SNAP plugin to import S2 L2A products from Theia


#1

Hi S2tbx developers,
I have seen in the release notes of SNAP 6.0.1 updates that a MUSCATE reader for Theia L2A products (https://theia.cnes.fr) generated with MAJA has been added. That’s great, thanks for that !

Where could I find some documentation about it ?
Best regards,
Olivier


#2

Just to put my question on top of the list :slight_smile:
@obarrilero, is there any documentation ?
Thanks !
Olivier


#3

Salut Olivier,

sorry for the late reply. The documentation is not yet available, but we have used the product description available in the link below (I am sure that you know it very well). If you are interested in some particular point, please, do not hesitate to ask me and I will try to clarify you how it has been implemented.

https://theia.cnes.fr/atdistrib/rocket/#/help

Some details of the current implementation:

  • they are read both reflectances, with and without the correction of slope effects.
  • the angle bands are generated by using the information in the metadata (similar as it is made in the S2 SAFE reader)
  • the masks are interpreted by using the different bits.
  • they are supported the products downloaded from Theia, but not the output obtained directly by using MAJA.

Of course, any comment or suggestion is welcome. For example, do you think that it would be better to use a property for opening only the reflectances with or without slope correction instead of opening both? Is the reader missing any important information?

Regards,
Omar.


#4

Hi Omar,
I am not much a SNAP user. My intention was to make an announcement of the availability of that plugin on CESBIO’s blog, so that users know this solution is available. I also wanted to include a link to some documentation, but if does not exist, I’ll just make the announcement.
Thanks, anyway !

I think it is OK to open both types of products.
Best regards,
Olivier


#5

Dear developers,

I am trying to use the S2Resampling Processor on a Sentinel-2 Theia L2A product.
Unfortunately the operator gives the error ‘Invalid S2 source product’.

Are you planning to make the products opened using the Sentinel-2 Toolbox MUSCATE Reader compatible with the S2Resampling operator in the future releases of SNAP?

I think that the proposal by @obarrilero for opening only the reflectances with or without slope correction instead of opening both could help to make the product compatible with the operator.

Regards,

Federico


SNAP LAI Calculate on THEIA S2A Images
#6

Hi @FedericoF,

Thank you for your suggestion, I have just added this improvement to our issue tracker. I will try to include it in the next release.

Regards,
Omar.


#7

Hi @obarrilero,

thank you for considering my suggestion.

I have a new issue related to the Sentinel-2 Toolbox MUSCATE Reader.
The different versions of Sentinel-2 Theia L2A products (v1.4 and v1.7) contain different sets of masks.
I have noted that the Sentinel-2 Toolbox MUSCATE Reader is not importing some of the masks for older v1.4 products, even if they exists in the product (e.g. masks ‘MG2’). Can this behaviour be checked?

Regards,

Federico


#8

Hi @FedericoF,

yes, this will be checked. In fact, the problem that we had in the S2Resampling is that we needed some masks that were not present in the old products (the detector footprints).

Regards,
Omar.


#9

In addition to the abovementioned issues, I have noticed that some MUSCATE products can not be opened in SNAP by directly importing the ZIP file. The error ‘No appropriate product reader found’ is reported. When the same product is unzipped it can be opened without any problem.

It does not seem to be related to a specific product version, and occurs for example for product:

SENTINEL2A_20170315-101214-518_L2A_T32TPR_D.zip

Hope this may help to find the cause of the problem.

Federico