c++ - opencv 3.0 findContours 函数在窗口中不起作用

Question

我正在使用 visual studio 15 并在 opencv 3.0 中工作，我的代码中出现访问冲突错误，甚至这个函数也不适用于 opencv 中给出的示例代码。

#include"stdafx.h"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <math.h>
#include <iostream>

using namespace cv;
using namespace std;

static void help()
{
    cout
        << "\nThis program illustrates the use of findContours and drawContours\n"
        << "The original image is put up along with the image of drawn contours\n"
        << "Usage:\n"
        << "./contours2\n"
        << "\nA trackbar is put up which controls the contour level from -3 to 3\n"
        << endl;
}

const int w = 500;
int levels = 3;

vector<vector<Point> > contours;
vector<Vec4i> hierarchy;

static void on_trackbar(int, void*)
{
    Mat cnt_img = Mat::zeros(w, w, CV_8UC3);
    int _levels = levels - 3;
    drawContours(cnt_img, contours, _levels <= 0 ? 3 : -1, Scalar(128, 255, 255),
        3, LINE_AA, hierarchy, std::abs(_levels));

    imshow("contours", cnt_img);
}

int main(int argc, char**)
{
    Mat img = Mat::zeros(w, w, CV_8UC1);
    if (argc > 1)
    {
        help();
        return -1;
    }
    //Draw 6 faces
    for (int i = 0; i < 6; i++)
    {
        int dx = (i % 2) * 250 - 30;
        int dy = (i / 2) * 150;
        const Scalar white = Scalar(255);
        const Scalar black = Scalar(0);

        if (i == 0)
        {
            for (int j = 0; j <= 10; j++)
            {
                double angle = (j + 5)*CV_PI / 21;
                line(img, Point(cvRound(dx + 100 + j * 10 - 80 * cos(angle)),
                    cvRound(dy + 100 - 90 * sin(angle))),
                    Point(cvRound(dx + 100 + j * 10 - 30 * cos(angle)),
                        cvRound(dy + 100 - 30 * sin(angle))), white, 1, 8, 0);
            }
        }

        ellipse(img, Point(dx + 150, dy + 100), Size(100, 70), 0, 0, 360, white, -1, 8, 0);
        ellipse(img, Point(dx + 115, dy + 70), Size(30, 20), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 185, dy + 70), Size(30, 20), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 115, dy + 70), Size(15, 15), 0, 0, 360, white, -1, 8, 0);
        ellipse(img, Point(dx + 185, dy + 70), Size(15, 15), 0, 0, 360, white, -1, 8, 0);
        ellipse(img, Point(dx + 115, dy + 70), Size(5, 5), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 185, dy + 70), Size(5, 5), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 150, dy + 100), Size(10, 5), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 150, dy + 150), Size(40, 10), 0, 0, 360, black, -1, 8, 0);
        ellipse(img, Point(dx + 27, dy + 100), Size(20, 35), 0, 0, 360, white, -1, 8, 0);
        ellipse(img, Point(dx + 273, dy + 100), Size(20, 35), 0, 0, 360, white, -1, 8, 0);
    }
    //show the faces
    namedWindow("image", 1);
    imshow("image", img);
    //Extract the contours so that
    //vector<vector<Point> > contours0;
    vector<cv::Mat> coutours;
    findContours(img, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE);

    contours.resize(contours.size());
    for (size_t k = 0; k < contours.size(); k++)
        approxPolyDP(Mat(contours[k]), contours[k], 3, true);

    namedWindow("contours", 1);
    createTrackbar("levels+3", "contours", &levels, 7, on_trackbar);

    on_trackbar(0, 0);
    waitKey();

    return 0;
}

我正在使用 x64 架构并将所有库 .lib 与 d.lib(调试库)链接起来。

Answer 1

我认为问题出在您的“轮廓”变量上。您将其声明为 vector<cv::Mat> ，但轮廓不是表示为矩阵，而是表示为一系列点。

看这个例子:http://docs.opencv.org/2.4/doc/tutorials/imgproc/shapedescriptors/find_contours/find_contours.html

他们将轮廓声明为 vector<vector<Point> > contours;

再看看函数的声明(http://docs.opencv.org/2.4/modules/imgproc/doc/structural_analysis_and_shape_descriptors.html?highlight=findcontours#findcontours)，参数轮廓定义为:contours – Detected contours. Each contour is stored as a vector of points.