Added FIXME comment.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

enpt/processors/spatial_transform/spatial_transform.py

@@ -575,6 +575,8 @@ class RPC_3D_Geolayer_Generator(object):
             args = [(coeffs, self.enmapIm_cornerCoords, self.enmapIm_dims_sensorgeo, idx)
                     for coeffs, idx in zip(rpc_coeffs_list, band_inds)]
 
+            # FIXME: pickling back large lon/lat arrays to the main process may be an issue on small machines
+            # NOTE: With the small test dataset pickling has only a small effect on processing time.
             with Pool(self.CPUs,
                       initializer=mp_initializer_for_RPC_3D_Geolayer_Generator,
                       initargs=(self.dem,)) as pool: