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.