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.
TIGL_EXPORT Handle_Geom_BSplineCurve	Curve () const
	Returns the resulting curve. Returns Null in case of an error.
TIGL_EXPORT error	Fit (const TColgp_Array1OfPnt &points, const std::vector< double > &parameters)
	Fits the given points by a B-spline.
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).
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.
TIGL_EXPORT double	GetMaxError ()
	Computes the maximum error of the fit.

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

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

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, math_Vector & rhsx, math_Vector & rhsy, 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