BSplineFit Class Reference

#include <CTiglBSplineFit.h>

Public Types
enum	error { NoError = 0, MatrixSingular, InvalidInput }

Public Member Functions
TIGL_EXPORT	BSplineFit (int deg, int ncp)
	BSplineFit Class to fit a B-spline to data points. More...
TIGL_EXPORT Handle_Geom_BSplineCurve	Curve () const
	Returns the resulting curve. Returns Null in case of an error. More...
TIGL_EXPORT error	Fit (const TColgp_Array1OfPnt &points, const std::vector< double > &parameters)
	Fits the given points by a B-spline. More...
TIGL_EXPORT error	Fit (const TColgp_Array1OfPnt &points, double alpha=1.0)
	Fits the given points by a B-spline using the centripetal parameterization scheme (alpha=0.5) More...
TIGL_EXPORT error	FitOptimal (const TColgp_Array1OfPnt &points, double alpha=1.0, double eps=1.0E-3, int maxIter=100)
	Fits, by optimizing the fit parameters This is an iterative algorithm and requires more time than the other fit algorithms. More...
TIGL_EXPORT double	GetMaxError ()
	Computes the maximum error of the fit. More...

Private Member Functions
void	computeKnots ()
	Computes an uniform knot vector. More...
void	computeParameters (double alpha)
	Calculates curve parameter t_k [0, 1], which corresponds to the arc lengths. More...
void	copyPoints (const TColgp_Array1OfPnt &)
	Copies the points to be fitted. More...
error	fitCurve ()
	Fits the given points by a Bezier spline. More...
void	initSystem (class math_Matrix &A, class math_Vector &rhsx, class math_Vector &rhsy, class math_Vector &rhsz)
	Computes the matrix and the right hand side of the system to be solved. More...
void	optimizeParameters ()
	Recalculates the curve parameters t_k after the control points are fitted to achieve an even better fit. More...

Private Attributes
Handle_Geom_BSplineCurve	_curve
	The resulting B-spline curve. More...
int	_degree
	degree of the B-spline More...
TColStd_Array1OfReal	_knots
	uniform knot vector of the B-spline More...
int	_ncp
	Number of control points of the B-spline. More...
std::vector< double >	_px
	curve coordinates to be fitted by the B-spline More...
std::vector< double >	_py
std::vector< double >	_pz
std::vector< double >	t
	parameters at which the curve is sampled More...

Detailed Description

Copyright (C) 2015 DLR-SC

Author: Martin Siggel

A algorithm that fits a bspline to the given data points.

This iterative algorithm works as follows:

0) Initialize parameters t_k with uniform distance 1) Find control points, by minimizing the distance C(t_k) - p_k for all k using a least square fit. 2) Optimize all t_k, such that the distance C(t_k) - p_k becomes smaller. Go back to (1)

Member Enumeration Documentation

error

enum BSplineFit::error

Enumerator
NoError
MatrixSingular
InvalidInput

Constructor & Destructor Documentation

BSplineFit()

TIGL_EXPORT BSplineFit::BSplineFit	(	int	deg,
		int	ncp
	)

BSplineFit Class to fit a B-spline to data points.

Parameters

deg	Degree of the resulting B-spline
ncp	Number of control points of the B-spline (ncp > deg)
eps	Tolerance of the iterative method
maxIter	Maximum number of iterations

Member Function Documentation

computeKnots()

void BSplineFit::computeKnots ( )

private

Computes an uniform knot vector.

computeParameters()

void BSplineFit::computeParameters ( double  alpha )

private

Calculates curve parameter t_k [0, 1], which corresponds to the arc lengths.

copyPoints()

void BSplineFit::copyPoints ( const TColgp_Array1OfPnt &  )

private

Copies the points to be fitted.

Curve()

TIGL_EXPORT Handle_Geom_BSplineCurve BSplineFit::Curve

(

)

const

Returns the resulting curve. Returns Null in case of an error.

Fit() [1/2]

TIGL_EXPORT error BSplineFit::Fit	(	const TColgp_Array1OfPnt &	points,
		const std::vector< double > &	parameters
	)

Fits the given points by a B-spline.

Fit() [2/2]

TIGL_EXPORT error BSplineFit::Fit	(	const TColgp_Array1OfPnt &	points,
		double	alpha = 1.0
	)

Fits the given points by a B-spline using the centripetal parameterization scheme (alpha=0.5)

fitCurve()

error BSplineFit::fitCurve ( )

private

Fits the given points by a Bezier spline.

FitOptimal()

TIGL_EXPORT error BSplineFit::FitOptimal	(	const TColgp_Array1OfPnt &	points,
		double	alpha = 1.0,
		double	eps = 1.0E-3,
		int	maxIter = 100
	)

Fits, by optimizing the fit parameters This is an iterative algorithm and requires more time than the other fit algorithms.

GetMaxError()

TIGL_EXPORT double BSplineFit::GetMaxError

(

)

Computes the maximum error of the fit.

initSystem()

void BSplineFit::initSystem ( class math_Matrix &  A, class math_Vector &  rhsx, class math_Vector &  rhsy, class math_Vector &  rhsz  )

private

Computes the matrix and the right hand side of the system to be solved.

optimizeParameters()

void BSplineFit::optimizeParameters ( )

private

Recalculates the curve parameters t_k after the control points are fitted to achieve an even better fit.

Field Documentation

_curve

Handle_Geom_BSplineCurve BSplineFit::_curve

private

The resulting B-spline curve.

_degree

int BSplineFit::_degree

private

degree of the B-spline

_knots

TColStd_Array1OfReal BSplineFit::_knots

private

uniform knot vector of the B-spline

_ncp

int BSplineFit::_ncp

private

Number of control points of the B-spline.

_px

std::vector<double> BSplineFit::_px

private

curve coordinates to be fitted by the B-spline

_py

std::vector<double> BSplineFit::_py

private

_pz

std::vector<double> BSplineFit::_pz

private

t

std::vector<double> BSplineFit::t

private

parameters at which the curve is sampled

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The documentation for this class was generated from the following file:

• CTiglBSplineFit.h