Sentinel-2 L2A products cannot be mosaiced in SNAP 3

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Hello everybody,

The L2A sentinel-2 images produced with Sen2cor cannot be mosaiced. When I tried to do that in SNAP 3 I received a message saying that this operation is not possible at present because the products (tiles) to be mosaiced contain bands of different sizes. Indeed, we have in each tile a folder with 10m, a folder with 20m and another with 60m resolution.

Kind regards

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SNAP 3 does not support mosaicing when one of the input product has differently sized bands (as is the case with S2). You have two options to create a mosaic anyway:

(a) You can use one of the dedicated readers to open the product. You will be asked which one to use when you attempt to open the product in SNAP Desktop. Please notice that these readers support upsampling, but not downsampling. This means that bands of a finer resolution than the one selected will be omitted from the product, while missing values in bands of a coarser resolution will be interpolated. So for S2 you would have to take the reader for 60m to include all bands.
(b) Use the Resampling operator that has been introduced with SNAP 3. It is located at Raster->Geometric Operations and enables you to bring all bands of a product to the same size. The resampling operator supports both upsampling and downsampling.

After you have done one of these to each affected source product, you can create the mosaic.

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Dear @TonioF

Thank you very much for these explanations. However I miss something in the explanations:

  • You say “bands of a finer resolution than the one selected will be omitted from the product”; this would mean that if I import with a 10m reader nothing will be omitted, since there is no finer resolution, and the 20m and 60m would be re-sampled at 10m. Actually I am only interested by the 10m resolution;

  • If the above is correct (?) then when you say “So for S2 you would have to take the reader for 60m to include all bands” I don’t understand since according to the first statement all finer resolutions i.e. 20m and 10m, should be dropped since they are finer than 60m???

There is probably something I misunderstand in your explanations and I would be greatful if you could elaborate a little bit.

Best regards.

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Sorry, I was wrong there at one point. What I should have written was “So for S2 you would have to take the reader for 10m to include all bands”. I checked though and found that the 60m reader currently also reads all bands, so you should be off well with all readers. As you are interested in 10m, you should take the 10m reader, then.

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Thanks @TonioF. Appreciated.

Best regards