Template Matching

The template matching code is as follows.

#include <iostream>#include <string>#include <vector>#include <stdio.h>#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>#include <opencv2/features2d/features2d.hpp>#include <opencv2/nonfree/features2d.hpp>#include <opencv2/legacy/legacy.hpp>#include "opencv2/video/tracking.hpp"using namespace cv;using namespace std;string intToString(int number) {std::stringstream ss;ss << number;return ss.str();}class Symbol {public:Mat img;string name;};void sortCorners(std::vector<cv::Point2f>& corners, cv::Point2f center) {std::vector<cv::Point2f> top, bot;for (unsigned int i = 0; i < corners.size(); i++) {if (corners[i].y < center.y)top.push_back(corners[i]);elsebot.push_back(corners[i]);}cv::Point2f tl = top[0].x > top[1].x ? top[1] : top[0];cv::Point2f tr = top[0].x > top[1].x ? top[0] : top[1];cv::Point2f bl = bot[0].x > bot[1].x ? bot[1] : bot[0];cv::Point2f br = bot[0].x > bot[1].x ? bot[0] : bot[1];corners.clear();corners.push_back(tl);corners.push_back(tr);corners.push_back(br);corners.push_back(bl);}int readRefImages(Symbol *symbols) {symbols[0].img = imread("arrowL.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[0].img.data)return -1;threshold(symbols[0].img, symbols[0].img, 100, 255, 0);symbols[0].name = "Left 90";symbols[1].img = imread("arrowR.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[1].img.data)return -1;threshold(symbols[1].img, symbols[1].img, 100, 255, 0);symbols[1].name = "Right 90";symbols[2].img = imread("arrowT.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[2].img.data)return -1;threshold(symbols[2].img, symbols[2].img, 100, 255, 0);symbols[2].name = "Turn Around";symbols[3].img = imread("arrowB.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[3].img.data)return -1;threshold(symbols[3].img, symbols[3].img, 100, 255, 0);symbols[3].name = "Ball";symbols[4].img = imread("arrowL45.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[4].img.data)return -1;threshold(symbols[4].img, symbols[4].img, 100, 255, 0);symbols[4].name = "Left 45";symbols[5].img = imread("arrowR45.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[5].img.data)return -1;threshold(symbols[5].img, symbols[5].img, 100, 255, 0);symbols[5].name = "Right 45";symbols[6].img = imread("arrowStop.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[6].img.data)return -1;threshold(symbols[6].img, symbols[6].img, 100, 255, 0);symbols[6].name = "Stop";symbols[7].img = imread("arrowGo.jpg", CV_LOAD_IMAGE_GRAYSCALE);if (!symbols[7].img.data)return -1;threshold(symbols[7].img, symbols[7].img, 100, 255, 0);symbols[7].name = "Go";return 0;}int lowThreshold;void CannyThreshold(int, void*) {}int main(int argc, char** argv) {// check http://docs.opencv.org/doc/tutorials/features2d/table_of_content_features2d/table_of_content_features2d.html// for OpenCV general detection/matching framework detailsVideoCapture cap;cap.open(0);namedWindow("A", CV_WINDOW_AUTOSIZE);namedWindow("B", CV_WINDOW_AUTOSIZE);namedWindow("C", CV_WINDOW_AUTOSIZE);Mat camera;Mat greyImg;Symbol symbols[10];if (readRefImages(symbols) == -1) {printf("Error reading reference symbols\n");return -1;}createTrackbar("Min Threshold:", "A", &lowThreshold, 100, CannyThreshold);double t = (double) getTickCount();// do something ...//t = ((double)getTickCount() - t)/getTickFrequency();//cout << "Times passed in seconds: " << t << endl;cap >> camera;Mat new_image;while (1) {t = (double) getTickCount() - t;cap >> camera;cvtColor(camera, greyImg, CV_RGB2GRAY);//threshold(greyImg, greyImg, 100, 255, 0);Mat canny_output;vector<vector<Point> > contours;vector<Vec4i> hierarchy;GaussianBlur(greyImg, greyImg, Size(9, 9), 2, 2);/// Detect edges using cannyCanny(greyImg, canny_output, lowThreshold, lowThreshold * 3, 3);//imshow("B",canny_output);/// Find contoursfindContours(canny_output, contours, hierarchy, CV_RETR_TREE,CV_CHAIN_APPROX_SIMPLE, Point(0, 0));vector<Point> approxRect;for (size_t i = 0; i < contours.size(); i++) {approxPolyDP(contours[i], approxRect,arcLength(Mat(contours[i]), true) * 0.05, true);if (approxRect.size() == 4) {float area = contourArea(contours[i]);if (area > 10000) {std::vector<cv::Point2f> corners;vector<Point>::iterator vertex;vertex = approxRect.begin();//vertex++;circle(camera, *vertex, 2, Scalar(0, 0, 255), -1, 8, 0);corners.push_back(*vertex);vertex++;circle(camera, *vertex, 2, Scalar(0, 0, 255), -1, 8, 0);corners.push_back(*vertex);vertex++;circle(camera, *vertex, 2, Scalar(0, 0, 255), -1, 8, 0);corners.push_back(*vertex);vertex++;circle(camera, *vertex, 2, Scalar(0, 0, 255), -1, 8, 0);corners.push_back(*vertex);Moments mu;mu = moments(contours[i], false);Point2f center(mu.m10 / mu.m00, mu.m01 / mu.m00);sortCorners(corners, center);// Define the destination imageMat correctedImg = ::Mat::zeros(195, 271, CV_8UC3);// Corners of the destination imagestd::vector<cv::Point2f> quad_pts;quad_pts.push_back(Point2f(0, 0));quad_pts.push_back(Point2f(correctedImg.cols, 0));quad_pts.push_back(Point2f(correctedImg.cols, correctedImg.rows));quad_pts.push_back(Point2f(0, correctedImg.rows));// Get transformation matrixMat transmtx = getPerspectiveTransform(corners, quad_pts);// Apply perspective transformationwarpPerspective(camera, correctedImg, transmtx,correctedImg.size());Mat correctedImgBin;cvtColor(correctedImg, correctedImgBin, CV_RGB2GRAY);//equalizeHist(correctedImgBin, correctedImgBin);correctedImgBin.copyTo(new_image);threshold(correctedImgBin, correctedImgBin, 140, 255, 0);imshow("B", correctedImgBin);double minVal,maxVal,medVal;minMaxLoc(new_image, &minVal, &maxVal);medVal=(maxVal-minVal)/2;threshold(new_image, new_image, medVal, 255, 0);imshow("C", new_image);Mat diffImg;int match, minDiff, diff;minDiff = 12000;match = -1;for (int i = 0; i < 8; i++) {//diffImg = symbols[i].img-correctedImgBin;bitwise_xor(new_image, symbols[i].img, diffImg,noArray());diff = countNonZero(diffImg);if (diff < minDiff) {minDiff = diff;match = i;}if (i == 0) {//imshow("B",diffImg);}}//imshow("B", correctedImg);if (match != -1) {putText(camera, symbols[match].name, Point(320, 30), 1,2, Scalar(0, 255, 0), 2);}//break;}}}imshow("A", camera);waitKey(20);}}