Re-merge S2 bands after GeFolki Coregistration


I am scripting a pipeline to Co-Register 2 Sentinel-2 images through SNAP.

First, I apply a Subset operation to the products in which I choose the area of interest (in common among the products) and all the bands of interest (e.g. B2, B3 and B4).

Then, I apply several times the Subset Operator, this time I use it to create one product FOR EACH band of the master and one product for each band of the slave. Basically, I transform the single product Master_B2-B3-B4 into 3 products: Master_B2, Master_B3 and Master_B4. The same rationale is applied to the slave product.

Now, I apply the Ge-Folki Coregistration operator to coregister each couple of the same band, that is, I coregister Master_Bx with Slave_Bx for x = 2,3,4. It returns me three products: Coregistered_Slave_B2, Coregistered_Slave_B3 and Coregistered_Slave_B4.
Now, I want to merge them in order to have the final Coregistered_Slave as a single product with 3 bands.

My question is, which is the best way to do that? I was thinking to use either Collocation or Create Stack but in this way I would use the Geolocation information and this could alterate the results obtained with the GeFolki coregistration, I guess (?).

What do you think about it?

I tried to check it experimentally but the “problem” is that I am not able to download S2 products that REALLY need a CoRegistration (probably because they are well geolocalized, thus, they can be perfectly overlapped, even without any kind of preprocessing).


I exported the products in .PNG format and then I flipped the slave product upside down. Then, I run the GeFolki Coregistration tool on the png images but the result is still rotated. So, I probably have a problem even bigger, that is, the GeFolki Operator does not work :upside_down_face:

In order to merge your 3 products (having 1 band each) into one product, you can try to use the BandMerge operator.

Thank you for the suggestion. If I will be able to get meaningful results from the GeFolki Operator, I will try to do in this way.