Surf特征点检测与匹配代码分析

1. #include <opencv2\core\core.hpp>  
2. #include <opencv2\highgui\highgui.hpp>  
3. #include <opencv2\nonfree\features2d.hpp>  
4. #include <opencv2\nonfree\nonfree.hpp>  
5. #include <opencv2\calib3d\calib3d.hpp>  
6. #include <iostream>  
7.   
8. using namespace std;  
9. using namespace cv;  
10.   
11. vector<DMatch> ransac(vector<KeyPoint> queryKeyPoint,vector<KeyPoint> trainKeyPoint,vector<DMatch> matches);  
12.   
13.   
14. int main(int argc,char* argv[])  
15. {  
16.     //定义图像  
17.     Mat queryImage,trainImage;  
18.       
19.     //读取图像  
20.     queryImage = imread("3.jpg",IMREAD_COLOR);  
21.     trainImage = imread("4.jpg",IMREAD_COLOR);  
22.     //判断是否读取图像  
23.     if(queryImage.empty() || trainImage.empty())  
24.     {  
25.         cerr<<"Failure in loading image"<<endl;  
26.         return -1;  
27.     }  
28.   
29.     //定义Surf特征检测器  
30.     SurfFeatureDetector surfDetector;  
31.   
32.     //定义特征点  
33.     vector<KeyPoint> queryKeyPoint,trainKeyPoint;  
34.   
35.     //检测surf特征  
36.     surfDetector.detect(queryImage,queryKeyPoint);  
37.     surfDetector.detect(trainImage,trainKeyPoint);  
38.   
39.     //查看检测到的特征点的数目  
40.     cout<<"Number of queryKeyPoint:"<<queryKeyPoint.size()<<endl;  
41.     cout<<"Number of trainKeyPoint:"<<trainKeyPoint.size()<<endl;  
42.   
43.     //定义绘制surf特征点的图像  
44.     Mat queryImageKeyPoint,trainImageKeyPoint;  
45.   
46.     //绘制surf特征点  
47.     drawKeypoints(queryImage,queryKeyPoint,queryImageKeyPoint,Scalar(0,0,255),  
48.         /*DrawMatchesFlags::DRAW_RICH_KEYPOINTS*/DrawMatchesFlags::DEFAULT);  
49.     drawKeypoints(trainImage,trainKeyPoint,trainImageKeyPoint,Scalar(0,0,255),  
50.         /*DrawMatchesFlags::DRAW_RICH_KEYPOINTS*/DrawMatchesFlags::DEFAULT);  
51.   
52.     //定义显示窗口，可不要  
53.     namedWindow("queryImageKeyPoint",CV_WINDOW_AUTOSIZE);  
54.     namedWindow("trainImageKeyPoint",CV_WINDOW_AUTOSIZE);  
55.   
56.     //显示surf特征点  
57.     imshow("queryImageKeyPoint",queryImageKeyPoint);  
58.     imshow("trainImageKeyPoint",trainImageKeyPoint);  
59.   
60.     //定义surf特征描述子  
61.     Mat queryDescriptor,trainDescriptor;  
62.   
63.     //定义Surf特征描述子提取器  
64.     SurfDescriptorExtractor surfExtractor;  
65.   
66.     //提取特征描述子  
67.     surfExtractor.compute(queryImage,queryKeyPoint,queryDescriptor);  
68.     surfExtractor.compute(trainImage,trainKeyPoint,trainDescriptor);  
69.       
70.     //定义描述子匹配对  
71.     vector<DMatch> bfMatches;  
72.     vector<DMatch> flannMatches;  
73.   
74.     //Brute Match，穷举法求最近邻  
75.     BFMatcher bfMatcher;  
76.     bfMatcher.match(queryDescriptor,trainDescriptor,bfMatches);  
77.   
78.     //FlannBasedMatcher，最近邻近似匹配  
79.     FlannBasedMatcher flannMatcher;  
80.     flannMatcher.match(queryDescriptor,trainDescriptor,flannMatches);  
81.   
82.   
83.     //对匹配点进行RANSAC过滤  
84.     vector<DMatch> ransac_BFMatches,ransac_FlannMatches;  
85.   
86.     ransac_BFMatches=ransac(queryKeyPoint,trainKeyPoint,bfMatches);  
87.     ransac_FlannMatches=ransac(queryKeyPoint,trainKeyPoint,flannMatches);  
88.   
89.     //定义匹配图像  
90.     Mat bfMatchImage,flannMatchImage;  
91.   
92.     //绘制匹配图像  
93.     //drawMatches(queryImage,queryKeyPoint,trainImage,trainKeyPoint,bfMatches,bfMatchImage);  
94.     //drawMatches(queryImage,queryKeyPoint,trainImage,trainKeyPoint,flannMatches,flannMatchImage);  
95.     drawMatches(queryImage,queryKeyPoint,trainImage,trainKeyPoint,ransac_BFMatches,bfMatchImage);  
96.     drawMatches(queryImage,queryKeyPoint,trainImage,trainKeyPoint,ransac_FlannMatches,flannMatchImage);  
97.       
98.     //显示匹配结果  
99.     imshow("BFMatch",bfMatchImage);  
100.     imshow("FlannMatch",flannMatchImage);  
101.   
102.   
103.     waitKey(0);  
104.     return 0;  
105. }  
106.   
107. vector<DMatch> ransac(vector<KeyPoint> queryKeyPoint,vector<KeyPoint> trainKeyPoint,vector<DMatch> matches)  
108. {  
109.     cout<<"ransac前："<<matches.size()<<endl;  
110.     vector<Point2f> queryPoints(matches.size()),trainPoints(matches.size());  
111.     for(int i=0;i<matches.size();i++)  
112.     {  
113.         queryPoints[i] = queryKeyPoint[matches[i].queryIdx].pt;   
114.         trainPoints[i] = trainKeyPoint[matches[i].trainIdx].pt;   
115.     }  
116.   
117.     Mat H;  
118.     vector<unsigned char> inlierMask(matches.size());  
119.     vector<DMatch> ransac_matches;  
120.     H = findHomography(queryPoints,trainPoints,CV_RANSAC,3,inlierMask);  
121.   
122.     for(int i=0;i<inlierMask.size();i++)  
123.     {  
124.         if(inlierMask[i])  
125.         {  
126.             ransac_matches.push_back(matches[i]);  
127.         }  
128.     }  
129.     cout<<"ransac后："<<ransac_matches.size()<<endl;  
130.     return ransac_matches;  
131. }  

SURF原理：http://blog.youkuaiyun.com/quincuntial/article/details/50461274

转载自：http://blog.youkuaiyun.com/quincuntial/article/details/50132089