how to draw irregular circles java [closed]

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In this App I am drawing the circle of a car wheel, but what I need is to draw the contour, for example when the wheel is deflated I want to draw is the contour (ellipse) and not a circle.

for example: image: link text

now i'm doing the red line, but I want the green one

EL CODIGO ES:

import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.MatOfRect; import org.opencv.core.Point; import org.opencv.core.Rect; import org.opencv.core.Scalar; import org.opencv.core.Size; import org.opencv.highgui.Highgui; import org.opencv.imgproc.Imgproc; import org.opencv.objdetect.CascadeClassifier;

class DetectarCirculos {

public void run() {

    int radio = 0; // radius
    Point pnt = null;
    Mat fuente = Highgui.imread("imagenes/rueda.jpg", Highgui.CV_LOAD_IMAGE_COLOR); // font
    Mat destino = new Mat(fuente.rows(), fuente.cols(), fuente.type()); // target

    Imgproc.cvtColor(fuente, destino, Imgproc.COLOR_RGB2GRAY);

    Imgproc.GaussianBlur(destino, destino, new Size(3, 3), 0, 0);
    Mat circulos = new Mat(); // circles
    //(Mat image, Mat circles,        int method  ,  dp, minDist, param1,  param2, minRadius, maxRadius)
    Imgproc.HoughCircles(destino, circulos, Imgproc.CV_HOUGH_GRADIENT, 1, 1, 200, 100, 30, 300);
    int radios;
    Point pt;
    System.out.println("" + circulos.cols());

    for (int x = 0; x < circulos.cols(); x++) {
        double vCirculo[] = circulos.get(0, x);

        if (vCirculo == null) {
            break;
        }

        pt = new Point(Math.round(vCirculo[0]), Math.round(vCirculo[1]));
        radios = (int) Math.round(vCirculo[2]);

        // encontrar radio mayor - finding greater radius
        if (radio < radios) {
            radio = radios;
            pnt = pt;
        }
    }
    // dibujar circulos encontrados - draw found circles
    if (circulos.cols()!=0) {
        Core.circle(destino, pnt, radio, new Scalar(255, 255, 255), 3);
        Core.circle(destino, pnt, 1, new Scalar(255, 0, 0), 3);
    }else{
        System.out.println("no se encontraron circulos"); // there's no circles
    }

    Highgui.imwrite("foundCircles.png", destino);
    System.out.println("radio mayor "+radio);
}

}

public class Main {

public static void main(String[] args) {
    System.out.println("bienvenido a circulandia");

    // Load the native library.
    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    new DetectarCirculos().run();
}

}

THANKS!