code: def transform_grid_from_reference_frame(self, grid):
          
          transformed = np.add(grid, self.centre)
          return transformed.view(TransformedGrid)
docs: Transform a grid of (y,x) coordinates from the reference frame of the profile to the original observer \
          reference frame, including a translation from the profile's centre.
  
          Parameters
          ----------
          grid : TransformedGrid(ndarray)
              The (y, x) coordinates in the reference frame of the profile.