How to detect triangle accurately in OpenCv using C++ - c++

Question

I am detecting red triangle objects in real time video using OpenCv c++. But my program is not working properly. Whether I cannot use findContours or approxPolyDP not much well. Here is my code
#include "opencv2/opencv.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
#include <raspicam/raspicam_cv.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
using namespace std;
int thresh = 100;
int number_pixels;
void drawAllTriangles(Mat&, const vector< vector<Point> >&);
int main(){
//Vectors
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
Mat canny_output,drawing;
//Initialise the image as a matrix container
Mat bgr;
raspicam::RaspiCam_Cv capture; // initialise the raspicam object
capture.open(); // activate the raspicam object
while (1)
{
capture.grab(); //grab the scene using raspicam
capture.retrieve(bgr); // retrieve the captured scene as an image and store it in matrix container
Mat gray,hsv; //Initialise the matrix container for gray color image
resize(bgr, bgr, Size(), .25, 0.25, CV_INTER_AREA);
//cvtColor(bgr, gray, COLOR_BGR2GRAY); //OpenCV code line for converting COLOR to GRAY scale image
//
cvtColor(bgr, hsv, COLOR_BGR2HSV);
//Gaussian Noice
Mat blure;
GaussianBlur(hsv,blure,Size(9,9),1.0);
//Gaussian Noice End
Mat mask1, mask2;
inRange(blure, Scalar(0,70,50), Scalar(10, 255, 255), mask1);
inRange(blure, Scalar(170, 70, 50), Scalar(180, 255, 255), mask2);
Mat mask3 = mask1 | mask2;
//Mat mask3 = mask1;
//
number_pixels = countNonZero(mask3);
Canny(mask3, canny_output, thresh, thresh*2, 3 );
findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
imshow("Original frame", bgr); //displaying original frame
imshow("Gray frame", mask3); //displaying original frame
drawAllTriangles(drawing,contours);
imshow("Triangles",drawing);
if (cvWaitKey(20) == 'q') // waitkey
break;
}
capture.release(); // release the raspicam frame grabbing
return 0;
}
void drawAllTriangles(Mat& img, const vector< vector<Point> >& contours){
vector<Point> approxTriangle;
for(size_t i = 0; i < contours.size(); i++){
approxPolyDP(contours[i], approxTriangle, arcLength(Mat(contours[i]), true)*0.05, true);
if(approxTriangle.size() == 3 and number_pixels>200){
drawContours(img, contours, i, Scalar(0, 255, 255), CV_FILLED); // fill GREEN
vector<Point>::iterator vertex;
for(vertex = approxTriangle.begin(); vertex != approxTriangle.end(); ++vertex){
circle(img, *vertex, 3, Scalar(0, 0, 255), 1);
}
printf("Triangle \n");
}
else {
printf("None \n");
}
}
}
My program should detect any red triangle shaped objects in video. Where I am going wrong. Thank you for answer
THese are the images, but it cannot detect triangles and confusing.