CascadeClassifier openCV - c++

Question

I wrote this program by C++ using OpenCV to detect pedestrians.xml file that I have. The program should read all of the input images and display blue rectangles on the output images where pedestrians are located. But the code is giving me errors. Is there anyone who can tell me why these errors come?
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/features2d/features2d.hpp>
#include<iostream>
#include <stdio.h>
#include <string>
#include <vector>
using namespace std;
using namespace cv;
void detectAndDisplay( Mat frame );
/** Global variables */
String pedestrians_name = "hogcascade_pedestrians.xml";
//CascadeClassifier pedestrians;
string window_name = "Capture - pedestrians detection";
RNG rng(12345);
/** #function main */
int main( int argc, const char** argv )
{
CvCapture* capture;
Mat frame;
//-- 1. Load the cascades
//if( !pedestrians.load( pedestrians_name ) ){ printf("--(!)Error loading\n"); return -1; };
Mat image = imread("ped1.jpg");
Mat image_keypoints;
cvtColor(image, image_keypoints, CV_BGR2GRAY);
return 0;
}
/** #function detectAndDisplay */
void detectAndDisplay( Mat frame )
{
std::vector<Rect> pedestrians;
Mat frame_gray;
cvtColor( frame, frame_gray, CV_BGR2GRAY );
equalizeHist( frame_gray, frame_gray );
//-- Detect faces
pedestrians.detectMultiScale( frame_gray, pedestrians, 1.1, 2, 0|CV_HAAR_SCALE_IMAGE, Size(30, 30) );
void CascadeClassifier::detectMultiScale(const Mat& image, vector<Rect>& objects, double scaleFactor=1.1, int minNeighbors=3, int flags=0, Size minSize=Size(), Size maxSize=Size());
for( int i = 0; i < pedestrians.size(); i++ )
{
Point center( pedestrians[i].x + pedestrians[i].width*0.5, pedestrians[i].y + pedestrians[i].height*0.5 );
ellipse( frame, center, Size( pedestrians[i].width*0.5, pedestrians[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 );
Mat faceROI = frame_gray( pedestrians[i] );
std::vector<Rect> eyes;
//-- In each face, detect eyes
/*eyes_cascade.detectMultiScale( faceROI, eyes, 1.1, 2, 0 |CV_HAAR_SCALE_IMAGE, Size(30, 30) );
for( size_t j = 0; j < eyes.size(); j++ )
{
Point center( faces[i].x + eyes[j].x + eyes[j].width*0.5, faces[i].y + eyes[j].y + eyes[j].height*0.5 );
int radius = cvRound( (eyes[j].width + eyes[j].height)*0.25 );
circle( frame, center, radius, Scalar( 255, 0, 0 ), 4, 8, 0 );
}*/
}
//-- Show what you got
imshow( window_name, frame );
}
these are the errors:
cascade.cpp: In function âvoid detectAndDisplay(cv::Mat)â:
cascade.cpp:46: error: âclass std::vector<cv::Rect_<int>, std::allocator<cv::Rect_<int> > >â has no member named âdetectMultiScaleâ
cascade.cpp:46: error: âCV_HAAR_SCALE_IMAGEâ was not declared in this scope
cascade.cpp:47: error: âCascadeClassifierâ has not been declared
cascade.cpp:47: error: invalid use of qualified-name â<declaration error>::detectMultiScaleâ

Answer 1

You need to add opencv_objdetect library. And include "opencv2/objdetect.hpp".

Answer 2

create a Cascade classifier object and load the xml file obj.load(xml file path)

Answer 3

First of all, in main() you never called detectAndDisplay() right? You need to call it if you want to execute it...
Second of all, you need to declare and load a cascade classifier in detectAndDisplay() before you use detectMultiScale.
CascadeClassifier pedestrians;
if( !pedestrians.load( pedestrians_name ) ){
printf("--(!)Error loading\n");
return;}
//.....
pedestrians.detectMultiScale( frame_gray, pedestrians, 1.1, 2, 0|CV_HAAR_SCALE_IMAGE, Size(30, 30) );