Module imagingbook.common

Package imagingbook.common.geometry.fitting.circle.algebraic

Class CircleFitPratt

java.lang.Object

imagingbook.common.geometry.fitting.circle.algebraic.CircleFitPratt

All Implemented Interfaces:

CircleFitAlgebraic

public class CircleFitPratt
extends Object
implements CircleFitAlgebraic

This is an implementation of the algebraic circle fitting algorithm by Pratt [1], as described in [2] (Sec. 5.5-5.6). The algorithm uses singular-value decomposition (SVD) and eigen-decomposition. See [3, Alg. 11.2] for additional details.

Fits to exactly 3 (non-collinear) points are handled properly. Data centering is used to improve numerical stability (alternatively, a reference point can be specified).

[1] V. Pratt. "Direct least-squares fitting of algebraic surfaces". ACM SIGGRAPH Computer Graphics 21(4), 145–152 (July 1987).
[2] N. Chernov. "Circular and Linear Regression: Fitting Circles and Lines by Least Squares". Monographs on Statistics and Applied Probability. Taylor & Francis (2011).
[3] W. Burger, M.J. Burge, Digital Image Processing – An Algorithmic Introduction, 3rd ed, Springer (2022).

Nested Class Summary

Nested classes/interfaces inherited from interface imagingbook.common.geometry.fitting.circle.algebraic.CircleFitAlgebraic

CircleFitAlgebraic.FitType

Constructor Summary

Constructors

Constructor	Description
CircleFitPratt(Pnt2d[] points)	Constructor.
CircleFitPratt(Pnt2d[] points, Pnt2d xref)	Constructor.

Method Summary

Modifier and Type	Method	Description
double[]	getParameters()	Returns parameters (A, B, C, D) of the AlgebraicCircle or null if the fit was unsuccessful.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface imagingbook.common.geometry.fitting.circle.algebraic.CircleFitAlgebraic

getAlgebraicCircle, getGeometricCircle, normalizeP

Constructor Details

CircleFitPratt

public CircleFitPratt(Pnt2d[] points)

Constructor. The centroid of the sample points is used as the reference point.

Parameters:

points - sample points

CircleFitPratt

public CircleFitPratt(Pnt2d[] points,
 Pnt2d xref)

Constructor. The centroid of the sample points is used as the reference point for data centering if null is passed for xref.

Parameters:

points - sample points

xref - reference point or null

Method Details

getParameters

public double[] getParameters()

Description copied from interface: CircleFitAlgebraic

Returns parameters (A, B, C, D) of the AlgebraicCircle or null if the fit was unsuccessful. Parameters are not normalized.

Specified by:

getParameters in interface CircleFitAlgebraic

Returns:

the algebraic circle parameters or null