使用OpenCV和C++查找沿轮廓点的坐标

Question

我是使用OpenCV和C++的新手，我已经处理图片并提取图片中的轮廓。然后我在一个新的黑色框架上绘制轮廓。具体来说，我绘制了红色的轮廓。我想获得黑框中每个和所有红色像素的坐标并将其存储在一个数组中。我需要这方面的帮助，代码是首选。提前致谢。

这里是我的代码：

#include <iostream> 
#include <Windows.h> 
#include <sstream> 

#include <opencv2/opencv.hpp> 
#include <opencv2\core\core.hpp> 
#include <opencv2\highgui\highgui.hpp> 
#include <opencv2\imgproc\imgproc.hpp> 
#include <opencv2/objdetect/objdetect.hpp> 

using namespace cv; 
using namespace std; 

void on_trackbar(int, void*); 
void createTrackbars(); 
void toggle(int); 

const int MAX_NUM_OBJECTS = 500; 

const int FRAME_WIDTH = 900; 
const int FRAME_HEIGHT = 600; 

const int MIN_OBJECT_AREA = 20 * 20; 
const int MAX_OBJECT_AREA = FRAME_HEIGHT*FRAME_WIDTH/1.5; 

Point middle; 

int l_MIN = 30; 
int l_MAX = 165; 
int a_MIN = 139; 
int a_MAX = 165; 
int b_MIN = 136; 
int b_MAX = 172; 

int kerode = 2; 
int kdilate = 8; 

bool showchangedframe = true; 

int main(int argc, char** argv) 
{ 
    createTrackbars(); 
    on_trackbar(0, 0); 

    int x, y; 
    Mat frame, labframe, rangeframe; 
    Mat newframe, newrf; 
    int key; 

    while ((key = waitKey(30)) != 27) 
    { 
     toggle(key); 
     frame = imread(argv[1], 1); 
     newframe = imread(argv[1], 1); 
     dframe = imread(argv[1], 1); 
     newframe = Scalar(0, 0, 0); 
     dframe = Scalar(0, 0, 0); 
     cvtColor(frame, labframe, COLOR_BGR2Lab); 
     inRange(labframe, Scalar(l_MIN, a_MIN, b_MIN), Scalar(l_MAX, a_MAX, b_MAX), rangeframe); 

     erode(rangeframe, rangeframe, getStructuringElement(MORPH_RECT, Size(kerode, kerode))); 
     dilate(rangeframe, rangeframe, getStructuringElement(MORPH_RECT, Size(kdilate, kdilate))); 

     newrf = rangeframe.clone(); 

     int largest_area = 0; 
     int largest_contour_index = 0; 
     vector<vector<Point> > contours; 

     findContours(newrf, contours, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE); 

     vector<Moments> mu(contours.size()); //get moments 
     for (int i = 0; i < contours.size(); i++) 
     { 
      mu[i] = moments(contours[i], false); 
     } 

     vector<Point2f> mc(contours.size()); //get centers 
     for (int i = 0; i < contours.size(); i++) 
     { 
      mc[i] = Point2f(mu[i].m10/mu[i].m00, mu[i].m01/mu[i].m00); 
     } 

     for (int i = 0; i < contours.size(); i++) //iterate through each contour. 
     { 
      double a = contourArea(contours[i], false); //Find the area of contour 

      if (a>largest_area) 
      { 
       largest_area = a; 
       largest_contour_index = i; //Store the index of largest contour 
      } 
     } 

     drawContours(newframe, contours, largest_contour_index, CV_RGB(255, 0, 0), 4); 
     circle(newframe, mc[largest_contour_index], 5, CV_RGB(255, 255, 0), -1, 8, 0); 

     imshow("Detected", newframe); 

     if (showchangedframe) 
      imshow("Camera", frame); 
     else 
      imshow("Camera", rangeframe); 
    } 
} 

void on_trackbar(int, void*) 
{ 
    if (kerode == 0) 
     kerode = 1; 
    if (kdilate == 0) 
     kdilate = 1; 
} 

void createTrackbars() 
{ 
    String trackbarWindowName = "TrackBars"; 
    namedWindow(trackbarWindowName, WINDOW_NORMAL); 
    createTrackbar("l_MIN", trackbarWindowName, &l_MIN, l_MAX, on_trackbar); 
    createTrackbar("l_MAX", trackbarWindowName, &l_MAX, l_MAX, on_trackbar); 
    createTrackbar("a_MIN", trackbarWindowName, &a_MIN, a_MAX, on_trackbar); 
    createTrackbar("a_MAX", trackbarWindowName, &a_MAX, a_MAX, on_trackbar); 
    createTrackbar("b_MIN", trackbarWindowName, &b_MIN, b_MAX, on_trackbar); 
    createTrackbar("b_MAX", trackbarWindowName, &b_MAX, b_MAX, on_trackbar); 
    createTrackbar("Erosion", trackbarWindowName, &kerode, 31, on_trackbar); 
    createTrackbar("Dilation", trackbarWindowName, &kdilate, 31, on_trackbar); 
} 

void toggle(int key) 
{ 
    if (key == 'r') 
     showchangedframe = !showchangedframe; 
} 

这里是输出：

Answer 1

替代由CV_CHAIN_APPROX_NONE CV_CHAIN_APPROX_SIMPLE（见DOC），以获得在findContours结果每一个轮廓点。

apörox_simple通过用起点和终点替换直线部分来减少轮廓点的数量。 approx_none根本不会减少轮廓点的数量。

的地方与你

vector<vector<Point> > contours 

您可以通过访问它们：

for (size_t cC = 0; cC < contours.size(); ++cC) 
    for(size_t cP =0; cP < contours[cC].size(); cP++) 
    { 
     Point currentContourPixel = contours[cC][cP]; 
     // do whatever you want 
    }