Class InterpolatedMolodenskyTransform
Object
FormattableObject
AbstractMathTransform
DatumShiftTransform
InterpolatedMolodenskyTransform
- All Implemented Interfaces:
Serializable,Parameterized,LenientComparable,MathTransform
Transforms between two geographic CRS by performing geocentric translations interpolated from a grid file, but using
Molodensky approximation. This transformation is conceptually defined as a translation in geocentric coordinates
as performed by
InterpolatedGeocentricTransform, but uses the Molodensy
(non-abridged) approximation for performance reasons.
Errors are less than 3 centimetres for the "France geocentric interpolation" (ESPG:9655).
By comparison, the finest accuracy reported in the grid file for France is 5 centimetres.
Algorithm
This class transforms two- or three- dimensional coordinates from a geographic CRS to another geographic CRS. The changes between source and target coordinates are small (usually less than 400 metres), but vary for every position. Those changes are provided in a datum shift grid, usually loaded from one or two files.Many datum shift grids like NADCON and NTv2 apply the interpolated translations directly on geographic coordinates.
This relatively simple case is handled by InterpolatedTransform.
But in the InterpolatedMolodenskyTransform case, the interpolated translations are rather the
(tX, tY, tZ) parameters of a Molodensky transformation.
- Since:
- 0.7
- See Also:
Defined in the sis-referencing module
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected final doubleThe square of eccentricity of the source ellipsoid.protected final doubleSemi-major axis length (a) of the source ellipsoid.protected final doubleShift along the geocentric X axis (toward prime meridian) in units of the semi-major axis of the source ellipsoid.protected final doubleShift along the geocentric Y axis (toward 90°E) in units of the semi-major axis of the source ellipsoid.protected final doubleShift along the geocentric Z axis (toward north pole) in units of the semi-major axis of the source ellipsoid. -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedInterpolatedMolodenskyTransform(Ellipsoid source, boolean isSource3D, Ellipsoid target, boolean isTarget3D, DatumShiftGrid<Angle, Length> grid) Creates a transform from the specified parameters. -
Method Summary
Modifier and TypeMethodDescriptionprotected intComputes a hash value for this transform.static MathTransformcreateGeodeticTransformation(MathTransformFactory factory, Ellipsoid source, boolean isSource3D, Ellipsoid target, boolean isTarget3D, DatumShiftGrid<Angle, Length> grid) Creates a transformation between two geographic CRS.booleanequals(Object object, ComparisonMode mode) Compares the specified object with this math transform for equality.Returns a description of the internal parameters of thisInterpolatedMolodenskyTransformtransform.Returns a copy of internal parameter values of this transform.final intGets the dimension of input points.final intGets the dimension of output points.inverse()Returns the inverse of this interpolated Molodensky transform.transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) Transforms the (λ,φ) or (λ,φ,h) coordinates between two geographic CRS, and optionally returns the derivative at that location.voidtransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) Transforms the (λ,φ) or (λ,φ,h) coordinates between two geographic CRS.Methods inherited from class DatumShiftTransform
getContextualParametersMethods inherited from class AbstractMathTransform
derivative, equals, formatTo, getDomain, hashCode, isIdentity, transform, transform, transform, transform, tryConcatenateMethods inherited from class FormattableObject
print, toString, toString, toWKTMethods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, waitMethods inherited from interface MathTransform
toWKT
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Field Details
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tX
protected final double tXShift along the geocentric X axis (toward prime meridian) in units of the semi-major axis of the source ellipsoid.- See Also:
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tY
protected final double tYShift along the geocentric Y axis (toward 90°E) in units of the semi-major axis of the source ellipsoid.- See Also:
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tZ
protected final double tZShift along the geocentric Z axis (toward north pole) in units of the semi-major axis of the source ellipsoid.- See Also:
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semiMajor
protected final double semiMajorSemi-major axis length (a) of the source ellipsoid. -
eccentricitySquared
protected final double eccentricitySquaredThe square of eccentricity of the source ellipsoid. This can be computed by ℯ² = (a²-b²)/a² where a is the semi-major axis length and b is the semi-minor axis length.
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Constructor Details
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InterpolatedMolodenskyTransform
protected InterpolatedMolodenskyTransform(Ellipsoid source, boolean isSource3D, Ellipsoid target, boolean isTarget3D, DatumShiftGrid<Angle, Length> grid) Creates a transform from the specified parameters. ThisInterpolatedMolodenskyTransformclass expects coordinate values in the following order and units:- longitudes in radians relative to the prime meridian (usually Greenwich),
- latitudes in radians,
- optionally heights above the ellipsoid, in same units than the source ellipsoid axes.
InterpolatedMolodenskyTransforminstances need to be concatenated with the following affine transforms:- Normalization before
InterpolatedMolodenskyTransform:- Conversion of (λ,φ) from degrees to radians.
- Denormalization after
InterpolatedMolodenskyTransform:- Conversion of (λ,φ) from radians to degrees.
InterpolatedMolodenskyTransformconstruction, the full conversion chain including the above affine transforms can be created byDatumShiftTransform.getContextualParameters().completeTransform(factory, this)}.- Parameters:
source- the source ellipsoid.isSource3D-trueif the source coordinates have a height.target- the target ellipsoid.isTarget3D-trueif the target coordinates have a height.grid- the grid of datum shifts from source to target datum. TheDatumShiftGrid.interpolateInCell(…)method shall compute (ΔX, ΔY, ΔZ) translations from source to target in the unit of source ellipsoid axes.- See Also:
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Method Details
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createGeodeticTransformation
public static MathTransform createGeodeticTransformation(MathTransformFactory factory, Ellipsoid source, boolean isSource3D, Ellipsoid target, boolean isTarget3D, DatumShiftGrid<Angle, Length> grid) throws FactoryExceptionCreates a transformation between two geographic CRS. This factory method combines theInterpolatedMolodenskyTransforminstance with the steps needed for converting values between degrees to radians. The transform works with input and output coordinates in the following units:- longitudes in degrees relative to the prime meridian (usually Greenwich),
- latitudes in degrees,
- optionally heights above the ellipsoid, in same units than the source ellipsoids axes.
gridinstance shall expect geographic coordinates (λ,φ) in radians.- Parameters:
factory- the factory to use for creating the transform.source- the source ellipsoid.isSource3D-trueif the source coordinates have a height.target- the target ellipsoid.isTarget3D-trueif the target coordinates have a height.grid- the grid of datum shifts from source to target datum. TheDatumShiftGrid.interpolateInCell(…)method shall compute (ΔX, ΔY, ΔZ) translations from source to target in the unit of source ellipsoid axes.- Returns:
- the transformation between geographic coordinates in degrees.
- Throws:
FactoryException- if an error occurred while creating a transform.
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transform
public Matrix transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) throws TransformException Transforms the (λ,φ) or (λ,φ,h) coordinates between two geographic CRS, and optionally returns the derivative at that location.- Specified by:
transformin 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 thansrcPts. May benullif only the derivative matrix is desired.dstOff- the offset to the location of the transformed point that is stored in the destination array.derivate-truefor computing the derivative, orfalseif not needed.- Returns:
- the matrix of the transform derivative at the given source position,
or
nullif thederivateargument isfalse. - Throws:
TransformException- if the point cannot be transformed or if a problem occurred while calculating the derivative.- See Also:
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transform
public void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws TransformException Transforms the (λ,φ) or (λ,φ,h) coordinates between two geographic CRS. This method performs the same work than the abovetransform(…)method, but on an arbitrary number of coordinate tuples and without computing derivative.- Specified by:
transformin interfaceMathTransform- Overrides:
transformin 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 thansrcPts.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.
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inverse
Returns the inverse of this interpolated Molodensky transform. The source ellipsoid of the returned transform will be the target ellipsoid of this transform, and conversely.- Specified by:
inversein interfaceMathTransform- Overrides:
inversein classAbstractMathTransform- Returns:
- a transform from the target ellipsoid to the source ellipsoid of this transform.
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getParameterDescriptors
Returns a description of the internal parameters of thisInterpolatedMolodenskyTransformtransform. The returned group contains parameters for the source ellipsoid semi-axis lengths and the differences between source and target ellipsoid parameters.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:
getParameterDescriptorsin interfaceParameterized- Overrides:
getParameterDescriptorsin classAbstractMathTransform- Returns:
- a description of the internal parameters.
- See Also:
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getParameterValues
Returns a copy of internal parameter values of this transform. The returned group contains parameters for the source ellipsoid semi-axis lengths and the differences between source and target ellipsoid parameters.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:
getParameterValuesin interfaceParameterized- Overrides:
getParameterValuesin classDatumShiftTransform- Returns:
- a copy of the internal parameter values for this transform.
- See Also:
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getSourceDimensions
public final int getSourceDimensions()Gets the dimension of input points.- Specified by:
getSourceDimensionsin interfaceMathTransform- Specified by:
getSourceDimensionsin classAbstractMathTransform- Returns:
- the input dimension, which is 2 or 3.
- See Also:
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getTargetDimensions
public final int getTargetDimensions()Gets the dimension of output points.- Specified by:
getTargetDimensionsin interfaceMathTransform- Specified by:
getTargetDimensionsin classAbstractMathTransform- Returns:
- the output dimension, which is 2 or 3.
- See Also:
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computeHashCode
protected int computeHashCode()Computes a hash value for this transform. This method is invoked byAbstractMathTransform.hashCode()when first needed.- Overrides:
computeHashCodein classDatumShiftTransform- Returns:
- the hash code value. This value may change between different execution of the Apache SIS library.
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equals
Compares the specified object with this math transform for equality.- Specified by:
equalsin interfaceLenientComparable- Overrides:
equalsin classDatumShiftTransform- Parameters:
object- the object to compare with this transform.mode- the strictness level of the comparison. Default toSTRICT.- Returns:
trueif the given object is considered equals to this math transform.- See Also:
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