’m also not an expert for Maja a and MUSCATE data.

@oana_hogoiu can you help further?
Maybe @OHagolle is around and can help?

#22

thanks Marco…it is always a plesure to get your feedback =)…even if you don´t know

#23

Thanks @marpet for pinging me. I am not a Snap user, and I don’t know the converter,
MAJA has two types of outputs.

  • L2A products with FRE extension (Flat reflectance, after terrain correction)
  • L2A products with SRE extension (Surface reflectance, without terrain correction)

The SRE (Surface reflectance without terrain correction) might have some negative values, as there is noise in the atmospheric correction and as we also correct flagged cloud shadows from atmospheric effects. But -0.3 seems a bit too much, especially in Germany.

In the FRE product, negative values are set to zero.

So we have two possibilities:

  • either a SRE was used by the converter (but the minimum and maximum values look a bit odd, even if negative values, or values above 1 exist)
  • or there is a bug in the converter, and SNAP should ask the company who wrote and validated it.

Maybe Christian could have a look to the histogram of the SRE file (but I am not fully sure DLR keeps it).

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#24

Thanks @OHagolle and @marpet for looking into this topic.

I really want to understand what is goning on and what is “safe” to use.

So I took another tile and did import it into SNAP with and without the converter.

Reflectance_SNAP_02.pdf (177.7 KB)

FRE, as said brings only values above 0. But still the Max 2.224 seem high. But as I still don´t feel expert enough I would like to not give any explanations.

What do you think, does the MUSCATE converter work correctly?
Is the downloaded MAJA product okay?

Where would you do further investigation to be sure?

Cheers
Christian

#25

Hi,

Is there anybody who knows about the MUSCATE importer…?

I have the MAJA and WASP datasets

both overlay perfectly with the original data:
MAJA_WASP_01

The 5m messurement is for illustrating.

I import the MAJA dataset with the MUSCATE importer into SNAP
Reprojecting EPSG 25832
Clipping
Export

The WASP Dataset I import manually “Open product”
Band math / 10000
Reprojecting
Clipping
Export

Now the two exported products are shifted by around 5m

MAJA_WASP_02
MAJA_WASP_02605×524 34.3 KB

Why does this happen…?

I would be so great to get some help with this…

Cheers
Christian

#26

Hello,

The last version of MAJA is compatible with S2 product. It will foreseen in snap9.
If the last version of MAJA is integrated with S2 input compatiblity, is it a better solution to your issue or you have to use MUSCATE product?