libera_utils.footprint_matching.geometry.compute_footprint_bounding_boxes#

libera_utils.footprint_matching.geometry.compute_footprint_bounding_boxes(boresight_lat_deg: ArrayLike, boresight_lon_deg: ArrayLike, subsatellite_lat_deg: ArrayLike, subsatellite_lon_deg: ArrayLike, *, satellite_radius_km: ndarray, fov_halfangle_deg: float = 1.0, n_samples: int = 72) → list[BoundingBox | None]#

Compute the lat/lon bounding box of each of N radiometer footprints on the surface.

Chains: locate each satellite and build the boresight line of sight -> get the PSF angular extent -> rotate each boresight by that extent and ray-trace each ray onto the WGS84 ellipsoid -> assemble a lat/lon box with pole and dateline handling.

Inputs come straight from L1B RAD fields: footprint Latitude/Longitude, Subsatellite_Latitude/Longitude and Radius_of_Satellite_from_Center_of_Earth. The last three place the satellite exactly; the line from it to the footprint is the boresight, so the viewing zenith angle and the scan orientation follow from the geometry rather than being inputs.

Off-Earth views (a fill, non-finite or out-of-range boresight latitude/longitude) are returned as None at their index rather than raising, so the caller can flag them per footprint. Corner rays that run off the limb at a severe angle are truncated at the horizon and the box’s truncated flag is set. Missing ephemeris fields or a footprint not visible from its satellite raises MissingGeolocationError for the whole call instead of hiding among the None entries.

Parameters:

  • boresight_lat_deg (array_like) – Per-footprint boresight centroids (L1B Latitude/Longitude), degrees.

  • boresight_lon_deg (array_like) – Per-footprint boresight centroids (L1B Latitude/Longitude), degrees.

  • subsatellite_lat_deg (array_like) – Per-footprint geodetic spacecraft sub-points (L1B Subsatellite_Latitude / Subsatellite_Longitude), degrees.

  • subsatellite_lon_deg (array_like) – Per-footprint geodetic spacecraft sub-points (L1B Subsatellite_Latitude / Subsatellite_Longitude), degrees.

  • satellite_radius_km (np.ndarray) – 1-D array of each footprint’s spacecraft distance from Earth’s center (L1B Radius_of_Satellite_from_Center_of_Earth), km, one per footprint.

  • fov_halfangle_deg (float, optional) – Instrument FOV half-angle, degrees. Used as a floor on the PSF extent so the box is never smaller than the optical field of view. Defaults to libera_utils.footprint_matching.psf.LIBERA_FOV_HALFANGLE_DEG.

  • n_samples (int, optional) – Number of PSF-perimeter samples. Defaults to _N_PERIMETER_SAMPLES.

Returns:

One entry per input footprint, in input order. None marks an off-Earth view.

Return type:

list[BoundingBox | None]

Raises:

  • ValueError – If an input is more than 1-D, the inputs do not share a length, or satellite_radius_km does not hold one radius per footprint.

  • MissingGeolocationError – If any footprint’s subsatellite point or radius is unusable, or any footprint is not visible from its satellite.