[OpenCV] Optical Flow / Lucas-Kanade Method

#include <cv.h> #include <cxcore.h> #include <highgui.h> #include <stdio.h> const int MAX_CORNERS = 500; int main(int argc, char** argv) { // Load images IplImage* imgA = cvLoadImage( "test_img_1.png", CV_LOAD_IMAGE_GRAYSCALE ); IplImage* imgB = cvLoadImage( "test_img_2.png", CV_LOAD_IMAGE_GRAYSCALE ); IplImage* imgC = cvLoadImage( "test_img_3.png", CV_LOAD_IMAGE_UNCHANGED ); CvSize img_sz = cvGetSize( imgA ); int win_size = 10; // Generate an image buffer used for cfGoodFeatureToTrack function IplImage* eig_image = cvCreateImage( img_sz, IPL_DEPTH_32F, 1 ); IplImage* tmp_image = cvCreateImage( img_sz, IPL_DEPTH_32F, 1 ); int corner_count = MAX_CORNERS; // Point variable for coordinates of detected features CvPoint2D32f* cornersA = new CvPoint2D32f[ MAX_CORNERS ]; // Detect features to track cvGoodFeaturesToTrack(imgA, eig_image, tmp_image, cornersA, &corner_count, 0.01, 5.0); // Variables for Lucas-Kanade algorihtm char features_found[ MAX_CORNERS ]; float feature_errors[ MAX_CORNERS ]; // CvSize pyr_sz = cvSize( imgA->width+8, imgB->height/3 ); // Generate Pyramid-buffer for Lucas-Kanade IplImage* pyrA = cvCreateImage( pyr_sz, IPL_DEPTH_32F, 1 ); IplImage* pyrB = cvCreateImage( pyr_sz, IPL_DEPTH_32F, 1 ); CvPoint2D32f* cornersB = new CvPoint2D32f[ MAX_CORNERS ]; // Execute Lucas-Kanade algorithm cvCalcOpticalFlowPyrLK( imgA, // Input image 1 imgB, // Input image 2 pyrA, // Buffer Pyramid pyrB, //... 2 cornersA, // CvPoint array of features cornersB, // Displacmenet of features stored corner_count, // Number of features above cvSize( win_size,win_size ), // Window size 5, // Number of iterations for the sake of detection of area more than winsize features_found, // Detection is successful : 1, fail: 0 feature_errors, // Every distance is sotred cvTermCriteria( CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 20, 0.3 ), // Sentinel 0 // flag = 0 ); // Generate image to be displayed for( int i = 0 ; i < corner_count ; i++ ) { // If the distance obtained is greater than 550, it is discarded if( features_found[i] == 0 || feature_errors[i] > 550 ) { printf("Error is %f\n", feature_errors[i]); continue; } printf("Got it\n"); // Draw deteced lines onto imgC CvPoint p0 = cvPoint( cvRound( cornersA[i].x ), cvRound( cornersA[i].y ) ); CvPoint p1 = cvPoint( cvRound( cornersB[i].x ), cvRound( cornersB[i].y ) ); cvLine( imgC, p0, p1, CV_RGB(255, 0, 0), 2 ); } // Display to the screen cvNamedWindow("ImageA", 0); cvNamedWindow("ImageB", 0); cvNamedWindow("LKpyr_OpticalFlow", 0); cvShowImage("ImageA", imgA); cvShowImage("ImageB", imgB); cvShowImage("LKpyr_OpticalFlow", imgC); cvWaitKey(0); // Return resources cvDestroyAllWindows(); cvReleaseImage( &imgA ); cvReleaseImage( &imgB ); cvReleaseImage( &imgC ); cvReleaseImage( &eig_image ); cvReleaseImage( &tmp_image ); cvReleaseImage( &pyrA ); cvReleaseImage( &pyrB ); delete [] cornersA; delete [] cornersB; return 0; }