Object
FormattableObject
AbstractIdentifiedObject
DefaultEllipsoid
- All Implemented Interfaces:
Serializable
,Formattable
,Deprecable
,LenientComparable
,Ellipsoid
,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:
- semi-major axis and inverse flattening, or
- semi-major axis and semi-minor axis.
Creating new ellipsoid instances
New instances can be created either directly by specifying all information to a factory method (choices 3 and 4 below), or indirectly by specifying the identifier of an entry in a database (choices 1 and 2 below). In particular, the EPSG repository provides definitions for many ellipsoids, and Apache SIS provides convenience shortcuts for some of them.Choice 1 in the following list is the easiest but most restrictive way to get an ellipsoid. The other choices provide more freedom. Each choice delegates its work to the subsequent items (in the default configuration), so this list can be seen as top to bottom API.
- Create an
Ellipsoid
from one of the static convenience shortcuts listed inCommonCRS.ellipsoid()
. - Create an
Ellipsoid
from an identifier in a database by invokingDatumAuthorityFactory.createEllipsoid(String)
. - Create an
Ellipsoid
by invoking theDatumFactory.createEllipsoid(…)
orcreateFlattenedSphere(…)
method (implemented for example byGeodeticObjectFactory
). - Create a
DefaultEllipsoid
by invoking thecreateEllipsoid(…)
orcreateFlattenedSphere(…)
static methods defined in this class.
Ellipsoid e = CommonCRS.WGS84.ellipsoid();
Immutability and thread safety
This class is immutable and thus thread-safe if the property values (not necessarily the map itself) given to the constructors are also immutable. Unless otherwise noted in the javadoc, this condition holds if all components were created using only SIS factories and static constants.- Since:
- 0.4
- See Also:
-
Field Summary
Fields inherited from class AbstractIdentifiedObject
DEPRECATED_KEY, LOCALE_KEY
Fields inherited from interface IdentifiedObject
ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY
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Constructor Summary
ModifierConstructorDescriptionprotected
DefaultEllipsoid
(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, double inverseFlattening, boolean ivfDefinitive, Unit<Length> unit) Creates a new ellipsoid using the specified axis length.protected
DefaultEllipsoid
(Ellipsoid ellipsoid) Creates a new ellipsoid with the same values than the specified one. -
Method Summary
Modifier and TypeMethodDescriptionstatic DefaultEllipsoid
castOrCopy
(Ellipsoid object) Returns a SIS ellipsoid implementation with the same values than the given arbitrary implementation.protected long
Invoked byhashCode()
for computing the hash code when first needed.static DefaultEllipsoid
createEllipsoid
(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, Unit<Length> unit) Creates a new ellipsoid using the specified properties and axis length.static DefaultEllipsoid
createFlattenedSphere
(Map<String, ?> properties, double semiMajorAxis, double inverseFlattening, Unit<Length> unit) Creates a new ellipsoid using the specified properties, axis length and inverse flattening value.boolean
equals
(Object object, ComparisonMode mode) Compares this ellipsoid with the specified object for equality.double
flatteningDifference
(Ellipsoid other) Returns the difference between the flattening factor of two ellipsoids.protected String
Formats this ellipsoid as a Well Known TextEllipsoid[…]
element.double
Returns the radius of a hypothetical sphere having the same surface than this ellipsoid.Returns the linear unit of the semi-major and semi-minor axis values.double
The ratio of the distance between the center and a focus of the ellipse to the length of its semi-major axis.double
Returns the square of theeccentricity
value.double
getGeocentricRadius
(double φ) Returns the geocentric radius at the given latitude.Returns the GeoAPI interface implemented by this class.double
Returns the value of the inverse of the flattening constant.double
getRadius
(double φ) Deprecated.double
Length of the semi-major axis of the ellipsoid.double
Length of the semi-minor axis of the ellipsoid.boolean
Indicates if the inverse flattening is definitive for this ellipsoid.boolean
true
if the ellipsoid is degenerate and is actually a sphere.double
Returns the difference between the semi-major axis length of two ellipsoids.Methods inherited from class AbstractIdentifiedObject
castOrCopy, equals, formatTo, getAlias, getDescription, getDomains, getIdentifiers, getName, getRemarks, hashCode, isDeprecated, isHeuristicMatchForName
Methods inherited from class FormattableObject
print, toString, toString, toWKT
Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface IdentifiedObject
getAlias, getIdentifiers, getName, getRemarks, toWKT
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Constructor Details
-
DefaultEllipsoid
protected DefaultEllipsoid(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, double inverseFlattening, boolean ivfDefinitive, Unit<Length> unit) Creates a new ellipsoid using the specified axis length. The properties map is given unchanged to the super-class constructor. The following table is a reminder of main (not all) properties:Recognized properties (non exhaustive list) Property name Value type Returned by "name" ReferenceIdentifier
orString
AbstractIdentifiedObject.getName()
"alias" GenericName
orCharSequence
(optionally as array)AbstractIdentifiedObject.getAlias()
"identifiers" ReferenceIdentifier
(optionally as array)AbstractIdentifiedObject.getIdentifiers()
"remarks" InternationalString
orString
AbstractIdentifiedObject.getRemarks()
- Parameters:
properties
- the properties to be given to the identified object.semiMajorAxis
- the equatorial radius.semiMinorAxis
- the polar radius.inverseFlattening
- the inverse of the flattening value.ivfDefinitive
-true
if the inverse flattening is definitive.unit
- the units of the semi-major and semi-minor axis values.- See Also:
-
DefaultEllipsoid
Creates a new ellipsoid with the same values than the specified one. This copy constructor provides a way to convert an arbitrary implementation into a SIS one or a user-defined one (as a subclass), usually in order to leverage some implementation-specific API.This constructor performs a shallow copy, i.e. the properties are not cloned.
- Parameters:
ellipsoid
- the ellipsoid to copy.- See Also:
-
-
Method Details
-
createEllipsoid
public static DefaultEllipsoid createEllipsoid(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, Unit<Length> unit) Creates a new ellipsoid using the specified properties and axis length. The properties map is given unchanged to the super-class constructor.- Parameters:
properties
- the properties to be given to the identified object.semiMajorAxis
- the equatorial radius in the given unit.semiMinorAxis
- the polar radius in the given unit.unit
- the units of the semi-major and semi-minor axis values.- Returns:
- an ellipsoid with the given axis length.
- See Also:
-
createFlattenedSphere
public static DefaultEllipsoid createFlattenedSphere(Map<String, ?> properties, double semiMajorAxis, double inverseFlattening, Unit<Length> unit) Creates a new ellipsoid using the specified properties, axis length and inverse flattening value. The properties map is given unchanged to the super-class constructor.- Parameters:
properties
- the properties to be given to the identified object.semiMajorAxis
- the equatorial radius in the given unit.inverseFlattening
- the inverse flattening value.unit
- the units of the semi-major and semi-minor axis values.- Returns:
- an ellipsoid with the given axis length.
- See Also:
-
castOrCopy
Returns a SIS ellipsoid implementation with the same values than the given arbitrary implementation. If the given object isnull
, then this method returnsnull
. Otherwise if the given object is already a SIS implementation, then the given object is returned unchanged. Otherwise a new SIS implementation is created and initialized to the attribute values of the given object.- Parameters:
object
- the object to get as a SIS implementation, ornull
if none.- Returns:
- a SIS implementation containing the values of the given object (may be the
given object itself), or
null
if the argument was null.
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getInterface
Returns the GeoAPI interface implemented by this class. The SIS implementation returnsEllipsoid.class
.Note for implementers
Subclasses usually do not need to override this method since GeoAPI does not defineEllipsoid
sub-interface. Overriding possibility is left mostly for implementers who wish to extend GeoAPI with their own set of interfaces.- Overrides:
getInterface
in classAbstractIdentifiedObject
- Returns:
Ellipsoid.class
or a user-defined sub-interface.
-
getAxisUnit
Returns the linear unit of the semi-major and semi-minor axis values.- Specified by:
getAxisUnit
in interfaceEllipsoid
- Returns:
- the axis linear unit.
-
getSemiMajorAxis
public double getSemiMajorAxis()Length of the semi-major axis of the ellipsoid. This is the equatorial radius in axis linear unit.- Specified by:
getSemiMajorAxis
in interfaceEllipsoid
- Returns:
- length of semi-major axis.
-
getSemiMinorAxis
public double getSemiMinorAxis()Length of the semi-minor axis of the ellipsoid. This is the polar radius in axis linear unit.- Specified by:
getSemiMinorAxis
in interfaceEllipsoid
- Returns:
- length of semi-minor axis.
-
getAuthalicRadius
public double getAuthalicRadius()Returns the radius of a hypothetical sphere having the same surface than this ellipsoid. The radius is expressed in axis linear unit.- Returns:
- the radius of a sphere having the same surface than this ellipsoid.
- See Also:
-
getGeocentricRadius
public double getGeocentricRadius(double φ) Returns the geocentric radius at the given latitude. Special cases:- If φ = 0°, then this is the same value as
getSemiMajorAxis()
. - If φ = ±90°, then this is the same value as
getSemiMinorAxis()
. - If φ is NaN, then this method returns NaN.
- Parameters:
φ
- latitude in degrees, from -90° to +90° inclusive.- Returns:
- geocentric radius at latitude φ°.
- Since:
- 1.4
- If φ = 0°, then this is the same value as
-
getRadius
Deprecated.RenamedgetGeocentricRadius(double)
.- Parameters:
φ
- latitude in degrees, from -90° to +90° inclusive.- Returns:
- geocentric radius at the given latitude.
- Since:
- 1.3
-
getEccentricity
public double getEccentricity()The ratio of the distance between the center and a focus of the ellipse to the length of its semi-major axis. The eccentricity can alternately be computed from the equation: ℯ = √(2f - f²) where f is the flattening factor (not inverse).- Returns:
- ℯ, the eccentricity of this ellipsoid.
-
getEccentricitySquared
public double getEccentricitySquared()Returns the square of theeccentricity
value. This convenience method is provided because ℯ² is frequently used in coordinate operations, actually more often than ℯ. This convenience method avoids the cost of computing the square root when not needed.- Returns:
- ℯ², the square of the eccentricity value.
- Since:
- 0.7
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getInverseFlattening
public double getInverseFlattening()Returns the value of the inverse of the flattening constant. Flattening is a value used to indicate how closely an ellipsoid approaches a spherical shape. The inverse flattening is related to the equatorial/polar radius by the formula:ivf = re / (re - rp).
For perfect spheres (i.e. ifisSphere()
returnstrue
), theDouble.POSITIVE_INFINITY
value is used.- Specified by:
getInverseFlattening
in interfaceEllipsoid
- Returns:
- the inverse flattening value.
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isIvfDefinitive
public 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.- Specified by:
isIvfDefinitive
in interfaceEllipsoid
- Returns:
true
if the inverse flattening is definitive, orfalse
if the polar radius is definitive.
-
isSphere
public 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. -
semiMajorAxisDifference
Returns the difference between the semi-major axis length of two ellipsoids. If the two ellipsoid does not use the same unit of measurement, than the axis length of the other ellipsoid is converted into the units of this ellipsoid axis.Example
WGS84.semiMajorAxisDifference(ED50)
returns 251 metres. This information is a parameter of Molodensky transformations.- Parameters:
other
- the other ellipsoid from which to get semi-major axis length difference.- Returns:
- (other ellipsoid semi-major axis) - (this ellipsoid semi-major axis).
- Since:
- 0.7
-
flatteningDifference
Returns the difference between the flattening factor of two ellipsoids. This method returns 0 if the two ellipsoids are equal.Example
WGS84.flatteningDifference(ED50)
returns approximately 1.41927E-05. This information is a parameter of Molodensky transformations.- Parameters:
other
- the other ellipsoid from which to get flattening difference.- Returns:
- (other ellipsoid flattening) - (this ellipsoid flattening).
- Since:
- 0.7
-
equals
Compares this ellipsoid with the specified object for equality.- Specified by:
equals
in interfaceLenientComparable
- Overrides:
equals
in classAbstractIdentifiedObject
- Parameters:
object
- the object to compare tothis
.mode
-STRICT
for performing a strict comparison, orIGNORE_METADATA
for comparing only properties relevant to coordinate transformations.- Returns:
true
if both objects are equal.- See Also:
-
computeHashCode
protected long computeHashCode()Invoked byhashCode()
for computing the hash code when first needed. SeeAbstractIdentifiedObject.computeHashCode()
for more information.- Overrides:
computeHashCode
in classAbstractIdentifiedObject
- Returns:
- the hash code value. This value may change in any future Apache SIS version.
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formatTo
Formats this ellipsoid as a Well Known TextEllipsoid[…]
element.- Overrides:
formatTo
in classAbstractIdentifiedObject
- Parameters:
formatter
- the formatter where to format the inner content of this WKT element.- Returns:
"Ellipsoid"
(WKT 2) or"Spheroid"
(WKT 1).- See Also:
-
getGeocentricRadius(double)
.