OpenCV cvFindContours只找到一个轮廓

Question

我继续使用openCV工作，这是我描述的第一次冒险here。它进展顺利，但我偶然发现了另一件棘手的事情。我想在图像上找到轮廓，我已将自适应阈值应用于：

所以cvFindContours似乎工作得很好，结果如下：

问题是，当我尝试迭代找到的countours时，它说只有一个轮廓（以下代码中的contours->total等于1）。这是代码：

IplImage* img;
if((img = cvLoadImage( "photos/img-000012.ppm", 1)) == 0 )
{
    perror("cvLoadImage");
    return 1;
}
cvNamedWindow( "Image view", 1 );
cvShowImage( "Image view", img );

IplImage* gray = cvCreateImage( cvGetSize(img), 8, 1 ); // allocate a 1 channel byte image
cvCvtColor( img, gray, CV_BGR2GRAY );
cvShowImage( "Image view", gray );
cvWaitKey(0);

cvAdaptiveThreshold(gray, gray,
        255,    //  Non-zero value assigned to the pixels for which the condition is satisfied
        CV_ADAPTIVE_THRESH_MEAN_C, // adaptiveMethod
        CV_THRESH_BINARY_INV,   // thresholdType
        11, // blockSize
        5); // Constant subtracted from the mean or weighted mean
cvShowImage( "Image view", gray );
cvWaitKey(0);

IplConvKernel *se = cvCreateStructuringElementEx(3, 3, 1,  1,  CV_SHAPE_RECT, NULL);
cvErode(gray, gray, se, 1);
cvShowImage( "Image view", gray );
cvWaitKey(0);

IplImage *canny_out = cvCreateImage(cvGetSize(gray), 8, 1);
cvCanny(gray, canny_out, 50, 100, 3);
cvShowImage( "Image view", canny_out );
cvWaitKey(0);

CvMemStorage *storage = cvCreateMemStorage(0);
CvSeq *contours = cvCreateSeq(0, sizeof(CvSeq), sizeof(CvPoint), storage);
cvFindContours(gray, storage, &contours, sizeof(CvContour), CV_RETR_LIST,
        CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0));
printf("contours->total = %d\n", contours->total);

cvDrawContours(img, contours, CV_RGB(0,255,0), CV_RGB(0,0,255),
        2, 1, 8, cvPoint(0, 0));
cvShowImage( "Image view", img );
cvWaitKey(0);

是不是这样，只有一个轮廓？也许我不了解openCV对轮廓的定义？我很感激你的帮助。

Answer 1

实际上cvFindContours会返回已创建轮廓的数量（我测试了您的图片并返回＆gt; 1）。见docs。但我不知道为什么total等于一个。

Answer 2

1. cvCreateSeq()
之前您不需要cvFindContours()

2. 而不是contours-＆gt; total，遍历它们。

   for (; contours != 0; contours = contours->h_next)