Problem with drawmatches()

asked 2016-08-30 12:42:46 -0500

art_bug gravatar image

updated 2016-09-09 17:43:03 -0500

Hi there,

I making logo detection program that uses the SIFT method to detect a logo on image. The latest version of code is

#include <core.hpp>
#include <highgui.hpp>
#include <imgproc.hpp>
#include <cv.hpp>
#include <imgcodecs.hpp>
#include <xfeatures2d.hpp>
#include <vector>
using namespace cv; using namespace cv::xfeatures2d; using std::vector;
vector<Mat> images, templates;
Mat temf = imread("C://DataSet_pic//reference//LEGO_logo.jpg"), teml = imread("C://DataSet_pic//reference//logo-blend-a-med.png");
Mat detectLogo(const Mat &source, const Mat &template_) { Ptr<Feature2D> sift = SIFT::create(); vector<KeyPoint> keypoints_s, keypoints_t; Mat descriptors_s, descriptors_t;
sift->detect(source, keypoints_s); sift->detect(template_, keypoints_t);
sift->compute(source, keypoints_s, descriptors_s); sift->compute(template_, keypoints_t, descriptors_t);
BFMatcher matcher; vector<vector<DMatch>> matches; matcher.knnMatch(descriptors_t, descriptors_s, matches, 2); vector<DMatch> good_matches; for(vector<DMatch> vdm : matches) for(DMatch dm : vdm) if(vdm.data()->distance < dm.distance / 2) good_matches.push_back(*(vdm.data()));
Mat img_matches;
if(good_matches.empty()) return img_matches;
drawMatches(template_, keypoints_t, source, keypoints_s, good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS); vector<Point2f> templt, scene;
for(unsigned int i = 0; i < good_matches.size(); i++) { templt.push_back( keypoints_t[ good_matches[i].queryIdx ].pt ); scene.push_back( keypoints_s[ good_matches[i].trainIdx ].pt ); }
if(templt.size() < 4 || scene.size() < 4) { img_matches.release(); return img_matches; }
Mat homogr = findHomography(templt, scene, CV_RANSAC); vector<Point2f> templ_corners(4);
templ_corners[0] = cvPoint(0,0); templ_corners[1] = cvPoint(template_.cols, 0); templ_corners[2] = cvPoint(template_.cols, template_.rows); templ_corners[3] = cvPoint(0, template_.rows);
vector<Point2f> scene_corners(4); perspectiveTransform(templ_corners, scene_corners, homogr);
Point p1 = scene_corners[0] + Point2f( template_.cols, 0), p2 = scene_corners[1] + Point2f( template_.cols, 0), p3 = scene_corners[2] + Point2f( template_.cols, 0), p4 = scene_corners[3] + Point2f( template_.cols, 0);
line( img_matches, p1, p2, Scalar(0, 255, 0), 4 ); line( img_matches, p2, p3, Scalar( 0, 255, 0), 4 ); line( img_matches, p3, p4, Scalar( 0, 255, 0), 4 ); line( img_matches, p4, p1, Scalar( 0, 255, 0), 4 );
return img_matches; }
void showFirstLogoMatch() { imshow("Logo detection", detectLogo(images[0], temf)); }
void showLastLogoMatch() { imshow("Logo detection", detectLogo(images[images.size()-1], teml)); }
void showLogoMatch(unsigned short int index) { Mat image = images[index]; Mat img = image.clone();
if(img.size().width == 1280 && img.size().height == 720) { Rect roi(Point(img.size().width / 2 - img.size().width / 4 + 50, img.size().height), Point(img.size().width / 2 + img.size().width / 4 + 50, 0)); Mat image_(img, roi); img = image_; } else if(img.size().width >= 500 && img.size().height >= 370) resize(img, img, Size(), 0.5, 0.5);
for(Mat mat : templates) { if( (mat.size().width >= 1280 || mat.size().width >= 324) && mat.size().height >= 324) resize(mat, mat, Size(), 0.5, 0.5);
Mat logo = detectLogo(img, mat);
if(logo.empty()) continue; else { imshow("Logo detection", logo); waitKey(0); } } }
int main() { vector<String> paths, paths_t; String folder = "C://DataSet_pic//", folder_t = "C://DataSet_pic//reference//";
glob(folder, paths); glob(folder_t, paths_t);
for(String str : paths) images.push_back(imread(str));
for(String str : paths_t) templates.push_back(imread(str));
unsigned int index = 0;
resize(temf, temf, Size(), 0.1667, 0.1667); resize ...




































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Comments

2

Please add the code here so that the question can still be useful after the link expires. "falling on image "13380-sony.jpg"." How do you expect someone to know what is happing?

FooBar gravatar imageFooBar ( 2016-08-30 13:11:06 -0500 )edit

My best gues --> your image was not read or processed correctly. Start by using absolute paths first. That being said, many of the active users stopped clicking links with code, so add it here or we will simply not even take a look at it!

StevenPuttemans gravatar imageStevenPuttemans ( 2016-09-05 04:37:23 -0500 )edit

Is there an error code? how far does the program get? you could make some NULL pointers, and set the variables for the images as NULL, then check those variables for NULL to know if they have been read properly.

j0h gravatar imagej0h ( 2016-09-05 14:17:45 -0500 )edit