如何在opencv或emgu cv中检测三角形边缘? [英] How to detect triangle edge in opencv or emgu cv?

问题描述

我正在使用Emgu CV，我想检测图片中的两个锐度，首先将图像转换为灰色，然后调用cvCanny，然后调用FindContours，但是只找到一个轮廓，找不到三角形.

I am using Emgu CV, i want to detect two sharp in the picture, first i convert the image to gray,and call cvCanny, then call FindContours， but just one contour found, the triangle not found.

代码:

 public static void Do(Bitmap bitmap, IImageProcessingLog log)
    {
        Image<Bgr, Byte> img = new Image<Bgr, byte>(bitmap);
        Image<Gray, Byte> gray = img.Convert<Gray, Byte>();
        using (Image<Gray, Byte> canny = new Image<Gray, byte>(gray.Size))
        using (MemStorage stor = new MemStorage())
        {
            CvInvoke.cvCanny(gray, canny, 10, 5, 3);
            log.AddImage("canny",canny.ToBitmap());

            Contour<Point> contours = canny.FindContours(
             Emgu.CV.CvEnum.CHAIN_APPROX_METHOD.CV_CHAIN_APPROX_SIMPLE,
             Emgu.CV.CvEnum.RETR_TYPE.CV_RETR_TREE,
             stor);

            for (int i=0; contours != null; contours = contours.HNext)
            {
                i++;
                MCvBox2D box = contours.GetMinAreaRect();

                Image<Bgr, Byte> tmpImg = img.Copy();
                tmpImg.Draw(box, new Bgr(Color.Red), 2);
                log.AddMessage("contours" + (i) +",angle:"+box.angle.ToString() + ",width:"+box.size.Width + ",height:"+box.size.Height);
                log.AddImage("contours" + i, tmpImg.ToBitmap());
            }
        }
    }

推荐答案

(我不知道emguCV，但我会告诉你的想法)

(I don't know emguCV, but i will give you the idea)

您可以按照以下步骤进行操作:

You can do it as follows:

1. 使用split()功能将图像分割为R，G，B平面.
2. 对于每个平面，应用Canny边缘检测.
3. 然后在其中找到轮廓，并使用approxPolyDP函数逼近每个轮廓.
4. 如果近似轮廓中的坐标数为3，则很可能是三角形，并且该值对应于三角形的3个顶点.

1. Split the image to R,G,B planes using split() function.
2. For each plane, apply Canny edge detection.
3. Then find the contours in it and approximate each contour using approxPolyDP function.
4. if number of coordinates in the approximated contour is 3, it is most likely a triangle and the values corresponds to 3 vertices of triangles.

下面是python代码:

Below is the python code :

import numpy as np
import cv2

img = cv2.imread('softri.png')

for gray in cv2.split(img):
    canny = cv2.Canny(gray,50,200)

    contours,hier = cv2.findContours(canny,1,2)
    for cnt in contours:
        approx = cv2.approxPolyDP(cnt,0.02*cv2.arcLength(cnt,True),True)
        if len(approx)==3:
            cv2.drawContours(img,[cnt],0,(0,255,0),2)
            tri = approx

for vertex in tri:
    cv2.circle(img,(vertex[0][0],vertex[0][1]),5,255,-1)

cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

下面是蓝色平面的canny图:

Below is canny diagram of blue color plane:

下面是最终输出，三角形及其顶点分别用绿色和蓝色标记:

Below is the final output, triangle and its vetices are marked in green and blue colors respectively:

这篇关于如何在opencv或emgu cv中检测三角形边缘?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！