转载“学习OpenCV——ORB简化版&Location加速版 ”

转自：http://blog.csdn.net/sangni007/article/details/7545820

 

根据前面surf简化版的结构，重新把ORB检测的代码给简化以下，发现虽然速度一样，确实能省好多行代码，关键是有

BruteForceMatcher<HammingLUT>matcher的帮忙，直接省的写了一个函数；

NB类型：classgpu::BruteForceMatcher_GPU

再加上findHomography，之后perspectiveTransform就可以location，但是这样速度很慢；

于是改动一下，求matches的keypoints的x与y坐标和的平均值，基本上就是对象中心！！！

以这个点为中心画与原对象大小相同的矩形框，就可以定位出大概位置，但是肯定不如透视变换准确，而且不具有尺度不变性。

但是鲁棒性应该更好，因为，只要能match成功，基本都能定位中心，但是透视变换有时却因为尺度变换过大等因素，画出很不靠谱的矩形框！

#include "opencv2/objdetect/objdetect.hpp" #include "opencv2/features2d/features2d.hpp" #include "opencv2/highgui/highgui.hpp" #include "opencv2/calib3d/calib3d.hpp" #include "opencv2/imgproc/imgproc_c.h" #include "opencv2/imgproc/imgproc.hpp"   #include <string>#include <vector>#include <iostream>using namespace cv;using namespace std; char* image_filename1 = "D:/src.jpg"; char* image_filename2 = "D:/Demo.jpg"; int main(){Mat img1 = imread( image_filename1, CV_LOAD_IMAGE_GRAYSCALE );Mat img2 = imread( image_filename2, CV_LOAD_IMAGE_GRAYSCALE );int64 st,et;ORB orb1(30,ORB::CommonParams(1.2,1));ORB orb2(100,ORB::CommonParams(1.2,1));vector<KeyPoint>keys1,keys2;Mat descriptor1,descriptor2;orb1(img1,Mat(),keys1,descriptor1,false);st=getTickCount();orb2(img2,Mat(),keys2,descriptor2,false);et=getTickCount()-st;et=et*1000/(double)getTickFrequency();cout<<"extract time:"<<et<<"ms"<<endl;vector<DMatch> matches;         //<EM>class </EM><TT class=descclassname>gpu::</TT><TT class=descname><SPAN class=highlighted>BruteForce</SPAN>Matcher_GPU</TT>BruteForceMatcher<HammingLUT>matcher;//BruteForceMatcher支持<Hamming> <L1<float>> <L2<float>>//FlannBasedMatcher matcher;不支持 st=getTickCount();matcher.match(descriptor1,descriptor2,matches);et=getTickCount()-st;et=et*1000/getTickFrequency();cout<<"match time:"<<et<<"ms"<<endl;Mat img_matches;drawMatches( img1, keys1, img2, keys2,matches, img_matches, Scalar::all(-1), Scalar::all(-1),vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );imshow("match",img_matches);cout<<"match size:"<<matches.size()<<endl;/*Mat showImg;drawMatches(img1,keys1,img2,keys2,matchs,showImg);imshow( "win", showImg ); */waitKey(0);st=getTickCount();vector<Point2f>pt1;vector<Point2f>pt2;float x=0,y=0;for(size_t i=0;i<matches.size();i++){pt1.push_back(keys1[matches[i].queryIdx].pt);pt2.push_back(keys2[matches[i].trainIdx].pt);x+=keys2[matches[i].trainIdx].pt.x;y+=keys2[matches[i].trainIdx].pt.y;}x=x/matches.size();y=y/matches.size();Mat homo;homo=findHomography(pt1,pt2,CV_RANSAC); vector<Point2f>src_cornor(4);vector<Point2f>dst_cornor(4);src_cornor[0]=cvPoint(0,0);src_cornor[1]=cvPoint(img1.cols,0);src_cornor[2]=cvPoint(img1.cols,img1.rows);src_cornor[3]=cvPoint(0,img1.rows);perspectiveTransform(src_cornor,dst_cornor,homo);Mat img=imread(image_filename2,1);line(img,dst_cornor[0],dst_cornor[1],Scalar(255,0,0),2);line(img,dst_cornor[1],dst_cornor[2],Scalar(255,0,0),2);line(img,dst_cornor[2],dst_cornor[3],Scalar(255,0,0),2);line(img,dst_cornor[3],dst_cornor[0],Scalar(255,0,0),2);/*line(img,cvPoint((int)dst_cornor[0].x,(int)dst_cornor[0].y),cvPoint((int)dst_cornor[1].x,(int)dst_cornor[1].y),Scalar(255,0,0),2);line(img,cvPoint((int)dst_cornor[1].x,(int)dst_cornor[1].y),cvPoint((int)dst_cornor[2].x,(int)dst_cornor[2].y),Scalar(255,0,0),2);line(img,cvPoint((int)dst_cornor[2].x,(int)dst_cornor[2].y),cvPoint((int)dst_cornor[3].x,(int)dst_cornor[3].y),Scalar(255,0,0),2);line(img,cvPoint((int)dst_cornor[3].x,(int)dst_cornor[3].y),cvPoint((int)dst_cornor[0].x,(int)dst_cornor[0].y),Scalar(255,0,0),2);*/circle(img,Point(x,y),10,Scalar(0,0,255),3,CV_FILLED);line(img,Point(x-img1.cols/2,y-img1.rows/2),Point(x+img1.cols/2,y-img1.rows/2),Scalar(0,0,255),2);line(img,Point(x+img1.cols/2,y-img1.rows/2),Point(x+img1.cols/2,y+img1.rows/2),Scalar(0,0,255),2);line(img,Point(x+img1.cols/2,y+img1.rows/2),Point(x-img1.cols/2,y+img1.rows/2),Scalar(0,0,255),2);line(img,Point(x-img1.cols/2,y+img1.rows/2),Point(x-img1.cols/2,y-img1.rows/2),Scalar(0,0,255),2);imshow("location",img);et=getTickCount()-st;et=et*1000/getTickFrequency();cout<<"location time:"<<et<<"ms"<<endl;waitKey(0);}