Sentinel 2A Mosaick not smooth - coarse resolution

snap
#1

Hi there!

I am currently working with the toolbox (latest version) and after resampling the Sentinel 2A tiles to one resolution I wanted to make a mosaic of four tiles (Marocco), but despite all tiles looking great after resampling (10m resolution), all except one get a coarse resolution in the final mosaic, so there is a seamline (picture attached). I have the same problem when trying the mosaicing in SAGA or ArcGIS or via the sen2mosaic batch processing. Working with the 1C tiles in SAGA and mosaicking these is no problem, so I guess this is something regarding the 2A tiles that I do not understand. I am fairly new to working with SNAP, so any help is appreciated. I feel like this is a very basic problem due to something I have not considered.

Screenshot 2021-01-07 082432
Screenshot 2021-01-07 0824321323×902 231 KB

Thank you and kind regards.

#2

Do both L2A products look alright before the mosaic?
Looks like the left was stored at 60 m only

#3

They were both resampled to 10m.

#4

have you visually checked the quality of the resampling?

Which operator did you use to create the mosaic? Maybe you can share screenshots on the module and the parameters you selected

#5

Thank you for your reply. One of the tiles must have lacked the quality, even though I am sure I used the same parameters on all four tiles - so thank you very much for that! I mosaicked them again (took some time, slow computer and all), the only thing that remains is a seamline where two tiles overlap at a coastline. I do not know weather a boundary blend or feathering is possible within the mosaicking tool, at least I do not see it.

(Edited, because I uploaded the wrong screenshot, sorry)

Screenshot 2021-01-07 102527
Screenshot 2021-01-07 102527723×878 100 KB
Screenshot 2021-01-07 110021
Screenshot 2021-01-07 1100211130×857 265 KB

#6

The line originates from the different scenes. The atmospheric correction works with parameters which are derived for each scene individually, thus this gives different AC results. There is not much you can do about it.

#7

Okay, thank you. I would have thought there would have been a way to smooth out the boundary of those scenes when mosaicking so that the end result is seamless.

Thank you kindly!