为什么等高线面积只返回0

Question

我试图找到轮廓面积，但轮廓面积只返回0不管等高线是什么。没有错误显示。

void CMFC_DEMODlg::OnBnClickedRun()
{
    CString str;
    IplImage* src1    = cvLoadImage("onlyone001.JPG",1);
    IplImage* src2    = cvLoadImage("b004.JPG",1);
    IplImage* grey    = cvCreateImage( cvGetSize(src2), 8, 1 );
    IplImage* dst    = cvCreateImage( cvGetSize(src2), 8, 3 );
    IplImage* F        = cvCreateImage( cvGetSize(src2), 8, 1 );
    IplImage* W        = cvCreateImage( cvGetSize(src2), 8, 1 );
    cvCvtColor( src2, grey, CV_BGR2GRAY);
    cvThreshold( grey, W,200,255,CV_THRESH_BINARY);
    CvSeq* c;
    CvSeq* contour;
    CvSeq* result;
    CvMemStorage* storage = cvCreateMemStorage(0);
    int Nc = cvFindContours(
    W,
    storage,
    &contour,
    sizeof(CvContour),
    CV_RETR_LIST,
    CV_CHAIN_APPROX_SIMPLE,
    cvPoint(0,0));
    double Area;
    result = cvApproxPoly(contour, sizeof(CvContour), storage,
        CV_POLY_APPROX_DP, cvContourPerimeter(contour)*0.02, 0);
    Area = fabs(cvContourArea(result, CV_WHOLE_SEQ));
    str.Format("Area: %dn", Area);
    GetDlgItem(IDC_STATIC02)->SetWindowText(str);
    str.Format("Nc: %dn", Nc);
    GetDlgItem(IDC_STATIC01)->SetWindowText(str);

    m_CvvImage.CopyOf(src2,1);
    m_CvvImage.DrawToHDC(Disp_hDC1,Disp_Rect);
    m_CvvImage.CopyOf(src1,1);
    m_CvvImage.DrawToHDC(Disp_hDC2,Disp_Rect);
    m_CvvImage.CopyOf(W,1);
    m_CvvImage.DrawToHDC(Disp_hDC3,Disp_Rect);
}

我只是想计算图像中每个轮廓的面积。我做错了什么?

Answer 1

点应按顺时针顺序放置在向量中。以正方形为例:

corners2.push_back(Point(0,0));
corners2.push_back(Point(src.rows-1,0));
corners2.push_back(Point(src.rows-1,src.cols-1));
corners2.push_back(Point(1,src.cols-1));