Class EllipsoidToCentricTransform
Object
FormattableObject
AbstractMathTransform
EllipsoidToCentricTransform
- All Implemented Interfaces:
Serializable
,Parameterized
,LenientComparable
,Printable
,MathTransform
Transform from two- or three- dimensional ellipsoidal coordinates to geocentric or planetocentric coordinates.
This transform is usually (but not necessarily) part of a conversion from
geographic to
geocentric coordinates.
Each input coordinate tuple is expected to contain:
- longitude (λ) relative to the prime meridian (usually Greenwich),
- latitude (φ),
- optionally height above the ellipsoid (h).
- In the Cartesian case:
- distance from Earth center on the X axis (toward the intersection of prime meridian and equator),
- distance from Earth center on the Y axis (toward the intersection of 90°E meridian and equator),
- distance from Earth center on the Z axis (toward North pole).
- In the spherical case:
- spherical longitude (same as the geodetic longitude given in input),
- spherical latitude (slightly different than the geodetic latitude),
- distance from Earth center (radius).
MathTransform
has been created:
EllipsoidToCentricTransform
instances created directly by the constructor expect (λ,φ) values in radians and compute (X,Y,Z) values in units of an ellipsoid having a semi-major axis length of 1.- Transforms created by the
createGeodeticConversion(…)
static method expect (λ,φ) values in degrees and compute (X,Y,Z) values in units of the ellipsoid axes (usually metres).
- Since:
- 0.7
- See Also:
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic enum
Whether the output coordinate system is Cartesian or spherical. -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected final double
The square of the eccentricity.protected final boolean
Whether the ellipsoidal coordinate tuples include an ellipsoidal height (3D case). -
Constructor Summary
ConstructorsConstructorDescriptionEllipsoidToCentricTransform
(double semiMajor, double semiMinor, Unit<Length> unit, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) Deprecated, for removal: This API element is subject to removal in a future version.EllipsoidToCentricTransform
(Ellipsoid source, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) Creates a transform from angles in radians on an ellipsoid having a semi-major axis length of 1. -
Method Summary
Modifier and TypeMethodDescriptionstatic MathTransform
createGeodeticConversion
(MathTransformFactory factory, double semiMajor, double semiMinor, Unit<Length> unit, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) Deprecated, for removal: This API element is subject to removal in a future version.static MathTransform
createGeodeticConversion
(MathTransformFactory factory, Ellipsoid ellipsoid, boolean withHeight) Creates a transform from geographic to Cartesian geocentric coordinates (convenience method).static MathTransform
createGeodeticConversion
(MathTransformFactory factory, Ellipsoid source, boolean withHeight, EllipsoidToCentricTransform.TargetType target) Creates a transform from geographic to geocentric coordinates.derivative
(DirectPosition point) Computes the derivative at the given location.protected ContextualParameters
Returns the parameters used for creating the complete conversion.Returns a description of the internal parameters of thisEllipsoidToCentricTransform
transform.Returns a copy of internal parameter values of thisEllipsoidToCentricTransform
transform.final int
Gets the dimension of input points, which is 2 or 3.final int
Gets the dimension of output points, which is 3.Returns whether the target coordinate system is Cartesian or spherical.inverse()
Returns the inverse of this transform.protected void
inverseTransform
(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) Converts Cartesian coordinates (X,Y,Z) to ellipsoidal coordinates (λ,φ) or (λ,φ,h).transform
(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) Converts the (λ,φ) or (λ,φ,h) geodetic coordinates to to (X,Y,Z) geocentric coordinates, and optionally returns the derivative at that location.void
transform
(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) Converts the (λ,φ) or (λ,φ,h) geodetic coordinates to to (X,Y,Z) geocentric coordinates.protected void
tryConcatenate
(TransformJoiner context) If this transform expects three-dimensional inputs, and if the transform just before this one unconditionally sets the height to zero, then replaces this transform by a two-dimensional one.Methods inherited from class AbstractMathTransform
equals, formatTo, getDomain, hashCode, isIdentity, transform, transform, transform, transform, tryConcatenate
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 MathTransform
toWKT
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Field Details
-
eccentricitySquared
protected final double eccentricitySquaredThe square of the eccentricity. This is defined as ℯ² = (a²-b²)/a² where a is the semi-major axis length and b is the semi-minor axis length. -
withHeight
protected final boolean withHeightWhether the ellipsoidal coordinate tuples include an ellipsoidal height (3D case). Iffalse
, then the input coordinate tuples are expected to be two-dimensional and the ellipsoidal height is assumed to be 0.- Since:
- 1.5
- See Also:
-
-
Constructor Details
-
EllipsoidToCentricTransform
@Deprecated(since="1.5", forRemoval=true) public EllipsoidToCentricTransform(double semiMajor, double semiMinor, Unit<Length> unit, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) Deprecated, for removal: This API element is subject to removal in a future version.Creates a transform from angles in radians on an ellipsoid having a semi-major axis length of 1.- Parameters:
semiMajor
- the semi-major axis length.semiMinor
- the semi-minor axis length.unit
- the unit of measurement for the semi-axes and the ellipsoidal height.withHeight
-true
if source geographic coordinates include an ellipsoidal height (i.e. are 3-D), orfalse
if they are only 2-D.csType
- whether the target coordinate system shall be Cartesian or spherical.
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EllipsoidToCentricTransform
public EllipsoidToCentricTransform(Ellipsoid source, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) Creates a transform from angles in radians on an ellipsoid having a semi-major axis length of 1. While a full ellipsoid is specified to this constructor, only the ratio of axis lengths is used.EllipsoidToCentricTransform
instances expect input coordinate tuples as below:- longitudes in radians (unit constraint is relaxed in the spherical case),
- latitudes in radians,
- optionally heights above the ellipsoid, in units of an ellipsoid having a semi-major axis length of 1.
- distance from Earth center on the X axis (toward the intersection of prime meridian and equator),
- distance from Earth center on the Y axis (toward the intersection of 90°E meridian and equator),
- distance from Earth center on the Z axis (toward North pole).
Geographic to geocentric conversions
For converting geographic coordinates to geocentric coordinates,EllipsoidToCentricTransform
instances need to be concatenated with the following affine transforms:- Normalization before
EllipsoidToCentricTransform
:- Conversion of (λ,φ) from degrees to radians
- Division of (h) by the semi-major axis length
- Denormalization after
EllipsoidToCentricTransform
:- Multiplication of (X,Y,Z) by the semi-major axis length
EllipsoidToCentricTransform
construction, the full conversion chain including the above affine transforms can be created bygetContextualParameters().completeTransform(factory, this)}
.- Parameters:
source
- the ellipsoid of the geographic CRS of the coordinates to convert.withHeight
-true
if source geographic coordinates include an ellipsoidal height (i.e. are 3-D), orfalse
if they are only 2-D.csType
- whether the target coordinate system shall be Cartesian or spherical.- Since:
- 1.5
- See Also:
-
-
Method Details
-
createGeodeticConversion
@Deprecated(since="1.5", forRemoval=true) public static MathTransform createGeodeticConversion(MathTransformFactory factory, double semiMajor, double semiMinor, Unit<Length> unit, boolean withHeight, EllipsoidToCentricTransform.TargetType csType) throws FactoryException Deprecated, for removal: This API element is subject to removal in a future version.Creates a transform from geographic to geocentric coordinates.- Parameters:
factory
- the factory to use for creating and concatenating the affine transforms.semiMajor
- the semi-major axis length.semiMinor
- the semi-minor axis length.unit
- the unit of measurement for the semi-axes and the ellipsoidal height.withHeight
-true
if source geographic coordinates include an ellipsoidal height (i.e. are 3-D), orfalse
if they are only 2-D.csType
- whether the target coordinate system shall be Cartesian or spherical.- Returns:
- the conversion from geographic to geocentric coordinates.
- Throws:
FactoryException
- if an error occurred while creating a transform.
-
createGeodeticConversion
public static MathTransform createGeodeticConversion(MathTransformFactory factory, Ellipsoid source, boolean withHeight, EllipsoidToCentricTransform.TargetType target) throws FactoryException Creates a transform from geographic to geocentric coordinates. This factory method combines theEllipsoidToCentricTransform
instance with the steps needed for converting degrees to radians and expressing the results in units of the given ellipsoid.Input coordinates are expected to contain:
- longitudes in degrees (unit constraint is relaxed in the spherical case),
- latitudes in degrees,
- optionally heights above the ellipsoid, in units of the ellipsoid axis (usually metres).
- distance from Earth center on the X axis (toward the intersection of prime meridian and equator),
- distance from Earth center on the Y axis (toward the intersection of 90°E meridian and equator),
- distance from Earth center on the Z axis (toward North pole).
- Parameters:
factory
- the factory to use for creating and concatenating the affine transforms.source
- the ellipsoid of the geographic CRS of the coordinates to convert.withHeight
-true
if source geographic coordinates include an ellipsoidal height (i.e. are 3-D), orfalse
if they are only 2-D.target
- whether the target coordinate system shall be Cartesian or spherical.- Returns:
- the conversion from geographic to geocentric coordinates.
- Throws:
FactoryException
- if an error occurred while creating a transform.- Since:
- 1.5
-
createGeodeticConversion
public static MathTransform createGeodeticConversion(MathTransformFactory factory, Ellipsoid ellipsoid, boolean withHeight) throws FactoryException Creates a transform from geographic to Cartesian geocentric coordinates (convenience method). This is a shortcut for the above method with a default parameter value orEllipsoidToCentricTransform.TargetType.CARTESIAN
. The Cartesian coordinate system is the most usual target of theGeographic/geocentric conversions
(EPSG:9602) operation and is the target assumed by Well Known Text (WKT).- Parameters:
factory
- the factory to use for creating and concatenating the affine transforms.ellipsoid
- the semi-major and semi-minor axis lengths with their unit of measurement.withHeight
-true
if source geographic coordinates include an ellipsoidal height (i.e. are 3-D), orfalse
if they are only 2-D.- Returns:
- the conversion from geographic to Cartesian geocentric coordinates.
- Throws:
FactoryException
- if an error occurred while creating a transform.
-
getContextualParameters
Returns the parameters used for creating the complete conversion. Those parameters describe a sequence of normalize →this
→ denormalize transforms, not including axis swapping. Those parameters are used for formatting Well Known Text (WKT) and error messages.- Overrides:
getContextualParameters
in classAbstractMathTransform
- Returns:
- the parameter values for the normalize →
this
→ denormalize chain of transforms.
-
getParameterValues
Returns a copy of internal parameter values of thisEllipsoidToCentricTransform
transform. The returned group contains parameter values for the number of dimensions, the eccentricity and the target type (Cartesian or spherical).Usage note
This method is mostly for debugging purposes since the isolation of non-linear parameters in this class is highly implementation dependent. Most GIS applications will instead be interested in the contextual parameters.- Specified by:
getParameterValues
in interfaceParameterized
- Overrides:
getParameterValues
in classAbstractMathTransform
- Returns:
- a copy of the internal parameter values for this transform.
- See Also:
-
getParameterDescriptors
Returns a description of the internal parameters of thisEllipsoidToCentricTransform
transform. The returned group contains parameter descriptors for the number of dimensions and the eccentricity.- Specified by:
getParameterDescriptors
in interfaceParameterized
- Overrides:
getParameterDescriptors
in classAbstractMathTransform
- Returns:
- a description of the internal parameters.
- See Also:
-
getSourceDimensions
public final int getSourceDimensions()Gets the dimension of input points, which is 2 or 3.- Specified by:
getSourceDimensions
in interfaceMathTransform
- Specified by:
getSourceDimensions
in classAbstractMathTransform
- Returns:
- 2 or 3.
- See Also:
-
getTargetDimensions
public final int getTargetDimensions()Gets the dimension of output points, which is 3.- Specified by:
getTargetDimensions
in interfaceMathTransform
- Specified by:
getTargetDimensions
in classAbstractMathTransform
- Returns:
- always 3.
- See Also:
-
getTargetType
Returns whether the target coordinate system is Cartesian or spherical.- Returns:
- whether the target coordinate system is Cartesian or spherical.
-
derivative
Computes the derivative at the given location. This method relaxes a little bit theMathTransform
contract by accepting two- or three-dimensional points even if the number of dimensions does not match thegetSourceDimensions()
value.Rational
That flexibility on the number of dimensions is required for calculation of inverse transform derivative, because that calculation needs to inverse a square matrix with all terms in it before to drop the last row in the two-dimensional case.- Specified by:
derivative
in interfaceMathTransform
- Overrides:
derivative
in classAbstractMathTransform
- Parameters:
point
- the position where to evaluate the derivative.- Returns:
- the derivative at the specified point (never
null
). - Throws:
TransformException
- if the derivative cannot be evaluated at the specified point.
-
transform
public Matrix transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) throws TransformException Converts the (λ,φ) or (λ,φ,h) geodetic coordinates to to (X,Y,Z) geocentric coordinates, and optionally returns the derivative at that location.- Specified by:
transform
in classAbstractMathTransform
- Parameters:
srcPts
- the array containing the source coordinates (cannot benull
).srcOff
- the offset to the point to be transformed in the source array.dstPts
- the array into which the transformed coordinates is returned. May be the same assrcPts
. May benull
if only the derivative matrix is desired.dstOff
- the offset to the location of the transformed point that is stored in the destination array.derivate
-true
for computing the derivative, orfalse
if not needed.- Returns:
- the matrix of the transform derivative at the given source position,
or
null
if thederivate
argument isfalse
. - Throws:
TransformException
- if the point cannot be transformed or if a problem occurred while calculating the derivative.- See Also:
-
transform
public void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws TransformException Converts the (λ,φ) or (λ,φ,h) geodetic coordinates to to (X,Y,Z) geocentric coordinates. This method performs the same conversion astransform(double[], int, double[], int, boolean)
, but the formulas are repeated here for performance reasons.- Specified by:
transform
in interfaceMathTransform
- Overrides:
transform
in classAbstractMathTransform
- Parameters:
srcPts
- the array containing the source point coordinates.srcOff
- the offset to the first point to be transformed in the source array.dstPts
- the array into which the transformed point coordinates are returned. May be the same assrcPts
.dstOff
- the offset to the location of the first transformed point that is stored in the destination array.numPts
- the number of point objects to be transformed.- Throws:
TransformException
- if a point cannot be transformed.
-
inverseTransform
protected void inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws TransformException Converts Cartesian coordinates (X,Y,Z) to ellipsoidal coordinates (λ,φ) or (λ,φ,h). This method is invoked by the transform returned byinverse()
.- Parameters:
srcPts
- the array containing the source point coordinates.srcOff
- the offset to the first point to be transformed in the source array.dstPts
- the array into which the transformed point coordinates are returned. May be the same assrcPts
.dstOff
- the offset to the location of the first transformed point that is stored in the destination array.numPts
- the number of point objects to be transformed.- Throws:
TransformException
- if the calculation does not converge.
-
inverse
Returns the inverse of this transform. The default implementation returns a transform that will delegate its work toinverseTransform(double[], int, double[], int, int)
.- Specified by:
inverse
in interfaceMathTransform
- Overrides:
inverse
in classAbstractMathTransform
- Returns:
- the conversion from geocentric or planetocentric to ellipsoidal coordinates.
-
tryConcatenate
If this transform expects three-dimensional inputs, and if the transform just before this one unconditionally sets the height to zero, then replaces this transform by a two-dimensional one. The intent is to handle the following sequence of operations defined in the EPSG database:- Inverse of Geographic 3D to 2D conversion (EPSG:9659)
- Geographic/geocentric conversions (EPSG:9602)
EllipsoidToCentricTransform
instance allow the following optimizations:- Avoid computation of h value.
- Allow use of the more efficient
AffineTransform
before this transform instead of a transform based on a matrix of size 4×3.
- Overrides:
tryConcatenate
in classAbstractMathTransform
- Parameters:
context
- information about the neighbor transforms, and the object where to set the result.- Throws:
FactoryException
- if an error occurred while combining the transforms.- See Also:
-
EllipsoidToCentricTransform(Ellipsoid, boolean, TargetType)
.