dem_geocentric_grid — DEM geodesy op

• Data kinds: depth → pointmap

• Call: import fullseye as fs; fs.ledger.dem_geocentric_grid(dem, lat0_deg, lon0_deg, cell_size, spherical=False) (to call the implementation directly, import demops; demops.dem_geocentric_grid(dem, lat0_deg, lon0_deg, cell_size, spherical=False); from the registry, opsdem.get("dem_geocentric_grid"))

Usage

Converts each DEM cell into coordinates as seen from the Earth's center.

Treats an (H, W) elevation grid as a local plane whose north-west corner is at (lat0_deg, lon0_deg), and maps each cell to ECEF (default) or to geocentric spherical coordinates.

Args:

dem: (H, W) elevation [m].

lat0_deg / lon0_deg: latitude/longitude of the grid's north-west corner [degrees].

cell_size: cell size [m]. Assumed equal in the latitude and longitude directions

(Web Mercator tiles are like that.

See dem_cell_size_webmercator).

spherical: if True, returns (radius r[m], geocentric latitude[deg], longitude[deg]).

If False (default), ECEF (x, y, z) [m].

Returns:

(H, W, 3).

★ Geocentric latitude is not geodetic latitude. The latitude returned with spherical=True is the angle seen from the Earth's centre, and differs from map latitude (the angle the ellipsoid normal makes with the equatorial plane) by up to 0.19 degrees. To get back to the map, pass the ECEF side

to dem_ecef_to_geodetic.

Detailed usage guide

• dem_terrain_analysis family guide

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• dem_geodesy_tour — py -3.11 examples/dem_geodesy_tour.py

Ops the type connects to (they accept pointmap as input)

—

Same category (geodesy)

dem_geodetic_to_ecef · dem_ecef_to_geodetic · dem_earth_curvature_drop · dem_cell_size_webmercator · dem_geodetic_slope · dem_geoid_height · dem_height_frame_convert · dem_height_frame_residual

*Provenance: demops.py — DEM operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.