Mosaicing coherence maps black bars


I am trying to create a coherence map the size of the Netherlands by using scenes from multiple S1 tracks(t33, t88, t15, t161, t139)

The final map should be a coherence map as geotiff with approximately 50x50m pixels.

I manage to generate the coherence values in the valid coordinate system with the following sequence

  • Radar -> Sentinel-1 TOPS -> TOPSAR split
  • Radar -> Apply Orbit file
  • Radar -> Corregistration -> S1 Tops Corregistration -> Back Geocoding
  • Radar -> Interferometric -> Interferogram formation
  • Radar -> Sentinel-1 TOPS ->TOPSAR Deburst
  • Radar -> Geometric -> Radar Range Doppler -> Terrain Correction

However, when we try to stich these together (using Radar -> SAR Mosaic) it provides black stripes at the edges. An example can be seen below.
I have tried to play around with the feather parameter, but that doesn’t give the right result. Often, one of the two coherence maps is ignored.

Coherence map 1:

Coherence map 2:

Mosaic with feather:

Mosaic without feather:

Does anyone have any idea what I am doing wrong?

I have searched the forum and saw similar issues, but the answer are unclear what to do exactly.


Somehow the nodata values are not applied correctly. Can you please check the valid pixel expression (under raster properties) of the output product?

If the data is already geocoded, you can also use Raster > Geometric Operations > Mosaicing
Would be worth a try.