java - OpenCV Java : Compare Bounding Rect's y value, 清除不需要的

Question

在下图中，应用程序检测到多个“黑色”并在它们周围绘制了一个边框。现在我想比较每个矩形的rect3.tl().y值，只保留最低的一个，删除其他边界矩形。但我不确定如何着手做到这一点。

代码:

Rect rectBlack = new Rect();
    Bitmap roiBitmap = null;
    Scalar green = new Scalar(0, 255, 0, 255);
    Mat sourceMat = new Mat(sourceBitmap.getWidth(), sourceBitmap.getHeight(), CvType.CV_8UC3);
    Utils.bitmapToMat(sourceBitmap, sourceMat);

    Mat roiTmp = sourceMat.clone();
    bitmapWidth = sourceBitmap.getWidth();
    Log.e("bitmapWidth", "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    final Mat hsvMat = new Mat();
    sourceMat.copyTo(hsvMat);

    // convert mat to HSV format for Core.inRange()
    Imgproc.cvtColor(hsvMat, hsvMat, Imgproc.COLOR_RGB2HSV);

    Scalar lowerb = new Scalar(85, 50, 40);         // lower color border for BLUE
    Scalar upperb = new Scalar(135, 255, 255);      // upper color border for BLUE

    Scalar lowerblack = new Scalar(0, 0, 0);         // lower color border for BLACK
    Scalar upperblack = new Scalar(180, 255, 40);      // upper color border for BLACK

    Scalar testRunL = new Scalar(60, 50, 40); // lower Green   83 100 51
    Scalar testRunU = new Scalar(90, 255, 255); // upper Green

    Core.inRange(hsvMat, lowerblack, upperblack, roiTmp);   // select only blue pixels
    // find contours
    List<MatOfPoint> contours = new ArrayList<>();
    List<RotatedRect> boundingRects = new ArrayList<>();
    Imgproc.findContours(roiTmp, contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);

    // find appropriate bounding rectangles
    for (MatOfPoint contour : contours) {
        MatOfPoint2f areaPoints = new MatOfPoint2f(contour.toArray());
        RotatedRect boundingRect = Imgproc.minAreaRect(areaPoints);

        double rectangleArea = boundingRect.size.area();

        // test min ROI area in pixels
        if (rectangleArea > 1300 ) {
            Point rotated_rect_points[] = new Point[4];
            boundingRect.points(rotated_rect_points);
            Rect rect3 = Imgproc.boundingRect(new MatOfPoint(rotated_rect_points));


            // test horizontal ROI orientation
            if (rect3.height > rect3.width) {
                Log.e("w,h", String.valueOf(rect3.width)+ " h " + String.valueOf(rect3.height));
                double w = rect3.width;
                double h = rect3.height;
                double ratio= h/w;

                    Log.e("h:w ratio", String.valueOf(ratio));
                    Log.e("Black Area", String.valueOf(rect3.area()));
                    Imgproc.rectangle(sourceMat, rect3.tl(), rect3.br(), green, 3);
                    rectBlack = rect3;
                    Log.e("blackArea", String.valueOf(rect3.area()));
                    xBlack = rect3.br().x;
                    xBlackCenter = (rect3.br().x + rect3.tl().x) / 2;
                    yBlack = rect3.br().y;//bottom
                    battHeight = (rect3.br().y - rect3.tl().y); //batt height in pixel


            }

        }

    }

Answer 1

您可以创建矩形列表:

List<Rect> rects = new ArrayList<>();

然后在您的for (MatOfPoint轮廓:轮廓)循环中将每个建立的矩形添加到该列表中:

// find appropriate bounding rectangles
for (MatOfPoint contour : contours) {
    ...
    // test horizontal ROI orientation
    if (rect3.height > rect3.width) {
       ...
       rects.add(rect3)
    }
}

然后使用方法找到最底部的矩形，如下所示:

public static Rect getBottomMostRect(List<Rect> rects) {
    Rect bottomMostRect = null;

    if (rects != null && rects.size() >= 1) {
        Rect rect;
        double minY;
        int ixMinY = 0;

        rect = rects.get(ixMinY);
        minY = rect.tl().y;

        for (int ix = 1; ix < rects.size(); ix++) {
            rect = rects.get(ix);
            if (rect.tl().y < minY) {
                minY = rect.tl().y;
                ixMinY = ix;
            }
        }

        bottomMostRect = rects.get(ixMinY);
    }

    return bottomMostRect;
}

这样调用它:

Rect bottomMostRect = getBottomMostRect(rects)

或者将 getBottomMostRect() 实现直接添加到 for (MatOfPoint轮廓:轮廓) 循环中。