Question

我试图通过为每个帧调用SURF函数来查找视频中的对象... 这是SURF功能 {

void Identify_SURF_Frame (Mat img_object , Mat img_scene , CvRect in_box) 
{ 
//-- Step 1: Detect the keypoints using SURF Detector
int minHessian = 1;
SurfFeatureDetector detector( minHessian , 15 , 3 );
std::vector<KeyPoint> keypoints_object, keypoints_scene;
detector.detect( img_object, keypoints_object );
detector.detect( img_scene, keypoints_scene );

//-- Step 2: Calculate descriptors (feature vectors)
SurfDescriptorExtractor extractor;
Mat descriptors_object, descriptors_scene;
extractor.compute( img_object, keypoints_object, descriptors_object );
extractor.compute( img_scene, keypoints_scene, descriptors_scene );

//-- Step 3: Matching descriptor vectors using FLANN matcher
//FlannBasedMatcher matcher;
BruteForceMatcher < L2 < float > > matcher;
//BFMatcher matcher( cv::NORM_L2SQR , false );
std::vector< DMatch > matches;
matcher.match( descriptors_object, descriptors_scene, matches );
double max_dist = 0; double min_dist = 100;

//-- Quick calculation of max and min distances between keypoints
for( int i = 0; i < descriptors_object.rows; i++ )
{ 
    double dist = matches[i].distance;
    if( dist < min_dist ) min_dist = dist;
    if( dist > max_dist ) max_dist = dist;
}

//-- Draw only "good" matches (i.e. whose distance is less than 3*min_dist )
std::vector< DMatch > good_matches;
for( int i = 0; i < descriptors_object.rows; i++ )
{ 
    if( matches[i].distance < 4 * min_dist )
    { 
        good_matches.push_back( matches[i]); 
    }
}

Mat img_matches;
drawMatches( img_object, keypoints_object, img_scene, keypoints_scene, good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

//-- Localize the object
std::vector<Point2f> obj;
std::vector<Point2f> scene;
    for( int i = 0; i < good_matches.size(); i++ )
    {
        //-- Get the keypoints from the good matches
        obj.push_back( keypoints_object[ good_matches[i].queryIdx ].pt );
        scene.push_back( keypoints_scene[ good_matches[i].trainIdx ].pt );
    }

    Mat H = findHomography( obj, scene, CV_RANSAC );
    //-- Get the corners from the image_1 ( the object to be "detected" )
    std::vector<Point2f> obj_corners(2);
    obj_corners[0] = cvPoint(0,0); 
    obj_corners[1] = cvPoint( img_object.cols, 0 );
    //obj_corners[2] = cvPoint( img_object.cols, img_object.rows ); 
    //obj_corners[3] = cvPoint( 0, img_object.rows );

    std::vector<Point2f> scene_corners(2);
    perspectiveTransform( obj_corners, scene_corners, H);
    int x1 , x2 , y1 , y2 ;
    x1 = scene_corners[0].x + Point2f( img_object.cols, 0).x ; 
    y1 = scene_corners[0].y + Point2f( img_object.cols, 0).y ; 
    x2 = scene_corners[0].x + Point2f( img_object.cols, 0).x + in_box.width ; 
    y2 = scene_corners[0].y + Point2f( img_object.cols, 0).y + in_box.height ; 

    rectangle(img_matches , cvPoint(x1, y1) , cvPoint(x2, y2)  , Scalar( 255, 255, 255), 1 );
            // square is the global CvRect to use it in main 
    square.x = x1 - in_box.width ; 
    square.y = y1 ; 
    square.width = in_box.width ; 
    square.height = in_box.height ;  

//-- Show detected matches
imshow( "Good Matches & Object detection", img_matches );
}
}

使用此功能我试图在找到它时在对象周围绘制固定大小的方块问题是....有一段时间我得到了这个错误，我不是什么意思..有时程序工作正常没有这个错误..当这个错误发生时程序划痕

 {     
 OpenCV Error: Assertion failed (count >= 4) in cvFindHomography, file /Users/seereen2004/Desktop/OpenCV-2.4.3/modules/calib3d/src/fundam.cpp, line 235
 terminate called after throwing an instance of 'cv::Exception'
   what():  /Users/seereen2004/Desktop/OpenCV-2.4.3/modules/calib3d/src/fundam.cpp:235:    error: (-215) count >= 4 in function cvFindHomography

 Program received signal:  “SIGABRT”.
 sharedlibrary apply-load-rules all
 }

请问任何解释？在此先感谢

Answer 1

类似的东西可能是你的good_matches太少（＆lt; = 4）。你需要跳过这个框架。

跟踪对象时出现SURF错误

1 个答案: