選擇角點

之前用到過對一幅圖提取角點，有時候角點數目很多而且隨機生成，但是自己又想到的目標位置處的角點，這就要求有一種方法能夠把幾個角點的位置標識出來，下面程序的主要思路是：首先提取出圖中所有的角點，然後手動選擇需要的角點，最後得到角點的位置。

#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/opencv.hpp>
#include<cv.h>
#include<highgui.h>
using namespace cv;
using namespace std;


CvPoint pt1 = Point(0, 0);
CvPoint pt2 = Point(0, 0);
bool is_selecting = false;
//這個函數用來讀取鼠標畫出的方框
void cvMouseCallback(int mouseEvent, int x, int y, int flags, void* param)
{
    switch (mouseEvent)
    {
        case CV_EVENT_LBUTTONDOWN:
            pt1 = Point(x, y);
            pt2 = Point(x, y);
            is_selecting = true;
            break;
        case CV_EVENT_MOUSEMOVE:
            if (is_selecting)
                pt2 = Point(x, y);
            break;
        case CV_EVENT_LBUTTONUP:
            pt2 = Point(x, y);
            is_selecting = false;
            break;
     }
}


int main()
{
IplImage* orig = cvLoadImage("1.png");


//提取所有角點並顯示；
IplImage* gray = cvCreateImage(cvGetSize(orig), IPL_DEPTH_8U, 1);
cvCvtColor(orig, gray, CV_BGR2GRAY);
IplImage* img_temp = cvCreateImage(cvGetSize(gray), 32, 1);
IplImage* img_eigen = cvCreateImage(cvGetSize(gray), 32, 1);
int count = 1000;//the maximum numbers of points;
CvPoint2D32f* corners = new CvPoint2D32f[count];
cvGoodFeaturesToTrack(gray, img_eigen, img_temp, corners, &count, 0.1, 10);
cout << "總共角點："<<count << endl;
for (int i = 0; i<count; i++)//在原圖中顯示所有角點；
{
cout << "NO. " << i << " point :" << corners[i].x << ";" <<
corners[i].y << endl;
cvLine(orig, cvPoint(corners[i].x, corners[i].y), cvPoint(corners[i].x,
corners[i].y), CV_RGB(255, 0, 0), 5);
}
cvNamedWindow("point");
cvShowImage("point", orig);
//cvWaitKey(0);

//選擇需要角點，使用鼠標在原圖中畫小方框，以方框右下角的點作爲目標角點；
IplImage* img_show = cvCreateImage(cvGetSize(orig), IPL_DEPTH_8U, 3);
CvPoint2D32f pos[4];//存儲四個目標角點座標；
setMouseCallback("point", cvMouseCallback);
bool shift_on = false;
for (int i = 0; i < 4; i++){//這裏假設需要圖中四個角處的角點
while (true)
{
cvCopy(orig, img_show);
cvRectangle(img_show, pt1, pt2, Scalar(0, 255, 0));
char key = cvWaitKey(10);
cvSetImageROI(img_show, cvRect(pt1.x, pt1.y, abs(pt2.x - pt1.x), abs(pt2.y - pt1.y)));
IplImage* roi = cvCreateImage(cvSize(abs(pt2.x - pt1.x), abs(pt2.y - pt1.y)), IPL_DEPTH_8U, 3);
cvCopy(img_show, roi);
cvResetImageROI(img_show);
if (key == 27) break;//按下Esc表示一個角點選擇完畢；
}
pos[i] = cvPointTo32f(pt2);
cout <<"角點座標：" <<pos[i].x << " , " << pos[i].y << endl;
}


cvWaitKey(0);
return 0;
}