 All Superinterfaces:
IdentifiedObject
 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:
 1.0
 Departure from OGC/ISO abstract specification:
Departure due to constraint of the Java language
ISO 19111 defines the union namedsecondDefiningParameter
as being eithersemiMinorAxis
orinverseFlattening
. Theunion
construct (defined in some languages like C/C++) does not exist in Java. GeoAPI changed the interface to require both ellipsoidal parameters (in addition to thesemiMajorAxis
parameter which is mandatory in any case), as was done in OGC 01009. However, implementors could readily permit users to only provide one of the two parameters by creating a class which calculates the second parameter from the first. For precision, GeoAPI imports theisIvfDefinitive
attribute from OGC 01009 to enable the user to establish which of the two parameters was used to define the instance.

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

Method Summary
Modifier and TypeMethodDescriptionUnit<Length>
Returns the linear unit of the semimajor and semiminor axis values.double
Returns the value of the inverse of the flattening constant.double
Length of the semimajor axis of the ellipsoid.double
Length of the semiminor axis of the ellipsoid.boolean
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 Details

getAxisUnit
Returns the linear unit of the semimajor and semiminor axis values. Returns:
 The axis linear unit.

getSemiMajorAxis
@UML(identifier="semiMajorAxis", obligation=MANDATORY, specification=ISO_19111) double getSemiMajorAxis()Length of the semimajor axis of the ellipsoid. This is the equatorial radius in axis linear unit. Returns:
 Length of semimajor axis.
 Unit:
 Length

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.
 Unit:
 Length

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 formula ivf = r_{e}/(r_{e}r_{p}). For perfect spheres (i.e. ifisSphere()
returnstrue
), thePOSITIVE_INFINITY
value is used. Returns:
 The inverse flattening value.
 Unit:
 Scale

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.
