Error in BackgroundSubtraction Mog2
computer-vision, image-processing, opencv
Solution
Your displayed error says `(no parameter nmixture is found)`. The issue here is that you've typed `nmixture` instead of `nmixtures`.
Shadow detection cannot be set using the `.set()` function; this is a bug in opencv. If you'd like to set it, you should initialize it in your constructor. Here is how you should initialize your background model:
cv::BackgroundSubtractorMOG2 bg(history, distance_threshold, shadow_detection); // history is an int, distance_threshold is an int (usually set to 16), shadow_detection is a bool
Problem
I am using opencv 2.4.4 and when i run this algorithm on it , it give me the error on `nmixtures` and `bShadowDetection` ``` #include <iostream> #include <sys/stat.h> #include <stdio.h> #include <conio.h> #include <string.h> #include <stdlib.h> #include <opencv/cv.h> #include "opencv2/features2d/features2d.hpp" #include <opencv/highgui.h> #include "opencv2/opencv.hpp" #include "opencv2/core/core.hpp" #include "opencv2/nonfree/features2d.hpp" #include "opencv2/highgui/highgui.hpp" #include "opencv2/calib3d/calib3d.hpp" #include <vector> #pragma comment (lib , "opencv_core244d.lib") #pragma comment (lib ,"opencv_highgui244d.lib") #pragma comment(lib , "opencv_imgproc244d.lib") #pragma comment(lib ,"opencv_video244.lib") using namespace cv; int main(int argc, char *argv[]) { cv::Mat frame; cv::Mat back; cv::Mat fore; cv::VideoCapture cap("try2.avi"); cap >> frame; cv::initModule_video(); cv::BackgroundSubtractorMOG2 bg(100, 16, true); // history is an int, distance_threshold is an int (usually set to 16), shadow_detection is a bool bg.set("nmixtures", 3); bg(frame, fore, -1); //learning_rate = -1 here std::vector<std::vector<cv::Point> > contours; cv::namedWindow("Frame"); cv::namedWindow("Background"); for(;;) { cap >> frame; bg.operator ()(frame,fore); bg.getBackgroundImage(back); cv::erode(fore,fore,cv::Mat()); cv::dilate(fore,fore,cv::Mat()); cv::findContours(fore,contours,CV_RETR_EXTERNAL,CV_CHAIN_APPROX_NONE); cv::drawContours(frame,contours,-1,cv::Scalar(0,0,255),2); cv::imshow("Frame",frame); cv::imshow("Background",back); if(cv::waitKey(30) >= 0) break; } return 0; } ``` Error's ``` error C2248: 'cv::BackgroundSubtractorMOG2::nmixtures' : cannot access protected member declared in class 'cv::BackgroundSubtractorMOG2' error C2248: 'cv::BackgroundSubtractorMOG2::bShadowDetection' : cannot access protected member declared in class 'cv::BackgroundSubtractorMOG2' ``` When i use it like below , it didn't give syntax error , but give me error at runtime ``` bg.set("nmixtures", 3); bg.set("detectShadows", false); ``` Error ``` Unhandled exception at 0x7617812f in WK01.exe: Microsoft C++ exception: cv::Exception at memory location 0x001de2d0.. opencv error : Bad argument (no parameter nmixture is found) in unknown function ``` Thanks