在emgucv中查找轮廓点

Question

我正在使用emguCV查找轮廓基本点，然后将此点保存在文件中，用户将来重新绘制此形状。所以，我的目标是这个形象：

example

我的解决方案是：1。将图像导入到图片框2.使用canny算法进行边缘检测3.找到轮廓并保存点

我在下面的代码中找到了很多分，但是我不能用这一点绘制第一个形状！

using Emgu.CV;
using Emgu.Util;

private void button1_Click(object sender, EventArgs e)

{
            Bitmap bmp = new Bitmap(pictureBox1.Image);
            Image<Bgr, Byte> img = new Image<Bgr, byte>(bmp);

            Image<Gray, Byte> gray = img.Convert<Gray, Byte>().PyrDown().PyrUp();

            Gray cannyThreshold = new Gray(80);
            Gray cannyThresholdLinking = new Gray(120);
            Gray circleAccumulatorThreshold = new Gray(120);

            Image<Gray, Byte> cannyEdges = gray.Canny(cannyThreshold, cannyThresholdLinking).Not();

            Bitmap color;
            Bitmap bgray;
            IdentifyContours(cannyEdges.Bitmap, 50, true, out bgray, out color);

            pictureBox1.Image = color;
        }

        public void IdentifyContours(Bitmap colorImage, int thresholdValue, bool invert, out Bitmap processedGray, out Bitmap processedColor)
        {
            Image<Gray, byte> grayImage = new Image<Gray, byte>(colorImage);
            Image<Bgr, byte> color = new Image<Bgr, byte>(colorImage);

            grayImage = grayImage.ThresholdBinary(new Gray(thresholdValue), new Gray(255));

            if (invert)
            {
                grayImage._Not();
            }

            using (MemStorage storage = new MemStorage())
            {

                for (Contour<Point> contours = grayImage.FindContours(Emgu.CV.CvEnum.CHAIN_APPROX_METHOD.CV_CHAIN_APPROX_SIMPLE, Emgu.CV.CvEnum.RETR_TYPE.CV_RETR_LIST, storage); contours != null; contours = contours.HNext)
                {

                    Contour<Point> currentContour = contours.ApproxPoly(contours.Perimeter * 0.015, storage);
                    if (currentContour.BoundingRectangle.Width > 20)
                    {
                        CvInvoke.cvDrawContours(color, contours, new MCvScalar(255), new MCvScalar(255), -1, 1, Emgu.CV.CvEnum.LINE_TYPE.EIGHT_CONNECTED, new Point(0, 0));
                        color.Draw(currentContour.BoundingRectangle, new Bgr(0, 255, 0), 1);
                    }

                    Point[] pts = currentContour.ToArray();
                    foreach (Point p in pts)
                    {
                        //add points to listbox
                        listBox1.Items.Add(p);
                    }
                }
            }

            processedColor = color.ToBitmap();
            processedGray = grayImage.ToBitmap();

        }

Answer 1

在您的代码中，您添加了轮廓近似操作

Contour<Point> currentContour = contours.ApproxPoly(contours.Perimeter * 0.015, storage);

这个轮廓近似将approximate your Contour到nearest polygon，所以你的实际点被移动了。如果要重现相同的图像，则无需进行任何近似。

Refer this thread.