Issue processing tile

[MolettoLobos]

Hi sen2like team,

I'm encountering an issue when processing tile 19KEP (and also tested with neighboring tile 19KEQ where worked perfectly) using the latest version of sen2like (v4.5). The processing fails during the MGRS to latitude/longitude conversion step due to what seems to be a hardcoded MGRS suffix.

Here is the traceback I receive for tile 19KEP:

Traceback (most recent call last):
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/sen2like.py", line 367, in <module>
    sys.exit(main(sys.argv[1:]))
             ^^^^^^^^^^^^^^^^^^
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/sen2like.py", line 358, in main
    process_tile(tile, _search_url, args, date_range.start_date, date_range.end_date)
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/sen2like.py", line 297, in process_tile
    process_an_input_product(tile, input_product, config, args, _tile_ref_image)
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/sen2like.py", line 208, in process_an_input_product
    process.run()
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/core/product_process.py", line 94, in run
    self._preprocess()
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/core/product_process.py", line 164, in _preprocess
    proc_block.preprocess(self._product)
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/s2l_processes/S2L_Nbar.py", line 433, in preprocess
    lat = product.mtl.get_scene_center_coordinates()[1]
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/agrospace/agrospace/sen2like_software/sen2likev4-5/sen2like/sen2like/sen2like/core/readers/sentinel2.py", line 370, in get_scene_center_coordinates
    lat, lon = m.toLatLon(self.mgrs + '5490045100')
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/agrospace/miniconda3/envs/sen2like4.5/lib/python3.12/site-packages/mgrs/__init__.py", line 103, in toLatLon
    core.rt.Convert_MGRS_To_Geodetic(c, plat, plon)
  File "/home/agrospace/miniconda3/envs/sen2like4.5/lib/python3.12/site-packages/mgrs/core.py", line 208, in check_error
    raise MGRSError(msg)
mgrs.core.MGRSError: Error in "Convert_MGRS_To_Geodetic": MGRS Errors

It seems that appending '5490045100' to self.mgrs results in an invalid MGRS string, which causes the Convert_MGRS_To_Geodetic method to fail.

I believe this issue could be resolved by either:

Avoiding the hardcoded addition of '5490045100', or

Ensuring that self.mgrs is complete and properly formatted before attempting the conversion.

For reference, I’ve attached the complete log file from the run:

sen2like.log

Please let me know if any additional information would be helpful.

Best regards,
Italo

[telespazio-tim]

Hi Italo and everyone,

This condition can occur along the 24 degree South parallel:

• Below the 24 degree South parallel, MGRS coordinates system expects a “J” and above a “K” letter, however the name of the Sentinel-2 MGRS tile is fixed.
• Sometimes the S2 MGRS tile centre is located just above the 24 degree South parallel and K is fine in the MGRS nomenclature,
• Sometimes the S2 MGRS tile centre is located just below the 24 degree South parallel and it that case it crashes as K below 24 ° S cannot exist… but replacing ‘K’ by the letter ‘J’ points to the same exact point on Earth.

So, as discussed before there is a workaround, change function get_scene_center_coordinates in module core.readers.sentinel2 with

def get_scene_center_coordinates(self):
    m = mgrs.MGRS()
    try:
        lat, lon = m.toLatLon(self.mgrs + '5490045100')
    except:
        print(f'Warning: translation of MGRS Sentinel-2 {self.mgrs} tile code for lat lon conversion')
        lat, lon = m.toLatLon(self.mgrs.replace('K', 'J') + '5490045100')
    return lon, lat

We will fix it in more reliable way in a future patch release.

[MolettoLobos]

Hi,
I'd also like to suggest an update to the sen2cor_client.py function, as it may be affected if the Sen2Cor setup is set. Below is the updated version of the function, in case others encounter the same issue.

from mgrs.core import MGRSError


def get_mgrs_center(tilecode: str, utm=False) -> tuple:
    """
    Get MGRS tile center coordinates in native tile UTM or WGS84.

    Args:
        tilecode (str): tile to get center coords.
        utm (bool, optional): Flag for output SRS. Defaults to False.

    Returns:
        tuple: (lat, lon) if utm=False, else (utm_zone, hemisphere, easting, northing)
    """
    if tilecode.startswith('T'):
        tilecode = tilecode[1:]

    centercode = tilecode + '5490045100'
    m = mgrs.MGRS()

    try:
        if utm:
            return m.MGRSToUTM(centercode)
        return m.toLatLon(centercode)

    except MGRSError:
        # Try replce problematic letter (K to J)
        fallback_code = tilecode.replace('K', 'J') + '5490045100'
        try:
            if utm:
                return m.MGRSToUTM(fallback_code)
            return m.toLatLon(fallback_code)
        except MGRSError:
            raise ValueError(f"Failed to convert MGRS code: {tilecode} (even after fallback)")