I have a raster of coherence value (SAR interferometry) and a land use shape. I wish to calculate mean coherence value for those areas with a specific land use. I split land use shape into specific classes that I am interested in. So now I have a shapefile of urban areas (multiple polygons) and I wish to know average coherence in all urban areas together.

When I use Zonal Statistics, I only get average value for raster for each polygon separately, but I wish to know average pixel value for all urban areas together. Are there any plugins that I could use? Or am I missing something else?

I am using QGIS 2.12.0.

closed as off-topic by nmtoken, xunilk, Vince, user2856, whyzar Apr 19 '18 at 4:27

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  • 2
    Maybe you should union your polygons (one multipart feature) and use that. – Vince Feb 1 '16 at 12:48
  • @Vince - You should post your comment as an answer =) – Joseph Feb 2 '16 at 15:15
  • I'm not a QGISer. Feel free to write it up if you want. – Vince Feb 2 '16 at 15:17
  • Possible duplicate of Clipping raster with vector boundaries using QGIS? – whyzar Apr 19 '18 at 4:27