code: def get_lonlatalts(self):
          
          band = self.filehandle
  
          (xpoints, ypoints), (gcp_lons, gcp_lats, gcp_alts), (gcps, crs) = self.get_gcps()
  
          # FIXME: do interpolation on cartesion coordinates if the area is
          # problematic.
  
          longitudes = interpolate_xarray(xpoints, ypoints, gcp_lons, band.shape)
          latitudes = interpolate_xarray(xpoints, ypoints, gcp_lats, band.shape)
          altitudes = interpolate_xarray(xpoints, ypoints, gcp_alts, band.shape)
  
          longitudes.attrs['gcps'] = gcps
          longitudes.attrs['crs'] = crs
          latitudes.attrs['gcps'] = gcps
          latitudes.attrs['crs'] = crs
          altitudes.attrs['gcps'] = gcps
          altitudes.attrs['crs'] = crs
  
          return longitudes, latitudes, altitudes
docs: Obtain GCPs and construct latitude and longitude arrays.
  
          Args:
             band (gdal band): Measurement band which comes with GCP's
             array_shape (tuple) : The size of the data array
          Returns:
             coordinates (tuple): A tuple with longitude and latitude arrays