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Hi,
I'm working on my 3d reconstruction project and I'm having problems with obtaining proper epipolar lines.


My main concern is that they not intersect keypoints.
I'm using SURF feature detector (java_3d_reconstruction\src\KeyPairsDetector.java)

private void detectKeyPoints(MatOfKeyPoint keyPoints1, MatOfKeyPoint keyPoints2) {
    FeatureDetector surfDetector = FeatureDetector.create(FeatureDetector.SURF);
    surfDetector.detect(getImg1(), keyPoints1);
    surfDetector.detect(getImg2(), keyPoints2);
}

than FLANNBASED matcher (java_3d_reconstruction\src\KeyPairsDetector.java)

DescriptorMatcher descriptorMatcher = DescriptorMatcher.create(DescriptorMatcher.FLANNBASED);
        ArrayList<MatOfDMatch> matches = new ArrayList<MatOfDMatch>();
        descriptorMatcher.knnMatch(descriptors1, descriptors2, matches, 1);

and I'm filtering good matches using mask obtained by findHomography with RANSAC (java_3d_reconstruction\src\KeyPairsDetector.java)

Mat mask = new Mat();
        Calib3d.findHomography(srcPoints, dstPoints, Calib3d.RANSAC, 5, mask);

        List<MatOfDMatch> goodMatches = getInliers(mask, matches);

Then I'm calculating fundamental matrix using 8 point algorithm (java_3d_reconstruction\src\EpipolarGeometry.java):

private void computeFundamentalMatrix() {
        fundamentalMatrix  = Calib3d.findFundamentalMat(srcPoints, dstPoints, Calib3d.FM_8POINT, 0.0, 0.0);
    }

computing epipolar lines (java_3d_reconstruction\src\EpipolarGeometry.java):

private void computeEpiLines() {
        epilinesSrc = new Mat();
        epilinesDst = new Mat();

        Calib3d.computeCorrespondEpilines(srcPoints, 1, fundamentalMatrix, epilinesDst);
        Calib3d.computeCorrespondEpilines(dstPoints, 2, fundamentalMatrix, epilinesSrc);
    }

and drawing them (java_3d_reconstruction\src\EpipolarGeometry.java):

public Mat drawEpiLines(Mat outImg) {

        int epiLinesCount = epilinesSrc.rows();

        double a, b, c;

        for (int line = 0; line < epiLinesCount; line++) {
            a = epilinesSrc.get(line, 0)[0];
            b = epilinesSrc.get(line, 0)[1];
            c = epilinesSrc.get(line, 0)[2];

            int x0 = 0;
            int y0 = (int) (-(c + a * x0) / b);
            int x1 = outImg.cols() / 2;
            int y1 = (int) (-(c + a * x1) / b);

            Point p1 = new Point(x0, y0);
            Point p2 = new Point(x1, y1);
            Scalar color = new Scalar(255, 255, 255);
            Core.line(outImg, p1, p2, color);

        }

        for (int line = 0; line < epiLinesCount; line++) {
            a = epilinesDst.get(line, 0)[0];
            b = epilinesDst.get(line, 0)[1];
            c = epilinesDst.get(line, 0)[2];

            int x0 = outImg.cols() / 2;
            int y0 = (int) (-(c + a * x0) / b);
            int x1 = outImg.cols();
            int y1 = (int) (-(c + a * x1) / b);

            Point p1 = new Point(x0, y0);
            Point p2 = new Point(x1, y1);
            Scalar color = new Scalar(255, 255, 255);
            Core.line(outImg, p1, p2, color);

        }
        return outImg;
    }

The main code:

public class Main {
    static {
        System.loadLibrary("opencv_java2410");
    }
    public static void main(String[] args) {
        System.loadLibrary("opencv_java2410");


        Mat img1 = Highgui.imread("images\\SylvainJpg\\S01.jpg", Highgui.CV_LOAD_IMAGE_GRAYSCALE);
        Mat img2 = Highgui.imread("images\\SylvainJpg\\S02.jpg", Highgui.CV_LOAD_IMAGE_GRAYSCALE);

        KeyPairsDetector keyPairsDetector = new KeyPairsDetector(img1,img2);
        EpipolarGeometry epipolarGeometry = new EpipolarGeometry(keyPairsDetector.srcSortedGoodPoints,
                keyPairsDetector.dstSortedGoodPoints);

        Mat matchedImg = keyPairsDetector.drawMatchesAndKeyPoints();
        epipolarGeometry.drawEpiLines(matchedImg);

        Highgui.imwrite("images\\SylvainJpg\\S00c.jpg", matchedImg);

    }
}

Whole code is available here GitHub repo

Could you please help me work out what is wrong here?