Package org.apache.sis.referencing.datum
Class DefaultEllipsoid
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 Ellipsoidfrom one of the static convenience shortcuts listed inCommonCRS.ellipsoid().
- Create an Ellipsoidfrom an identifier in a database by invokingDatumAuthorityFactory.createEllipsoid(String).
- Create an Ellipsoidby invoking theDatumFactory.createEllipsoid(…)orcreateFlattenedSphere(…)method (implemented for example byGeodeticObjectFactory).
- Create a DefaultEllipsoidby 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:
Defined in the sis-referencing module
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Field SummaryFields inherited from class AbstractIdentifiedObjectDEPRECATED_KEY, LOCALE_KEYFields inherited from interface IdentifiedObjectALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY
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Constructor SummaryConstructorsModifierConstructorDescriptionprotectedDefaultEllipsoid(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, double inverseFlattening, boolean ivfDefinitive, Unit<Length> unit) Creates a new ellipsoid using the specified axis length.protectedDefaultEllipsoid(Ellipsoid ellipsoid) Creates a new ellipsoid with the same values than the specified one.
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Method SummaryModifier and TypeMethodDescriptionstatic DefaultEllipsoidcastOrCopy(Ellipsoid object) Returns a SIS ellipsoid implementation with the same values than the given arbitrary implementation.protected longInvoked byhashCode()for computing the hash code when first needed.static DefaultEllipsoidcreateEllipsoid(Map<String, ?> properties, double semiMajorAxis, double semiMinorAxis, Unit<Length> unit) Creates a new ellipsoid using the specified properties and axis length.static DefaultEllipsoidcreateFlattenedSphere(Map<String, ?> properties, double semiMajorAxis, double inverseFlattening, Unit<Length> unit) Creates a new ellipsoid using the specified properties, axis length and inverse flattening value.booleanequals(Object object, ComparisonMode mode) Compares this ellipsoid with the specified object for equality.doubleflatteningDifference(Ellipsoid other) Returns the difference between the flattening factor of two ellipsoids.protected StringFormats this ellipsoid as a Well Known TextEllipsoid[…]element.doubleReturns 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.doubleThe ratio of the distance between the center and a focus of the ellipse to the length of its semi-major axis.doubleReturns the square of theeccentricityvalue.Returns the GeoAPI interface implemented by this class.doubleReturns the value of the inverse of the flattening constant.doublegetRadius(double φ) Returns the radius at the given latitude.doubleLength of the semi-major axis of the ellipsoid.doubleLength of the semi-minor axis of the ellipsoid.booleanIndicates if the inverse flattening is definitive for this ellipsoid.booleantrueif the ellipsoid is degenerate and is actually a sphere.doubleReturns the difference between the semi-major axis length of two ellipsoids.Methods inherited from class AbstractIdentifiedObjectcastOrCopy, equals, formatTo, getAlias, getDescription, getIdentifiers, getName, getRemarks, hashCode, isDeprecated, isHeuristicMatchForNameMethods inherited from class FormattableObjectprint, toString, toString, toWKTMethods inherited from class Objectclone, finalize, getClass, notify, notifyAll, wait, wait, waitMethods inherited from interface IdentifiedObjectgetAlias, getIdentifiers, getName, getRemarks, toWKT
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Constructor Details- 
DefaultEllipsoidprotected 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" ReferenceIdentifierorStringAbstractIdentifiedObject.getName()"alias" GenericNameorCharSequence(optionally as array)AbstractIdentifiedObject.getAlias()"identifiers" ReferenceIdentifier(optionally as array)AbstractIdentifiedObject.getIdentifiers()"remarks" InternationalStringorStringAbstractIdentifiedObject.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-- trueif the inverse flattening is definitive.
- unit- the units of the semi-major and semi-minor axis values.
- See Also:
 
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DefaultEllipsoidCreates 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:
 
 
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Method Details- 
createEllipsoidpublic 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:
 
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createFlattenedSpherepublic 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:
 
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castOrCopyReturns 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, or- nullif none.
- Returns:
- a SIS implementation containing the values of the given object (may be the
         given object itself), or nullif the argument was null.
 
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getInterfaceReturns 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 defineEllipsoidsub-interface. Overriding possibility is left mostly for implementers who wish to extend GeoAPI with their own set of interfaces.- Overrides:
- getInterfacein class- AbstractIdentifiedObject
- Returns:
- Ellipsoid.classor a user-defined sub-interface.
 
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getAxisUnitReturns the linear unit of the semi-major and semi-minor axis values.- Specified by:
- getAxisUnitin interface- Ellipsoid
- Returns:
- the axis linear unit.
 
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getSemiMajorAxispublic double getSemiMajorAxis()Length of the semi-major axis of the ellipsoid. This is the equatorial radius in axis linear unit.- Specified by:
- getSemiMajorAxisin interface- Ellipsoid
- Returns:
- length of semi-major axis.
 
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getSemiMinorAxispublic double getSemiMinorAxis()Length of the semi-minor axis of the ellipsoid. This is the polar radius in axis linear unit.- Specified by:
- getSemiMinorAxisin interface- Ellipsoid
- Returns:
- length of semi-minor axis.
 
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getAuthalicRadiuspublic 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:
 
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getRadiuspublic double getRadius(double φ) Returns the 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:
- radius at the given latitude.
- Since:
- 1.3
 
- If φ =   0°, then this is the same value as 
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getEccentricitypublic 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.
 
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getEccentricitySquaredpublic double getEccentricitySquared()Returns the square of theeccentricityvalue.Purpose: 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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getInverseFlatteningpublic 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_INFINITYvalue is used.- Specified by:
- getInverseFlatteningin interface- Ellipsoid
- Returns:
- the inverse flattening value.
 
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isIvfDefinitivepublic 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:
- isIvfDefinitivein interface- Ellipsoid
- Returns:
- trueif the inverse flattening is definitive, or- falseif the polar radius is definitive.
 
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isSpherepublic boolean isSphere()trueif 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.
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semiMajorAxisDifferenceReturns 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
 
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flatteningDifferenceReturns 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
 
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equalsCompares this ellipsoid with the specified object for equality.- Specified by:
- equalsin interface- LenientComparable
- Overrides:
- equalsin class- AbstractIdentifiedObject
- Parameters:
- object- the object to compare to- this.
- mode-- STRICTfor performing a strict comparison, or- IGNORE_METADATAfor comparing only properties relevant to coordinate transformations.
- Returns:
- trueif both objects are equal.
- See Also:
 
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computeHashCodeprotected long computeHashCode()Invoked byhashCode()for computing the hash code when first needed. SeeAbstractIdentifiedObject.computeHashCode()for more information.- Overrides:
- computeHashCodein class- AbstractIdentifiedObject
- Returns:
- the hash code value. This value may change in any future Apache SIS version.
 
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formatToFormats this ellipsoid as a Well Known TextEllipsoid[…]element.- Overrides:
- formatToin class- AbstractIdentifiedObject
- Parameters:
- formatter- the formatter where to format the inner content of this WKT element.
- Returns:
- "Ellipsoid"(WKT 2) or- "Spheroid"(WKT 1).
- See Also:
 
 
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