org.opengis.referencing.datum
Interface Ellipsoid

All Superinterfaces:

Info

public interface Ellipsoid

extends Info

Geometric figure that can be used to describe the approximate shape of the earth. In mathematical terms, it is a surface formed by the rotation of an ellipse about its minor axis. An ellipsoid requires two defining parameters:

• semi-major axis and inverse flattening, or
• semi-major axis and semi-minor axis.

Version:

Abstract specification 2.0

Author:

ISO 19111, OpenGIS® consortium

UML identifier (abstract type): CD_Ellipsoid

Method Summary

Unit	getAxisUnit() Returns the linear unit of the semi-major and semi-minor axis values.
double	getInverseFlattening() Returns the value of the inverse of the flattening constant.
double	getSemiMajorAxis() Length of the semi-major axis of the ellipsoid.
double	getSemiMinorAxis() Length of the semi-minor axis of the ellipsoid.
boolean	isIvfDefinitive() Indicates if the inverse flattening is definitive for this ellipsoid.
boolean	isSphere() true if the ellipsoid is degenerate and is actually a sphere.

Methods inherited from interface Info

getIdentifiers, getName, getRemarks

Method Detail

getAxisUnit

Unit getAxisUnit()

Returns the linear unit of the semi-major and semi-minor axis values.

Returns:

The axis linear unit.

getSemiMajorAxis

double getSemiMajorAxis()

Length of the semi-major axis of the ellipsoid. This is the equatorial radius in axis linear unit.

Returns:

Length of semi-major axis.

UML identifier (mandatory attribute): semiMajorAxis

getSemiMinorAxis

double getSemiMinorAxis()

Length of the semi-minor axis of the ellipsoid. This is the polar radius in axis linear unit.

Returns:

Length of semi-minor axis.

UML identifier (conditional attribute): secondDefiningParameter.semiMinorAxis

getInverseFlattening

double getInverseFlattening()

Returns the value of the inverse of the flattening constant. The inverse flattening is related to the equatorial/polar radius by the formula ivf = r_e/(r_e-r_p). For perfect spheres (i.e. if isSphere() returns true), the Double.POSITIVE_INFINITY value is used.

Returns:

The inverse flattening value.

UML identifier (conditional attribute): secondDefiningParameter.inverseFlattening

isIvfDefinitive

boolean isIvfDefinitive()

Indicates if the inverse flattening is definitive for this ellipsoid. Some ellipsoids use the IVF as the defining value, and calculate the polar radius whenever asked. Other ellipsoids use the polar radius to calculate the IVF whenever asked. This distinction can be important to avoid floating-point rounding errors.

Returns:

true if the inverse flattening is definitive, or false if the polar radius is definitive.

isSphere

boolean isSphere()

true if the ellipsoid is degenerate and is actually a sphere. The sphere is completely defined by the semi-major axis, which is the radius of the sphere.

Returns:

true if the ellipsoid is degenerate and is actually a sphere.

UML identifier (conditional attribute): secondDefiningParameter.isSphere