Class LinearTransformBuilder
LinearTransformBuilder(int...)
constructor will be more efficient.
Otherwise a builder created by the LinearTransformBuilder()
constructor will be able to handle
randomly distributed coordinates.
Builders are not thread-safe. Builders can be used only once;
points cannot be added or modified after create(MathTransformFactory)
has been invoked.
The transform coefficients are determined using a least squares estimation method,
with the assumption that source positions are exact and all the uncertainty is in the target positions.
Linearizers
Consider the following situation (commonly found with netCDF files): the sources coordinates are pixel indices and the targets are (longitude, latitude) coordinates, but we suspect that the sources to targets transform is some undetermined map projection, maybe Mercator. A linear approximation between those coordinates will give poor results; the results would be much better if all (longitude, latitude) coordinates were converted to the right projection first. However, that map projection may not be known, but we can try to guess it by trials-and-errors using a set of plausible projections. That set can be specified byaddLinearizers(Map, int...)
.
If the create(MathTransformFactory)
method finds that one of the specified projections seems a good fit,
it will automatically convert all target coordinates to that projection.
That selected projection is given by linearizer()
.- Since:
- 0.5
- Version:
- 1.2
- See Also:
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate class
Implementation of the map returned bygetControlPoints()
.private final class
Implementation of the map returned bygetControlPoints()
when no grid is used. -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate ProjectedTransformTry
If one of the linearizers have been applied, that linearizer.private double[]
An estimation of the Pearson correlation coefficient for each target dimension.(package private) final int
private final int[]
Number of grid columns and rows, ornull
if the coordinates are not distributed on a regular grid.private List<ProjectedTransformTry>
If the user suspects that the transform may be linear when the target is another space than the space oftargets
coordinates, projections toward spaces to try.private int
private double[][]
The arrays of source coordinate values.private double[][]
The arrays of target coordinate values.private LinearTransform
The transform created by the last call tocreate(MathTransformFactory)
. -
Constructor Summary
ConstructorsModifierConstructorDescriptionCreates a new linear transform builder for randomly distributed positions.LinearTransformBuilder
(int... gridSize) Creates a new linear transform builder for source positions distributed on a regular grid.private
LinearTransformBuilder
(LinearTransformBuilder original) Creates a temporary builder with all source fields from the given builder and no target arrays. -
Method Summary
Modifier and TypeMethodDescription(package private) final void
addLinearizers
(Map<String, org.opengis.referencing.operation.MathTransform> projections, boolean compensate, int[] projToGrid) Implementation ofaddLinearizers(Map, int...)
with a flag telling whether the inverse of selected projection shall be concatenated to the final transform.void
addLinearizers
(Map<String, org.opengis.referencing.operation.MathTransform> projections, int... projToGrid) Adds transforms to potentially apply on target control points before to compute the linear transform.private void
allocate
(int tgtDim) Allocates memory for a builder created for source positions distributed on a grid.(package private) final String
appendTo
(StringBuilder buffer, Class<?> caller, Locale locale, short resultKey) Appends a string representation of this builder into the given buffer.(package private) final ProjectedTransformTry
Returns linearizer which has been applied, ornull
if none.static LinearTransform
approximate
(org.opengis.referencing.operation.MathTransform gridToCRS, org.opengis.geometry.Envelope domain) Returns a linear approximation of the given transform for the specified domain.double[]
Returns the Pearson correlation coefficients of the transform created bycreate(…)
.create
(org.opengis.referencing.operation.MathTransformFactory factory) Creates a linear transform approximation from the source positions to the target positions.private void
ThrowsIllegalStateException
if this builder cannot be modified anymore.private static org.opengis.geometry.Envelope
envelope
(double[][] points, int numPoints) Implementation ofgetSourceEnvelope()
andgetTargetEnvelope()
.private MatrixSIS
fit()
Computes the matrix of the linear approximation.private int
flatIndex
(int[] source) Returns the offset where to store a target position for the given source position in the flattened array.private int
flatIndex
(org.opengis.geometry.DirectPosition source) Returns the index where to store a target position for the given source position in the flattened array.double[]
getControlPoint
(int[] source) Returns a single target coordinate for the given source coordinate, ornull
if none.Map<org.opengis.geometry.DirectPosition,
org.opengis.geometry.DirectPosition> Returns all control points as a map.(package private) final void
getControlRow
(int[] source, double[] target) More straightforward version ofgetControlPoint(int[])
for the case where thisLinearTransformBuilder
is known to have been built for grid source coordinates.(package private) final int
Returns the number of dimensions in the source grid, or -1 if this builder is not backed by a grid.int
Returns the number of dimensions in source positions.org.opengis.geometry.Envelope
Returns the envelope of source points (keys of the map returned bygetControlPoints()
).int
Returns the number of dimensions in target positions.org.opengis.geometry.Envelope
Returns the envelope of target points (values of the map returned bygetControlPoints()
).(package private) final Vector
getTransect
(int dimension, int[] start, int direction) Returns the coordinates of a single row or column in the given dimension.(package private) final int
gridSize
(int srcDim) Returns the grid size for the given dimension.(package private) final boolean
Returnstrue
ifcreate(MathTransformFactory)
has not yet been invoked.If target coordinates have been projected to another space, returns that projection.private org.opengis.geometry.MismatchedDimensionException
mismatchedDimension
(String name, int expected, int actual) Builds the exception message for an unexpected position dimension.private static String
noData()
Returns the error message to be given toIllegalStateException
when there is no data.private static org.opengis.geometry.DirectPosition
position
(org.opengis.geometry.coordinate.Position p) Returns the direct position of the given position, ornull
if none.private static void
resize
(double[][] data, int capacity) Resize all the given arrays to the given capacity.(package private) final NumberRange<Double>
resolveWraparoundAxis
(int dimension, int direction, double period) Tries to remove discontinuities in coordinates values caused by anti-meridian crossing.private static double
rms
(double[] correlations, double sqrtCorrLength) Returns a global estimation of correlation by computing the root mean square of values.private int
search
(int[] source) Returns the offset of the given source grid coordinate, or -1 if none.void
setControlPoint
(int[] source, double[] target) Sets a single matching control point pair.void
setControlPoints
(Map<? extends org.opengis.geometry.coordinate.Position, ? extends org.opengis.geometry.coordinate.Position> sourceToTarget) Sets all control point (source, target) pairs, overwriting any previous setting.(package private) final void
setControlPoints
(Vector[] coordinates) Sets all control points.void
setControlPoints
(org.opengis.referencing.operation.MathTransform gridToCRS) Sets all control point (source, target) pairs, overwriting any previous setting.(package private) final void
Sets the linearizers to a copy of those of the given builder.(package private) final Vector[]
sources()
Returns the vector of source coordinates.toString()
Returns a string representation of this builder for debugging purpose.(package private) final LinearTransform
Returns the transform computed bycreate(MathTransformFactory)
, ofnull
if that method has not yet been invoked.private Vector
vector
(double[] data) Wraps the given array in a vector of lengthnumPoints
.private void
verifySourceDimension
(int actual) Verifies that the given number of dimensions is equal to the expected value.Methods inherited from class org.apache.sis.referencing.operation.builder.TransformBuilder
nonNull
-
Field Details
-
gridSize
private final int[] gridSizeNumber of grid columns and rows, ornull
if the coordinates are not distributed on a regular grid. If the grid size is known, then thesources
coordinates do not need to be specified. -
sources
private double[][] sourcesThe arrays of source coordinate values. Accessed with indices in that order:sources[dimension][point]
. This layout allows to create only a few (typically two) large arrays instead of a multitude of small arrays. Example: {x[], y[]}.In the special case where
gridSize
is non-null, then this array does not need to be specified and can benull
. In such case, the source coordinates are implicitly:(0,0), (1,0), (2,0), (3,0) … (
gridSize
[0]-1, 0),
(0,1), (1,1), (2,1), (3,1) … (gridSize
[0]-1, 1),
(0,2), (1,2), (2,2), (3,2) … (gridSize
[0]-1, 2),
(0,gridSize
[1]-1) … (gridSize
[0]-1,gridSize
[1]-1). -
targets
private double[][] targetsThe arrays of target coordinate values. Accessed with indices in that order:targets[dimension][point]
. This layout allows to create only a few (typically two) large arrays instead of a multitude of small arrays. Example: {x[], y[], z[]}. This isnull
if not yet specified.Implementation note: we could use a flat array with (x₀, y₀), (x₁, y₁), (x₂, y₂), etc. coordinate tuples instead. Such flat array would be more convenient for some coordinate conversions withMathTransform
. But using array of arrays is more convenient for other calculations working on one dimension at time, make data more local for CPU, and also allows handling of more points. -
gridLength
final int gridLength -
numPoints
private int numPointsNumber of valid positions in thesources
ortargets
arrays. Note that the "valid" positions may containDouble.NaN
coordinate values. This field is only indicative if thisLinearTransformBuilder
instance has been created byLinearTransformBuilder(int...)
because we do not try to detect if user adds a new point or overwrites an existing one. -
linearizers
If the user suspects that the transform may be linear when the target is another space than the space oftargets
coordinates, projections toward spaces to try. Thecreate(MathTransformFactory)
method will try to apply those transforms ontargets
and check if they produce better fits.- See Also:
-
appliedLinearizer
If one of the linearizers have been applied, that linearizer. Otherwisenull
.- See Also:
-
transform
The transform created by the last call tocreate(MathTransformFactory)
. A non-null value means that this builder became unmodifiable. -
correlations
private transient double[] correlationsAn estimation of the Pearson correlation coefficient for each target dimension. This isnull
if not yet computed.
-
-
Constructor Details
-
LinearTransformBuilder
Creates a temporary builder with all source fields from the given builder and no target arrays. Calculated fields, namelycorrelations
andtransform
, are left uninitialized. Arrays are copied by references and their content shall not be modified. The new builder should not be made accessible to users since changes in this builder would be reflected in the source values of original builder. This constructor is reserved tocreate(MathTransformFactory)
internal usage.- Parameters:
original
- the builder from which to take array references of source values.
-
LinearTransformBuilder
public LinearTransformBuilder()Creates a new linear transform builder for randomly distributed positions.Tip: if the source coordinates are grid indices, then theLinearTransformBuilder(int...)
constructor will create a more efficient builder. -
LinearTransformBuilder
public LinearTransformBuilder(int... gridSize) Creates a new linear transform builder for source positions distributed on a regular grid. This constructor notifiesLinearTransformBuilder
that coordinate values of all source positions will be integers in the [0 …gridSize[0]
-1] range for the first dimension (typically column indices), in the [0 …gridSize[1]
-1] range for the second dimension (typically row indices), etc. The dimension of all source positions is the length of the givengridSize
array.An empty array is equivalent to invoking the no-argument constructor, i.e. no restriction is put on the source coordinates.
- Parameters:
gridSize
- the number of integer coordinate values in each grid dimension.- Throws:
IllegalArgumentException
- if a grid size is not strictly positive, or if the product of all values (∏gridSize
) is greater thanInteger.MAX_VALUE
.- Since:
- 0.8
-
-
Method Details
-
approximate
public static LinearTransform approximate(org.opengis.referencing.operation.MathTransform gridToCRS, org.opengis.geometry.Envelope domain) throws org.opengis.util.FactoryException Returns a linear approximation of the given transform for the specified domain. The source positions are integer coordinates included in the given envelope. The target positions are the results of transforming source coordinates with the givengridToCRS
transform.- Parameters:
gridToCRS
- the transform from source coordinates (grid indices) to target coordinates.domain
- domain of integer source coordinates for which to get a linear approximation.- Returns:
- a linear approximation of given transform for the specified domain.
- Throws:
org.opengis.util.FactoryException
- if the transform approximation cannot be computed.- Since:
- 1.1
- See Also:
-
gridSize
final int gridSize(int srcDim) Returns the grid size for the given dimension. It is caller's responsibility to ensure that this method is invoked only on instances created byLinearTransformBuilder(int...)
.- See Also:
-
allocate
private void allocate(int tgtDim) Allocates memory for a builder created for source positions distributed on a grid. All target values need to be initialized to NaN because we cannot rely onnumPoints
.If this builder has been created for randomly distributed source points, then the allocation should rather be performed as below:
-
resize
private static void resize(double[][] data, int capacity) Resize all the given arrays to the given capacity. This method should be invoked only forLinearTransformBuilder
instances created for randomly distributed source positions. -
search
private int search(int[] source) Returns the offset of the given source grid coordinate, or -1 if none. The algorithm implemented in this method is inefficient, but should rarely be used. This is only a fallback whenflatIndex(int[])
cannot be used. Callers is responsible to ensure that the number of dimensions match. -
flatIndex
private int flatIndex(int[] source) Returns the offset where to store a target position for the given source position in the flattened array. This method should be invoked only when thisLinearTransformBuilder
has been created for a grid of known size. Caller must have verified the array length before to invoke this method.- Throws:
IllegalArgumentException
- if a coordinate value is illegal.
-
flatIndex
private int flatIndex(org.opengis.geometry.DirectPosition source) Returns the index where to store a target position for the given source position in the flattened array. This method should be invoked only when thisLinearTransformBuilder
has been created for a grid of known size. Callers must have verified the position dimension before to invoke this method.- Throws:
IllegalArgumentException
- if a coordinate value is illegal.- See Also:
-
isModifiable
final boolean isModifiable()Returnstrue
ifcreate(MathTransformFactory)
has not yet been invoked. -
ensureModifiable
ThrowsIllegalStateException
if this builder cannot be modified anymore.- Throws:
IllegalStateException
-
verifySourceDimension
private void verifySourceDimension(int actual) throws org.opengis.geometry.MismatchedDimensionException Verifies that the given number of dimensions is equal to the expected value. No verification are done if the source point is the first point of randomly distributed points.- Throws:
org.opengis.geometry.MismatchedDimensionException
-
mismatchedDimension
private org.opengis.geometry.MismatchedDimensionException mismatchedDimension(String name, int expected, int actual) Builds the exception message for an unexpected position dimension. This method assumes that positions are stored in this builder as they are read from user-provided collection, withnumPoints
the index of the next point that we failed to add. -
noData
Returns the error message to be given toIllegalStateException
when there is no data. -
getGridDimensions
final int getGridDimensions()Returns the number of dimensions in the source grid, or -1 if this builder is not backed by a grid. Contrarily to the otherget*Dimensions()
methods, this method does not throw exception.- See Also:
-
getSourceDimensions
public int getSourceDimensions()Returns the number of dimensions in source positions. This is the length of thesource
array given in argument toget
/setControlPoint(int[], …)
methods. This is also the number of dimensions of theDirectPosition
keys in theMap
exchanged byget
/setControlPoints(Map)
methods.- Returns:
- the dimension of source points.
- Throws:
IllegalStateException
- if the number of source dimensions is not yet known.- Since:
- 0.8
- See Also:
-
MathTransform.getSourceDimensions()
-
getTargetDimensions
public int getTargetDimensions()Returns the number of dimensions in target positions. This is the length of thetarget
array exchanged byget
/setControlPoint(…, double[])
methods. This is also the number of dimensions of theDirectPosition
values in theMap
exchanged byget
/setControlPoints(Map)
methods.- Returns:
- the dimension of target points.
- Throws:
IllegalStateException
- if the number of target dimensions is not yet known.- Since:
- 0.8
- See Also:
-
MathTransform.getTargetDimensions()
-
getSourceEnvelope
public org.opengis.geometry.Envelope getSourceEnvelope()Returns the envelope of source points (keys of the map returned bygetControlPoints()
). The number of dimensions is equal togetSourceDimensions()
. This method returns the known minimum and maximum values (inclusive) for each dimension, not expanded to encompass full cell surfaces. In other words, the returned envelope encompasses only cell centers.If a grid size was
specified at construction time
, then those minimums and maximums are inferred from the grid size and are always integer values. Otherwise, the minimums and maximums are extracted from the control points and may be any floating point values. In any cases, the lower and upper values are inclusive.- Returns:
- the envelope of source points (cell centers), inclusive.
- Throws:
IllegalStateException
- if the source points are not yet known.- Since:
- 1.0
-
getTargetEnvelope
public org.opengis.geometry.Envelope getTargetEnvelope()Returns the envelope of target points (values of the map returned bygetControlPoints()
). The number of dimensions is equal togetTargetDimensions()
. The lower and upper values are inclusive. If a linearizer has been applied, then coordinates of the returned envelope are projected by that linearizer.- Returns:
- the envelope of target points.
- Throws:
IllegalStateException
- if the target points are not yet known.- Since:
- 1.0
-
envelope
private static org.opengis.geometry.Envelope envelope(double[][] points, int numPoints) Implementation ofgetSourceEnvelope()
andgetTargetEnvelope()
. -
position
private static org.opengis.geometry.DirectPosition position(org.opengis.geometry.coordinate.Position p) Returns the direct position of the given position, ornull
if none. -
setControlPoints
public void setControlPoints(org.opengis.referencing.operation.MathTransform gridToCRS) throws org.opengis.referencing.operation.TransformException Sets all control point (source, target) pairs, overwriting any previous setting. The source positions are all integer coordinates in a rectangle from (0, 0, …) inclusive togridSize
exclusive wheregridSize
is anint[]
array specified at construction time. The target positions are the results of transforming all source coordinates with the givengridToCRS
transform.- Parameters:
gridToCRS
- the transform from source coordinates (grid indices) to target coordinates.- Throws:
org.opengis.referencing.operation.TransformException
- if a coordinate value cannot be transformed.- Since:
- 1.1
- See Also:
-
setControlPoints
public void setControlPoints(Map<? extends org.opengis.geometry.coordinate.Position, ? extends org.opengis.geometry.coordinate.Position> sourceToTarget) throws org.opengis.geometry.MismatchedDimensionExceptionSets all control point (source, target) pairs, overwriting any previous setting. The source positions are the keys in given map, and the target positions are the associated values. The map should not contain two entries with the same source position. Coordinate reference systems are ignored. Null positions are silently ignored. Positions with NaN or infinite coordinates cause an exception to be thrown.All source positions shall have the same number of dimensions (the source dimension), and all target positions shall have the same number of dimensions (the target dimension). However, the source dimension does not need to be the same than the target dimension. Apache SIS currently supports only one- or two-dimensional source positions, together with arbitrary target dimension.
If this builder has been created with the
LinearTransformBuilder(int...)
constructor, then the coordinate values of all source positions shall be integers in the [0 …gridSize[0]
-1] range for the first dimension (typically column indices), in the [0 …gridSize[1]
-1] range for the second dimension (typically row indices), etc. This constraint does not apply for builders created with theLinearTransformBuilder()
constructor.- Parameters:
sourceToTarget
- a map of source positions to target positions. Source positions are assumed precise and target positions are assumed uncertain.- Throws:
IllegalStateException
- ifcreate(…)
has already been invoked.IllegalArgumentException
- if the given positions contain NaN or infinite coordinate values.IllegalArgumentException
- if this builder has been created for a grid but some source coordinates are not indices in that grid.org.opengis.geometry.MismatchedDimensionException
- if some positions do not have the expected number of dimensions.- Since:
- 0.8
-
getControlPoints
public Map<org.opengis.geometry.DirectPosition,org.opengis.geometry.DirectPosition> getControlPoints()Returns all control points as a map. Values are source coordinates and keys are target coordinates. The map is unmodifiable and is guaranteed to contain only non-null keys and values. The map is a view: changes in this builder are immediately reflected in the returned map.If
linearizer()
returns a non-empty value, then the values in the returned map are projected using that linearizer. This may happen only aftercreate(…)
has been invoked.- Returns:
- all control points in this builder.
- Since:
- 1.0
-
setControlPoint
public void setControlPoint(int[] source, double[] target) Sets a single matching control point pair. Source position is assumed precise and target position is assumed uncertain. If the given source position was already associated with another target position, then the old target position is discarded.Performance note: current implementation is efficient for builders created for a grid but inefficient for builders created for randomly distributed points. In the latter case, thesetControlPoints(Map)
method is a more efficient alternative.- Parameters:
source
- the source coordinates. If this builder has been created with theLinearTransformBuilder(int...)
constructor, then for every index i thesource[i]
value shall be in the [0 …gridSize[i]
-1] range inclusive. If this builder has been created with theLinearTransformBuilder()
constructor, then no constraint apply.target
- the target coordinates, assumed uncertain.- Throws:
IllegalStateException
- ifcreate(…)
has already been invoked.IllegalArgumentException
- if this builder has been created for a grid but some source coordinates are out of index range, or iftarget
contains NaN of infinite numbers.org.opengis.geometry.MismatchedDimensionException
- if the source or target position does not have the expected number of dimensions.- Since:
- 0.8
-
getControlPoint
public double[] getControlPoint(int[] source) Returns a single target coordinate for the given source coordinate, ornull
if none. This method can be used for retrieving points set by previous calls tosetControlPoint(int[], double[])
orsetControlPoints(Map)
.If
linearizer()
returns a non-empty value, then the returned values are projected using that linearizer. This may happen only if this method is invoked aftercreate(…)
.Performance note: current implementation is efficient for builders created for a grid but inefficient for builders created for randomly distributed points.- Parameters:
source
- the source coordinates. If this builder has been created with theLinearTransformBuilder(int...)
constructor, then for every index i thesource[i]
value shall be in the [0 …gridSize[i]
-1] range inclusive. If this builder has been created with theLinearTransformBuilder()
constructor, then no constraint apply.- Returns:
- the target coordinates associated to the given source, or
null
if none. - Throws:
IllegalArgumentException
- if this builder has been created for a grid but some source coordinates are out of index range.org.opengis.geometry.MismatchedDimensionException
- if the source position does not have the expected number of dimensions.- Since:
- 0.8
-
setControlPoints
Sets all control points. This method can be invoked only for points on a grid. The length of given vectors must be equal to the total number of cells in the grid. The first vector provides the x coordinates; the second vector provides the y coordinates, etc.. Coordinates are stored in row-major order (column index varies faster, followed by row index).- Parameters:
coordinates
- coordinates in each target dimensions, stored in row-major order.- Throws:
IllegalStateException
- ifcreate(…)
has already been invoked.
-
getControlRow
final void getControlRow(int[] source, double[] target) More straightforward version ofgetControlPoint(int[])
for the case where thisLinearTransformBuilder
is known to have been built for grid source coordinates. This method is forLocalizationGridBuilder.create(MathTransformFactory)
internal usage.- Parameters:
source
- the source coordinates.target
- where to store target coordinates for a full row.
-
getTransect
Returns the coordinates of a single row or column in the given dimension. This method can be invoked only when thisLinearTransformBuilder
is known to have been built for grid source coordinates.Note: while this method is primarily for row and columns, it can be generalized to more dimensions.The returned vector is a view; changes in the returned vector will be reflected in this builder.- Parameters:
dimension
- the dimension of source point for which to get coordinate values.start
- index of the first coordinate value to get.direction
- 0 for getting a row, 1 for getting a column.- Returns:
- coordinate values for specified row or column in the given dimension.
-
resolveWraparoundAxis
Tries to remove discontinuities in coordinates values caused by anti-meridian crossing. This is the implementation ofLocalizationGridBuilder.resolveWraparoundAxis(int, int, double)
public method. See that method for javadoc.- Parameters:
dimension
- the dimension to process, from 0 inclusive togetTargetDimensions()
exclusive. This is 0 for longitude dimension in a (longitudes, latitudes) grid.direction
- the direction to walk through: 0 for columns or 1 for rows (higher dimensions are also possible). Value can be from 0 inclusive togetSourceDimensions()
exclusive. The recommended direction is the direction of most stable values, typically 1 (rows) for longitudes.period
- that wraparound range (typically 360° for longitudes). Must be strictly positive.- Returns:
- the range of coordinate values in the specified dimension after correction for wraparound values.
- Throws:
IllegalStateException
- ifcreate(…)
has already been invoked.
-
sources
Returns the vector of source coordinates. It is caller responsibility to ensure that this builder is not backed by a grid. -
addLinearizers
public void addLinearizers(Map<String, org.opengis.referencing.operation.MathTransform> projections, int... projToGrid) Adds transforms to potentially apply on target control points before to compute the linear transform. This method can be invoked when the source to target transform would possibly be more linear if target was another space than the current one. If linearizers have been specified, then thecreate(MathTransformFactory)
method will try to apply each transform on target coordinates and check which one get the best correlation coefficients.Exactly one of the specified transforms will be selected. If applying no transform is an acceptable solution, then an identity transform should be included in the given
projections
map. The transform selected byLinearTransformBuilder
will be given bylinearizer()
.Linearizers are specified as a collection of
MathTransform
s from current target coordinates to some other spaces where sources to new targets transforms may be more linear. Keys in the map are arbitrary identifiers. Values in the map should be non-linear transforms;LinearTransform
s (other than identity) should be avoided because they will consume processing power for no correlation improvement.Error handling
If aTransformException
occurred or if some transform results were NaN or infinite, then theMathTransform
that failed will be ignored. If all transforms fail, then aFactoryException
will be thrown by thecreate(…)
method.Dimensions mapping
TheprojToGrid
argument mapsprojections
dimensions to target dimensions of this builder. For example ifprojToGrid
array is{2,1}
, then coordinate values in target dimensions 2 and 1 of this grid will be used as source coordinates in dimensions 0 and 1 respectively for all given projections. Likewise, the projection results in dimensions 0 and 1 of all projections will be stored in target dimensions 2 and 1 respectively of this grid.The
projToGrid
argument can be omitted or null, in which case {0, 1, 2 …getTargetDimensions()
- 1} is assumed. All givenprojections
shall have a number of source and target dimensions equals to the length of theprojToGrid
array. It is possible to invoke this method many times with differentprojToGrid
argument values.- Parameters:
projections
- projections from current target coordinates to other spaces which may result in more linear transforms.projToGrid
- the target dimensions to project, or null or omitted for projecting all target dimensions in same order.- Throws:
IllegalStateException
- ifcreate(…)
has already been invoked.org.opengis.geometry.MismatchedDimensionException
- if a projection does not have the expected number of dimensions.- Since:
- 1.0
- See Also:
-
addLinearizers
final void addLinearizers(Map<String, org.opengis.referencing.operation.MathTransform> projections, boolean compensate, int[] projToGrid) Implementation ofaddLinearizers(Map, int...)
with a flag telling whether the inverse of selected projection shall be concatenated to the final transform. This method is non-public because thereverseAfterLinearization
flag has no purpose for thisLinearTransformBuilder
class; it is useful only forLocalizationGridBuilder
. -
setLinearizers
Sets the linearizers to a copy of those of the given builder. This is used by copy constructors. -
create
public LinearTransform create(org.opengis.referencing.operation.MathTransformFactory factory) throws org.opengis.util.FactoryException Creates a linear transform approximation from the source positions to the target positions. This method assumes that source positions are precise and that all uncertainties are in target positions. If linearizers have been specified, then this method will project all target coordinates using one of those linearizers in order to get a more linear transform. If such projection is applied, thenlinearizer()
will return a non-empty value after this method call.If this method is invoked more than once, the previously created transform instance is returned.
- Specified by:
create
in classTransformBuilder
- Parameters:
factory
- the factory to use for creating the transform, ornull
for the default factory. TheMathTransformFactory.createAffineTransform(Matrix)
method of that factory shall returnLinearTransform
instances.- Returns:
- the fitted linear transform.
- Throws:
org.opengis.util.FactoryException
- if the transform cannot be created, for example because the source or target points have not be specified.- Since:
- 0.8
-
fit
Computes the matrix of the linear approximation. This is the implementation ofcreate(MathTransformFactory)
without the step creating theLinearTransform
from a matrix. Thecorrelations
field is set as a side effect of this method call.In current implementation, the transform represented by the returned matrix is always affine (i.e. the last row is fixed to [0 0 … 0 1]). If this is no longer the case in a future version, some codes may not work anymore. Search for
isAffine()
statements for locating codes that depend on affine transform assumption.- Throws:
org.opengis.util.FactoryException
-
vector
Wraps the given array in a vector of lengthnumPoints
. This method should be invoked only when this builder has been created byLinearTransformBuilder()
. This can be identified bysources != null
orgridSize == null
. -
rms
private static double rms(double[] correlations, double sqrtCorrLength) Returns a global estimation of correlation by computing the root mean square of values. -
linearizer
If target coordinates have been projected to another space, returns that projection. This method returns a non-empty value ifaddLinearizers(Map, int...)
has been invoked with a non-empty map, followed by acreate(MathTransformFactory)
call. In such case,LinearTransformBuilder
selects a linearizer identified by the returned key - value entry. The entry key is one of the keys of the maps given toaddLinearizers(…)
. The entry value is the associatedMathTransform
, possibly modified as described in the axis order section below.The envelope returned by
getTargetEnvelope()
and all control points returned bygetControlPoint(int[])
are projected by the selected transform. Consequently, if the target coordinates of original control points are desired, then the transform returned bycreate(…)
needs to be concatenated with the inverse of the transform returned by thislinearizer()
method.Axis order
The source coordinates expected by the returned transform are the control points target coordinates. The returned transform will contain an operation step performing axis filtering and swapping implied by theprojToGrid
argument that was given to theaddLinearizers(…, projToGrid)}
method. Consequently, if theprojToGrid
argument was not an arithmetic progression, then the transform returned by this method will not be one of the instances given toaddLinearizers(…)
.- Returns:
- the projection applied on target coordinates before to compute a linear transform.
- Since:
- 1.1
-
appliedLinearizer
Returns linearizer which has been applied, ornull
if none. -
correlation
public double[] correlation()Returns the Pearson correlation coefficients of the transform created bycreate(…)
. The closer those coefficients are to +1 or -1, the better the fit. This method returnsnull
ifcreate(…)
has not yet been invoked. If non-null, the array length is equal to the number of target dimensions.- Returns:
- estimation of Pearson correlation coefficients for each target dimension,
or
null
ifcreate(…)
has not been invoked yet.
-
transform
Returns the transform computed bycreate(MathTransformFactory)
, ofnull
if that method has not yet been invoked. -
toString
Returns a string representation of this builder for debugging purpose. Current implementation shows the following information:- Number of points.
- Linearizers and their correlation coefficients (if available).
- The linear transform (if already computed).
-
appendTo
final String appendTo(StringBuilder buffer, Class<?> caller, Locale locale, short resultKey) throws IOException Appends a string representation of this builder into the given buffer.- Parameters:
buffer
- where to append the string representation.caller
- the class name to report.locale
- the locale for formatting messages and some numbers, ornull
for the default.resultKey
- eitherVocabulary.Keys.Result
orVocabulary.Keys.LinearTransformation
.- Returns:
- the line separator, for convenience of callers who wants to append more content.
- Throws:
IOException
- should never happen because we write in aStringBuilder
.
-