opencv: imgproc.Moments missing in OpenCV 3.0 for Android

For who need it now. Add this into Imgproc.java
public static Moments contourMoments( MatOfPoint contour ) { Moments m = new Moments(); int lpt = contour.checkVector(2); boolean is_float = true;//(contour.depth() == CvType.CV_32F); Point[] ptsi = contour.toArray(); //PointF[] ptsf = contour.toArray();

                    //CV_Assert( contour.depth() == CV_32S || contour.depth() == CV_32F );

                    if( lpt == 0 )
                            return m;

                    double a00 = 0, a10 = 0, a01 = 0, a20 = 0, a11 = 0, a02 = 0, a30 = 0, a21 = 0, a12 = 0, a03 = 0;
                    double xi, yi, xi2, yi2, xi_1, yi_1, xi_12, yi_12, dxy, xii_1, yii_1;


                    {
                            xi_1 = ptsi[lpt-1].x;
                            yi_1 = ptsi[lpt-1].y;
                    }

                    xi_12 = xi_1 * xi_1;
                    yi_12 = yi_1 * yi_1;

                    for( int i = 0; i < lpt; i++ )
                    {

                            {
                                    xi = ptsi[i].x;
                                    yi = ptsi[i].y;
                            }

                            xi2 = xi * xi;
                            yi2 = yi * yi;
                            dxy = xi_1 * yi - xi * yi_1;
                            xii_1 = xi_1 + xi;
                            yii_1 = yi_1 + yi;

                            a00 += dxy;
                            a10 += dxy * xii_1;
                            a01 += dxy * yii_1;
                            a20 += dxy * (xi_1 * xii_1 + xi2);
                            a11 += dxy * (xi_1 * (yii_1 + yi_1) + xi * (yii_1 + yi));
                            a02 += dxy * (yi_1 * yii_1 + yi2);
                            a30 += dxy * xii_1 * (xi_12 + xi2);
                            a03 += dxy * yii_1 * (yi_12 + yi2);
                            a21 += dxy * (xi_12 * (3 * yi_1 + yi) + 2 * xi * xi_1 * yii_1 +
                                    xi2 * (yi_1 + 3 * yi));
                            a12 += dxy * (yi_12 * (3 * xi_1 + xi) + 2 * yi * yi_1 * xii_1 +
                                    yi2 * (xi_1 + 3 * xi));
                            xi_1 = xi;
                            yi_1 = yi;
                            xi_12 = xi2;
                            yi_12 = yi2;
                    }
                    float FLT_EPSILON = 1.19209e-07f;
                    if( Math.abs(a00) > FLT_EPSILON )
                    {
                            double db1_2, db1_6, db1_12, db1_24, db1_20, db1_60;

                            if( a00 > 0 )
                            {
                                    db1_2 = 0.5;
                                    db1_6 = 0.16666666666666666666666666666667;
                                    db1_12 = 0.083333333333333333333333333333333;
                                    db1_24 = 0.041666666666666666666666666666667;
                                    db1_20 = 0.05;
                                    db1_60 = 0.016666666666666666666666666666667;
                            }
                            else
                            {
                                    db1_2 = -0.5;
                                    db1_6 = -0.16666666666666666666666666666667;
                                    db1_12 = -0.083333333333333333333333333333333;
                                    db1_24 = -0.041666666666666666666666666666667;
                                    db1_20 = -0.05;
                                    db1_60 = -0.016666666666666666666666666666667;
                            }

                            // spatial moments
                            m.m00 = a00 * db1_2;
                            m.m10 = a10 * db1_6;
                            m.m01 = a01 * db1_6;
                            m.m20 = a20 * db1_12;
                            m.m11 = a11 * db1_24;
                            m.m02 = a02 * db1_12;
                            m.m30 = a30 * db1_20;
                            m.m21 = a21 * db1_60;
                            m.m12 = a12 * db1_60;
                            m.m03 = a03 * db1_20;

                           m.completeState();
                    }
                    return m;
            }

PepperX,

Prior to the workaround, to get the moments, you’d call the regular moments method in Imgproc, namely

Imgproc.moment(Mat array);

That method doesn’t work. Whatisor’s workaround is the new methods he presents for Imgproc.

Imgproc.contourMoments(MapOfPoint contour);

I copied that into the version of Imgproc under the OpenCVLibrary310 module in my project, and used that with a MatOfPoint contour to get the moments.

Hope that helps,

tonyc

On Tue, Oct 25, 2016 at 1:42 AM, PepperX notifications@github.com wrote:

@tonyc10 https://github.com/tonyc10

What is the right name/signature of the existing method ?

my declarations of MatOfPoint looks like:

List<MatOfPoint> contours = new ArrayList<>(); then with findcontours() and drawcontours() works well.

But with List<Moments> mu = new ArrayList<>(contours.size());

The problem begins.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/opencv/opencv/issues/5017#issuecomment-255950393, or mute the thread https://github.com/notifications/unsubscribe-auth/ADjrbYrXbt0V1q2x1elyZlceN9JjjgSYks5q3aTrgaJpZM4FgVhM .

PepperX – I think you took the right steps. The Moments should all be calculated correctly using whatisor’s code.
Note that whatinor’s method has a slightly different name/signature than the existing one. Also, are you passing a valid contour (MatOfPoint) to the method? What do the moments look like in the resulting Moment object?

Thanks @whatisor ,but i still have a problem after add the public static on imgproc.java ,i don’t know what should i do after that , my syntax Moments still red ,someone can help me please ? hopefully someone can help me 😃 Thanks