【练习8.5】轮廓长度计算机cvApproxPoly逼近

题目要求：

a、检测轮廓并计算轮廓长度

b、分别使用1/90,1/66,1/11,1/10做为精度参数，使用cvApproxPoly逼近，计算轮廓长度并画出结果

程序代码：

 1 // OpenCVExerciseTesting.cpp : 定义控制台应用程序的入口点。
 2 //
 3 //    string file_full_name = "D:\\Work\\Work_Programming\\Source\\Image\\OpenCVExerciseImage\\第8章\\r20.jpg";
 4
 5
 6 #include "stdafx.h"
 7 #include<string>
 8 #include <cv.h>
 9 #include <highgui.h>
10 #include <iostream>
11 #include<math.h>
12
13 #include <opencv2/legacy/legacy.hpp>
14 //#pragma comment(lib, "opencv_legacy2411.lib")
15
16 using namespace cv;
17 using namespace std;
18
19 //函数声明-->--->-->--->-->--->-->--->//
20
21
22 //<--<--<--<--<--<--<--<--<--函数声明//
23
24 int _tmain(int argc, _TCHAR* argv[])
25 {
26     string file_full_name = "D:\\Work\\Work_Programming\\Source\\Image\\OpenCVExerciseImage\\第8章\\r20.jpg";
27
28     IplImage * image_source = cvLoadImage(file_full_name.c_str(), CV_LOAD_IMAGE_GRAYSCALE);
29     CV_Assert(image_source);
30
31     IplImage * image_binary = cvCloneImage(image_source);
32     cvZero(image_binary);
33
34     cvThreshold(image_source, image_binary, 125, 255, CV_THRESH_BINARY);
35
36     CvMemStorage *storage = cvCreateMemStorage();
37     CvSeq* first_contour=NULL;
38     int contour_num;
39     contour_num = cvFindContours(image_binary, storage, &first_contour, sizeof(CvContour), CV_RETR_LIST);
40
41     cout << "轮廓数" << contour_num << endl;
42
43     double contour_length;
44     //for (CvSeq * c = first_contour; c != NULL; c = c->h_next)
45     //{
46     //    contour_length = cvContourPerimeter(c);
47     //    cout << "周长" << contour_length << endl;
48     //}
49     contour_length = cvContourPerimeter(first_contour);
50     cout << "周长" << contour_length << endl;
51
52     double perimeter = 126.7;
53     double parameters[4] = { 126.7 / 90, 126.7 / 66, 126.7 / 11, 126.7 / 10 };
54     CvMemStorage* storage_approx = cvCreateMemStorage();
55
56     IplImage *image_approx = cvCloneImage(image_binary);
57     cvZero(image_approx);
58     CvSeq *seq_approx=NULL;
59
60     string window_name = "Approx窗口";;
61     for (int i = 0; i < 4; ++i)
62     {
63         seq_approx = cvApproxPoly(first_contour, sizeof(CvContour), storage_approx, CV_POLY_APPROX_DP, parameters[i], 0);
64         contour_length = cvContourPerimeter(seq_approx);
65         cout << contour_length << endl;
66         window_name = window_name + ".";
67         cvDrawContours(image_approx, seq_approx, cvScalar(255), cvScalar(125), 0);
68         cvShowImage(window_name.c_str(), image_approx);
69     }
70
71     cvWaitKey(0);
72
73     cvReleaseImage(&image_source);
74     cvReleaseImage(&image_binary);
75     cvReleaseImage(&image_approx);
76     cvDestroyAllWindows();
77
78     return 0;
79 }

结果图片：

要言妙道：

借鉴参考：