Multiple template matching only detects one match

Question

I\'m trying to match this image

in this image

However, I can\'t find more than one boss enemy. What do I need to do to find the others?

Answer 1

I didn't debug your code, but since it doesn't work (probably floodfill is messing up your result matrix), this is a simple working sample.

I iterate over the maximum points in the result matrix finding the blobs where values are over a threshold, and finding the highest value within each blob (used as a mask to retrieve actual values in the result matrix).

#include <opencv2\opencv.hpp>
#include <vector>
using namespace std;
using namespace cv;

int main()
{
    Mat3b img = imread("path_to_image");
    Mat3b templ = imread("path_to_template");

    Mat1b img_gray;
    Mat1b templ_gray;
    cvtColor(img, img_gray, COLOR_BGR2GRAY);
    cvtColor(templ, templ_gray, COLOR_BGR2GRAY);

    Mat1f result;
    matchTemplate(img, templ, result, TM_CCOEFF_NORMED);

    double thresh = 0.7;
    threshold(result, result, thresh, 1., THRESH_BINARY);

    Mat1b resb;
    result.convertTo(resb, CV_8U, 255);

    vector<vector<Point>> contours;
    findContours(resb, contours, RETR_LIST, CHAIN_APPROX_SIMPLE);

    for (int i=0; i<contours.size(); ++i)
    {
        Mat1b mask(result.rows, result.cols, uchar(0));
        drawContours(mask, contours, i, Scalar(255), CV_FILLED);

        Point max_point;
        double max_val;
        minMaxLoc(result, NULL, &max_val, NULL, &max_point, mask);

        rectangle(img, Rect(max_point.x, max_point.y, templ.cols, templ.rows), Scalar(0,255,0), 2);
    }
    return 0;
}

Result: