Struct Datum 

pub struct Datum { /* private fields */ }

Horizontal geodetic datum: ellipsoid and its transformation to WGS 84.

Each provided datum uses the EPSG transformation for its home area, with the accuracy EPSG states: a few metres for a modern seven-parameter fit, tens of metres for a continental mean translation. This is the accuracy of the shift, not of the chart; a chart’s own datum note, when present, takes precedence over this table.

Implementations

impl Datum

pub const WGS84: Self

WGS 84: the GNSS datum, and the datum of every Position.

pub const NAD83: Self

NAD83, on GRS 80. Equivalent to WGS 84 at chart accuracy: EPSG 1188 (identity), 4 m.

pub const ED50: Self

ED50, on International 1924: western European charts before ETRS 89. EPSG 1133 (Europe mean), 10 m.

pub const NAD27: Self

NAD27, on Clarke 1866: older US charts. EPSG 1173 (CONUS mean), 10 m.

pub const OSGB36: Self

OSGB36, on Airy 1830. EPSG 1314 (seven-parameter, Great Britain), 2 m.

pub const PULKOVO_1942: Self

Pulkovo 1942, on Krassowsky 1940: Russian and former-USSR charts. EPSG 5044 (GOST R 51794-2001, Russia), 3 m. Published in the coordinate frame convention; stored here in the position vector convention.

pub const TOKYO: Self

Tokyo, on Bessel 1841: Japanese and Korean charts before JGD 2000. EPSG 1230 (Japan and South Korea mean), 29 m; the shift itself exceeds 400 m.

pub const DHDN: Self

DHDN (Potsdam), on Bessel 1841: German charts before ETRS 89. EPSG 1777 (Germany), 3 m.

pub const AGD66: Self

AGD66, on the Australian National Spheroid. EPSG 15788 (Australia mean), 5 m.

pub const SAD69: Self

SAD69, on GRS 1967 Modified. EPSG 1864 (continental mean), 19 m.

pub fn new( name: &'static str, ellipsoid: Ellipsoid, to_wgs84: Helmert, accuracy: Distance, ) -> Self

Datum from its ellipsoid, transformation to WGS 84 and stated accuracy: for datums not in the table, or with parameters from a chart note.

pub const fn name(&self) -> &'static str

Datum name, as in a chart note.

pub const fn ellipsoid(&self) -> &Ellipsoid

Reference ellipsoid.

pub const fn to_wgs84_helmert(&self) -> &Helmert

Transformation from this datum’s geocentric frame to WGS 84.

pub fn accuracy(&self) -> Distance

Stated accuracy of the shift; zero for WGS 84.

pub fn to_wgs84(&self, position: Position) -> Result<Position>

Chart position on this datum → WGS 84.

Placed on the datum ellipsoid at zero height, transformed via ECEF, read back on WGS 84. A ship is within ~100 m of the ellipsoid and the shift tilts the normal by ≤ 0.1 mrad, so dropping height costs about 1 cm.

Errors

KernelError::Indeterminate if the transformed point has no geodetic position; impossible with published parameters, possible with arbitrary Helmert values.

pub fn from_wgs84(&self, position: Position) -> Result<Position>

WGS 84 position (GNSS fix) → position on this datum, for plotting on its chart.

Exact inverse of Datum::to_wgs84 apart from the height dropped at each end: round trip closes to ~1 cm in the datum’s home area, a decimetre or two on the far side of the Earth where its ellipsoid is kilometres from WGS 84.

Errors

As Datum::to_wgs84.

Trait Implementations

impl Clone for Datum

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Datum

impl Debug for Datum

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Datum

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Datum

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Datum