Module geodesy.topocentric
Prepared local East/North/Up coordinates and EPSG topocentric conversions.
TopocentricFrame binds an ellipsoid and origin to a reusable right-handed local ENU orientation. It supports both geocentric and geodetic entry points while preserving the distinct pole/origin semantics required by those forms. General Euclidean geometry after conversion to the local frame remains outside this module.
Standards
EPSG method 9836 -- Geocentric/topocentric conversions. EPSG method 9837 -- Geographic/topocentric conversions. EPSG method 9602 is used by the defined 9836/9837 decomposition.
Units
East, north, up, geocentric coordinates, geodetic height, and ellipsoid axes use the same caller-selected linear unit.
Numerics
The frame caches its working-precision origin and orientation. Public float geodetic/topocentric paths retain double working precision across the internal 9602/9836 composition so Earth-scale binary32 intermediates do not unnecessarily destroy local differences.
Performance
Origin conversion and trigonometric orientation are prepared once for repeated point conversion. Checked operations are allocation-free.
Validation
Dedicated validation covers EPSG semantics, pole/origin cases, scalar behaviour, portable properties, and compiler/platform matrices.
See Also
TopocentricCoordinate, TopocentricFrame,
GeodeticCoordinate, GeocentricCoordinate
Date
September 26, 2026
Structs
| Name | Description |
|---|---|
TopocentricCoordinate
|
A local topocentric Cartesian coordinate (east, north, up).
|
TopocentricFrame
|
A prepared local East/North/Up frame. |