org.openimaj.math.geometry.shape

## Class EllipseUtilities

• public class EllipseUtilities
extends Object
An elliptical shape
Author:
Jonathon Hare (jsh2@ecs.soton.ac.uk)

• ### Method Detail

• #### ellipseFromEquation

public static Ellipse ellipseFromEquation(double centerX,
double centerY,
double major,
double minor,
double rotation)
Construct an ellipse using a parametric ellipse equation, namely: X(t) = centerX + major * cos(t) * cos(rotation) - minor * sin(t) * sin(rotation) Y(t) = centerY + major * cos(t) * cos(rotation) + minor * sin(t) * sin(rotation)
Parameters:
centerX -
centerY -
major -
minor -
rotation -
Returns:
an ellipse
• #### ellipseFromSecondMoments

public static Ellipse ellipseFromSecondMoments(float x,
float y,
Jama.Matrix secondMoments)
Construct ellipse from second moment matrix and centroid.
Parameters:
x - x-ordinate of centroid
y - y-ordinate of centroid
secondMoments - second moments matrix
Returns:
an ellipse
• #### ellipseFromSecondMoments

public static Ellipse ellipseFromSecondMoments(float x,
float y,
Jama.Matrix secondMoments,
double scaleFactor)
Construct ellipse from second moment matrix, scale-factor and centroid.
Parameters:
x - x-ordinate of centroid
y - y-ordinate of centroid
secondMoments - second moments matrix
scaleFactor - the scale factor
Returns:
an ellipse
• #### ellipseFromCovariance

public static Ellipse ellipseFromCovariance(float x,
float y,
Jama.Matrix sm,
float sf)
Construct ellipse from covariance matrix, scale-factor and centroid.
Parameters:
x - x-ordinate of centroid
y - y-ordinate of centroid
sm - covariance matrix
sf - scale-factor
Returns:
an ellipse
• #### ellipseToCovariance

public static Jama.Matrix ellipseToCovariance(Ellipse e)
Create the covariance matrix of an ellipse.
Parameters:
e - the ellipse
Returns:
the corresponding covariance matrix
• #### fromTransformMatrix2x2

public static Ellipse fromTransformMatrix2x2(Jama.Matrix U,
float x,
float y,
float scale)
Create an ellipse.
Parameters:
U -
x -
y -
scale -
Returns:
an ellipse