Comparing two SLSTR L1 products


#1

I’m trying to compare two SLSTR L1 products of a similar area from one day to the next - I would like to calculate statistics for the image in the overlapping region for one band. How do I restrict the statistics (or histogram) function to compute over just the region common to the two images?

Or is there a better way to compare the two - I also tried some of the options for creating co-located images, but had a message saying it could not procede because the product contains bands of different resolutions (1km and 500m). I’m only interested in S8 though, so don’t care about the others in this case - is there a way to do this just for one band?


#2

This ca be done by drawing a rectangle or polygon in the view, afterwards select it with the selection tool and then right click in the view and choose ‘WKT from Geometry’. Copy the text.

Then you can go into the other scene and select from the context menu ‘geometry from WKT’. Paste the text.
In the statistics tools you can choose the geometry as mask:

You can collocate both products but as suggested by SNAP you need to resample first. Due to the incomplete of the multi-resolution products. But actually it is not a big deal.
Resample both to the resolution of the S8 band, then create a subset which contains only the S8 band (you can do spatially tailor the product too), then do the collocation.
If you only save the last resulting product to disk it will not take much time.


#3

Thank you!

I could only seem to get the geometry to appear as a mask in the statistics tool after resampling both images though. It just didn’t appear in the list when I tried to do it without any resampling.

Thanks!