Gaps after Mosaicing S1 images in SNAP


I have mosaiced few tiles of Sentinel 1 in SNAP using Mosaic tool. However, the mosaiced product is having some line gaps. Can I get the mosaiced product without gaps, if not, how can I fill the gaps using above and below pixels in SNAP.

Thank you

have you pre-processed the S1 data before the mosaicing?

Can you please post a screenshot of the result?

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Yes I have pre-processed the data in the order of ------- Radiometric Calib (Sigm0), Speckle Filtering (Refined Lee), Terrain Correction (RTDC using SRTM 1sec HGT Auto Download), Linear to db. Then I mosaiced all the tiles of VH_db pol and the result is given below in the screenshot:

there is a tool for border noise removal of S1 data which maybe helps.
Furthermore, you can select “weighted average” in the mosaic step.

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Thankyou, I will try and update you.

For Border noise removal, I am getting the following error

Can you please elaborate a bit on how to use “weighted average” in the mosaic step, as I am not able to find it.

Thank you

It’s in the SAR-Mosaic under the Radar-menus of SNAP.

Border noise removal has to be applied before the mosaicing.

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Apply border noise removal, calibration, terrain correction and finally SAR mosaic. In the mosaic parameters you can also specify a feathering area. If there is sufficient overlap between the scenes, you could add a 10 pixel feathering area which will remove the border pixels by 10 pixels. Also, select the weighted average to blend the overlapping pixels by weight given by the distance to the scene edge.


Dear #Iveci and #ABraun, I followed the steps as you mentioned. I added a 15 pixel feathering area and the gap reduced, however the gap in North-south direction is not having any effect of the process and only the east west gap reduced, however the line gap still exists.

Is your SNAP fully updated?

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SNAP 6 version, I am having

Did you Check for Updates and install them? Your screenshort implies you did not.

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I have installed plugins. Is there any other updates required, if so, please guide regarding the installation steps.
Thank you

There is a “check for updates”-button in the Plugins-window. It is also available under the Help-menu.

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Thank you, I have updated it, i will check again and update about the results

I installed the updates, I have put feathering pixels to 20 and the line gaps got reduced however, it is still there. Any other suggestions?

You can try slice-assembly to reconstitute the whole data-takes. This will however generate larger products so processing-time may suffer.

ps. Doesn’t the SAR mosaic wizard solve your issues? That at least is the purpose of it - please let us know if it does not help you to solve your problems.


Thank you for the reply #mengdahl

I will try slice-assembly to reconstitute the whole data-takes and will update you about the results.

SAR mosaic wizard has two issues:

  1. After giving a feathering pixel to 20 with weighted average and normalisation buttons checked, the gaps in range direction get reduced (some gaps still exist) but in azimuth direction there is no change.

  2. It doesnot mosaic all the tiles, in my case sometimes it mosaics all the tiles while at other times it doesnot take the tiles located on west side. Under Raster-----Mosaic options we have the freedom to enlarge the border by dragging it manually if it falls on the boundary of the tiles to be mosaiced, that freedom is not avilable under Radar----- SAR mosaic wizard.

If anyother details are required in this context, I will happy to discuss.

Oh Wow, thanks pal, this turned out to be really helpful