Struct Helmert7

Seven source-to-target Helmert parameters with rotation convention encoded in the type.

struct Helmert7(T, HelmertConvention convention)
  
if (isGeodesyScalar!T);

Canonical storage uses the geocentric coordinate linear unit for translations, radians through Angle!T for rotations, and a dimensionless scale difference dS, with multiplication factor M = 1 + dS. .init is the identity transformation.

fromArcSecondsAndPpm accepts the common EPSG interchange representation: rotations in arc-seconds and scale difference in parts per million. EPSG 1033 Position Vector and EPSG 1032 Coordinate Frame use opposite signs for equivalent rotations; use toCoordinateFrame or toPositionVector to convert the parameter representation without changing the represented source-to-target transformation.

Properties

NameTypeDescription
rotationX[get] Angle!TX-axis rotation, canonically stored in radians.
rotationY[get] Angle!TY-axis rotation, canonically stored in radians.
rotationZ[get] Angle!TZ-axis rotation, canonically stored in radians.
scaleDifference[get] TDimensionless scale difference dS.
scaleFactor[get] TMultiplication factor M = 1 + dS.
translationX[get] TX-axis translation.
translationY[get] TY-axis translation.
translationZ[get] TZ-axis translation.

Methods

NameDescription
fromArcSecondsAndPpm (translationX, translationY, translationZ, rotationXArcSeconds, rotationYArcSeconds, rotationZArcSeconds, scaleDifferencePpm) Construct from the common EPSG arc-second/ppm representation.
fromCanonical (translationX, translationY, translationZ, rotationX, rotationY, rotationZ, scaleDifference) Construct Helmert parameters from canonical units.
tryFromArcSecondsAndPpm (translationX, translationY, translationZ, rotationXArcSeconds, rotationYArcSeconds, rotationZArcSeconds, scaleDifferencePpm, result) Construct from the common EPSG arc-second/ppm representation without throwing.
tryFromCanonical (translationX, translationY, translationZ, rotationX, rotationY, rotationZ, scaleDifference, result) Construct Helmert parameters from canonical units without throwing.

Example

Example using struct Helmert7(T, HelmertConvention convention) if (isGeodesyScalar!T). 

import geodesy;

const source = GeocentricCoordinate!double.fromComponents(
    3_657_660.66, 255_768.55, 5_201_382.11);

const positionVector = PositionVectorHelmert!double
    .fromArcSecondsAndPpm(
        0.0, 0.0, 4.5,
        0.0, 0.0, 0.554,
        0.219);

const target = source.applyPositionVectorHelmert(positionVector);
const coordinateFrame = positionVector.toCoordinateFrame;
const sameTarget = source.applyCoordinateFrameHelmert(coordinateFrame);

assert(target == sameTarget);