diff --git a/samples/cpp/tutorial_code/features2D/SURF_Homography.cpp b/samples/cpp/tutorial_code/features2D/SURF_Homography.cpp new file mode 100644 index 0000000000..2b87abdd48 --- /dev/null +++ b/samples/cpp/tutorial_code/features2D/SURF_Homography.cpp @@ -0,0 +1,129 @@ +/** + * @file SURF_Homography + * @brief SURF detector + descriptor + FLANN Matcher + FindHomography + * @author A. Huaman + */ + +#include +#include +#include "opencv2/core/core.hpp" +#include "opencv2/features2d/features2d.hpp" +#include "opencv2/highgui/highgui.hpp" +#include "opencv2/calib3d/calib3d.hpp" + +using namespace cv; + +void readme(); + +/** + * @function main + * @brief Main function + */ +int main( int argc, char** argv ) +{ + if( argc != 3 ) + { readme(); return -1; } + + Mat img_1 = imread( argv[1], CV_LOAD_IMAGE_GRAYSCALE ); + Mat img_2 = imread( argv[2], CV_LOAD_IMAGE_GRAYSCALE ); + + if( !img_1.data || !img_2.data ) + { std::cout<< " --(!) Error reading images " << std::endl; return -1; } + + //-- Step 1: Detect the keypoints using SURF Detector + int minHessian = 400; + + SurfFeatureDetector detector( minHessian ); + + std::vector keypoints_1, keypoints_2; + + detector.detect( img_1, keypoints_1 ); + detector.detect( img_2, keypoints_2 ); + + //-- Step 2: Calculate descriptors (feature vectors) + SurfDescriptorExtractor extractor; + + Mat descriptors_1, descriptors_2; + + extractor.compute( img_1, keypoints_1, descriptors_1 ); + extractor.compute( img_2, keypoints_2, descriptors_2 ); + + //-- Step 3: Matching descriptor vectors using FLANN matcher + FlannBasedMatcher matcher; + std::vector< DMatch > matches; + matcher.match( descriptors_1, descriptors_2, matches ); + + double max_dist = 0; double min_dist = 100; + + //-- Quick calculation of max and min distances between keypoints + for( int i = 0; i < descriptors_1.rows; i++ ) + { double dist = matches[i].distance; + if( dist < min_dist ) min_dist = dist; + if( dist > max_dist ) max_dist = dist; + } + + printf("-- Max dist : %f \n", max_dist ); + printf("-- Min dist : %f \n", min_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_1.rows; i++ ) + { if( matches[i].distance < 3*min_dist ) + { good_matches.push_back( matches[i]); } + } + + Mat img_matches; + drawMatches( img_1, keypoints_1, img_2, keypoints_2, + good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), + vector(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS ); + + + //-- Localize the object from img_1 in img_2 + std::vector obj; + std::vector scene; + + for( int i = 0; i < good_matches.size(); i++ ) + { + //-- Get the keypoints from the good matches + obj.push_back( keypoints_1[ good_matches[i].queryIdx ].pt ); + scene.push_back( keypoints_2[ good_matches[i].trainIdx ].pt ); + } + + Mat H = findHomography( obj, scene, CV_RANSAC ); + + //-- Get the corners from the image_1 ( the object to be "detected" ) + Point2f obj_corners[4] = { cvPoint(0,0), cvPoint( img_1.cols, 0 ), cvPoint( img_1.cols, img_1.rows ), cvPoint( 0, img_1.rows ) }; + Point scene_corners[4]; + + //-- Map these corners in the scene ( image_2) + for( int i = 0; i < 4; i++ ) + { + double x = obj_corners[i].x; + double y = obj_corners[i].y; + + double Z = 1./( H.at(2,0)*x + H.at(2,1)*y + H.at(2,2) ); + double X = ( H.at(0,0)*x + H.at(0,1)*y + H.at(0,2) )*Z; + double Y = ( H.at(1,0)*x + H.at(1,1)*y + H.at(1,2) )*Z; + scene_corners[i] = cvPoint( cvRound(X) + img_1.cols, cvRound(Y) ); + } + + //-- Draw lines between the corners (the mapped object in the scene - image_2 ) + line( img_matches, scene_corners[0], scene_corners[1], Scalar(0, 255, 0), 2 ); + line( img_matches, scene_corners[1], scene_corners[2], Scalar( 0, 255, 0), 2 ); + line( img_matches, scene_corners[2], scene_corners[3], Scalar( 0, 255, 0), 2 ); + line( img_matches, scene_corners[3], scene_corners[0], Scalar( 0, 255, 0), 2 ); + + //-- Show detected matches + imshow( "Good Matches & Object detection", img_matches ); + + waitKey(0); + + return 0; +} + +/** + * @function readme + */ +void readme() +{ std::cout << " Usage: ./SURF_descriptor " << std::endl; }