I am working on fusion of two different rasters. One raster is a multi-spectral band having spatial reference GCS-WGS-1984 and other raster is SAR band having spatial reference WGS-1984-polyconic. Prior to fusion, I have registered multi-spectral band with SAR band. So spatial reference of multi-spectral data has been changed to WGS-1984-polyconic. After fusion, I want to compare fused raster with original multi-spectral raster. I tried for re-projecting fused raster to GCS-WGS-1984 in QGIS and ArcMap. But during this process, size of my raster is changed from size of original multi-spectral raster.
How do I overcome this problem in QGIS?