Interface Ellipsoid

 All Superinterfaces:
IdentifiedObject
 All Known Implementing Classes:
DefaultEllipsoid
public interface Ellipsoid extends IdentifiedObject
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: semimajor axis and inverse flattening, or
 semimajor axis and semiminor axis.
There is not just one ellipsoid. An ellipsoid is a matter of choice, and therefore many choices are possible. The size and shape of an ellipsoid was traditionally chosen such that the surface of the geoid is matched as closely as possible locally, e.g. in a country. A number of global bestfit ellipsoids are now available. An association of an ellipsoid with the earth is made through the definition of the size and shape of the ellipsoid and the position and orientation of this ellipsoid with respect to the earth. Collectively this choice is captured by the concept of "geodetic datum". A change of size, shape, position or orientation of an ellipsoid will result in a change of geographic coordinates of a point and be described as a different geodetic datum. Conversely geographic coordinates are unambiguous only when associated with a geodetic datum.
 Since:
 GeoAPI 1.0
 Author:
 Martin Desruisseaux (IRD)


Field Summary

Fields inherited from interface IdentifiedObject
ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY


Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description Unit<Length>
getAxisUnit()
Returns the linear unit of the semimajor and semiminor axis values.double
getInverseFlattening()
Returns the value of the inverse of the flattening constant.double
getSemiMajorAxis()
Length of the semimajor axis of the ellipsoid.double
getSemiMinorAxis()
Length of the semiminor 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 IdentifiedObject
getAlias, getIdentifiers, getName, getRemarks, toWKT




Method Detail

getAxisUnit
Unit<Length> getAxisUnit()
Returns the linear unit of the semimajor and semiminor axis values. Returns:
 The axis linear unit.

getSemiMajorAxis
double getSemiMajorAxis()
Length of the semimajor axis of the ellipsoid. This is the equatorial radius in axis linear unit. Returns:
 Length of semimajor axis.

getSemiMinorAxis
@UML(identifier="secondDefiningParameter.semiMinorAxis", obligation=CONDITIONAL, specification=ISO_19111) double getSemiMinorAxis()
Length of the semiminor axis of the ellipsoid. This is the polar radius in axis linear unit. Returns:
 Length of semiminor axis.

getInverseFlattening
@UML(identifier="secondDefiningParameter.inverseFlattening", obligation=CONDITIONAL, specification=ISO_19111) double getInverseFlattening()
Returns the value of the inverse of the flattening constant. The inverse flattening is related to the equatorial/polar radius by the formulaivf = r_{e}/(r_{e}r_{p}).
For perfect spheres (i.e. if
isSphere()
returnstrue
), thePOSITIVE_INFINITY
value is used. Returns:
 The inverse flattening value.

isIvfDefinitive
@UML(identifier="CS_Ellipsoid.isIvfDefinitive", obligation=CONDITIONAL, specification=OGC_01009) 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 floatingpoint rounding errors. Returns:
true
if the inverse flattening is definitive, orfalse
if the polar radius is definitive.

isSphere
@UML(identifier="secondDefiningParameter.isSphere", obligation=CONDITIONAL, specification=ISO_19111) boolean isSphere()
true
if the ellipsoid is degenerate and is actually a sphere. The sphere is completely defined by the semimajor axis, which is the radius of the sphere. Returns:
true
if the ellipsoid is degenerate and is actually a sphere.

