opencv in c++ - findContours exception - c++

I am working with visual-studio and opencv lib and I have been trying to use findContours() but no matter what parameters I give the function it always triggers a break-point,
I have tried to make the image binary (b&w), reinstalling the library in different versions, messing with the linker preferences and anything I'v found on the web.
(this code is one of many i found on the web - they all crush one they get to findContours)
Does anyone know how to solve this problem ?
#include <iostream>
#include <vector>
#include "opencv2/opencv.hpp"
using namespace cv;
using std::vector;
int main()
{
vector<vector<cv::Point>> contours = vector<vector<cv::Point>>();
vector<Vec4i> hierarchy;
Mat frame, cont, threshold_;
VideoCapture capture = VideoCapture(0);
if (!capture.isOpened())
{
return -1;
}
while (true)
{
capture >> frame;
if (frame.empty()) break;
cont = frame.clone();
cvtColor(cont, cont, COLOR_BGR2GRAY);
cv::threshold(cont, cont, 128, 255, THRESH_BINARY);
threshold_ = cont.clone();
findContours(cont, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE);
for (unsigned int i = 0; i < contours.size(); i++)
{
drawContours(frame, contours, i, Scalar(0, 0, 255), 2);
}
imshow("Contour", threshold_);
imshow("Video", frame);
if (cv::waitKey(30) == 'q')
{
break;
}
}
return 0;
}

Related

[OpenCV][C++] Record only the detected motion

I'm working on a project to detect motion on a camera.
I need to start recording video when motion is detected for example:
Record while motion is being detected
Continue recording for 10 seconds after the motion detection is stopped
I have a working example that only detects the motion and draw rectangles on the moving parts.
I searched for examples on how to record when motion is detected but no good results.
Here is my working code:
#include <iostream>
#include <sstream>
#include <opencv4/opencv2/imgproc.hpp>
#include <opencv4/opencv2/videoio.hpp>
#include <opencv4/opencv2/highgui.hpp>
#include <opencv4/opencv2/video.hpp>
#include <unistd.h>
using namespace cv;
using namespace std;
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
int main(int argc, char* argv[])
{
//create Background Subtractor objects
Ptr<BackgroundSubtractor> pBackSub;
pBackSub = createBackgroundSubtractorMOG2();
VideoCapture capture(0);
if (!capture.isOpened()){
//error in opening the video input
cerr << "Unable to open: " << endl;
return 0;
}
Mat frame, fgMask;
sleep(3);
while (true) {
capture >> frame;
if (frame.empty())
break;
//update the background model
pBackSub->apply(frame, fgMask);
imshow("FG Mask", fgMask);
RNG rng(12345);
findContours(fgMask, contours, hierarchy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE,Point(0, 0));
vector<Rect>boundRect (contours.size());
vector<vector<Point> > contours_poly( contours.size() );
for (int i = 0; i < contours.size();i++) {
if( contourArea(contours[i])< 500)
{
continue;
}
putText(frame, "Motion Detected", Point(10,20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0,0,255),2);
approxPolyDP( contours[i], contours_poly[i], 3, true );
boundRect[i] = boundingRect( contours_poly[i] );
Scalar color = Scalar( rng.uniform(0, 256), rng.uniform(0,256), rng.uniform(0,256) );
rectangle( frame, boundRect[i].tl(), boundRect[i].br(), color, 2 );
}
imshow("Frame", frame);
int keyboard = waitKey(30);
if (keyboard == 'q' || keyboard == 27)
break;
}
return 0;
}
I tried adding this to the code:
int frameWidth = 320;
int frameHeight = 240;
cv::Size frameSize = cv::Size(frameWidth, frameHeight);
/* Output file */
int codec = cv::VideoWriter::fourcc('M', 'P', '4', 'V');
cv::VideoWriter outputVideo;
outputVideo.open("rr.mp4", codec, capture.get(cv::CAP_PROP_FPS), frameSize, true);
and after drawing the rectangle I write the frame to the video:
outputVideo.write(frame);
but after that, the video is empty and crashes.
I already took a look at Motion but I didn't find an example.
How can I achieve this?
Thanks,
Talel
I resolved the issue,
I was opening the output video with a specific dimensions (320,240) and I was saving the captured frame which is bigger.
So the solution is to resize the captured frame to fit into the output video.
Here is the final solution if anyone is interesting:
Turn the laptop camera into an IP camera with: cam2ip
Here is the source code:
#include <iostream>
#include <sstream>
#include <opencv4/opencv2/imgproc.hpp>
#include <opencv4/opencv2/videoio.hpp>
#include <opencv4/opencv2/highgui.hpp>
#include <opencv4/opencv2/video.hpp>
#include <unistd.h>
using namespace cv;
using namespace std;
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
int main(int argc, char* argv[])
{
//create Background Subtractor objects
Ptr<BackgroundSubtractor> pBackSub;
pBackSub = createBackgroundSubtractorMOG2();
const std::string videoStreamAddress = "http://192.168.20.100:56000/mjpeg";
cv::VideoCapture vcap;
if(!vcap.open(videoStreamAddress)) {
std::cout << "Error opening video stream or file" << std::endl;
return -1;
}
Mat frame, fgMask;
int frameWidth = 320;
int frameHeight = 240;
cv::Size frameSize = cv::Size(frameWidth, frameHeight);
/* Output file */
int codec = cv::VideoWriter::fourcc('M', 'P', '4', 'V');
cv::VideoWriter outputVideo;
outputVideo.open("rr.mp4", codec, vcap.get(cv::CAP_PROP_FPS), frameSize, true);
sleep(3);
while (true) {
vcap >> frame;
if (frame.empty())
break;
//update the background model
pBackSub->apply(frame, fgMask);
imshow("FG Mask", fgMask);
RNG rng(12345);
findContours(fgMask, contours, hierarchy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE,Point(0, 0));
vector<Rect>boundRect (contours.size());
vector<vector<Point> > contours_poly( contours.size() );
for (int i = 0; i < contours.size();i++) {
if( contourArea(contours[i])< 500)
{
continue;
}
putText(frame, "Motion Detected", Point(10,20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0,0,255),2);
approxPolyDP( contours[i], contours_poly[i], 3, true );
boundRect[i] = boundingRect( contours_poly[i] );
Scalar color = Scalar( rng.uniform(0, 256), rng.uniform(0,256), rng.uniform(0,256) );
rectangle( frame, boundRect[i].tl(), boundRect[i].br(), color, 2 );
resize(frame, frame, frameSize);
outputVideo.write(frame);
}
imshow("Frame", frame);
int keyboard = waitKey(30);
if (keyboard == 'q' || keyboard == 27)
break;
}
outputVideo.release();
return 0;
}
Further enhancement suggestions:
Make sure that the light is not part of the motion detection
Open an output video with the same capture's dimensions

How would I integrate the contourArea() function in my OpenCV program?

My code is for the purposes of detecting various shapes based off the number of vertices they have. I've finally accomplished that and it works perfectly for simple images like shown here: http://i.imgur.com/f9qvBwF.png However for this thresh image: http://i.imgur.com/jhl0NUQ.png it creates hundreds of shapes because of all the little pixels. Now I know enough of OpenCV to know there's eroding and dilating, but it seems like the best approach would be to exclude contours whose area is below a certain pixel count, however I don't know how to integrate the contourArea() function into my code such that it would work.
Here is my current code:
#include "opencv2/core/core.hpp"
#include "opencv2/flann/miniflann.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/photo/photo.hpp"
#include "opencv2/video/video.hpp"
#include "opencv2/features2d/features2d.hpp"
#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/calib3d/calib3d.hpp"
#include "opencv2/ml/ml.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/contrib/contrib.hpp"
#include "opencv2/core/core_c.h"
#include "opencv2/highgui/highgui_c.h"
#include "opencv2/imgproc/imgproc_c.h"
using namespace cv;
using namespace std;
Mat img;
Mat img_gray;
void contour_finder(int, void*);
int main(int argc, char *argv[])
{
img = imread("C:/Users/wyndr_000/Documents/VisualStudio2013/Projects/OpenCV_Template/OpenCV_Template/testpic.png", CV_LOAD_IMAGE_UNCHANGED);
cvtColor(img, img_gray, CV_RGB2GRAY);
contour_finder(0, 0);
waitKey();
}
void contour_finder(int, void*)
{
Mat img_thresh;
Mat drawn_contours;
threshold(img_gray, img_thresh, 183, 255, 2);
imshow("Thresh Image", img_thresh);
vector<vector<Point> > contours;
vector<Point> result;
findContours(img_thresh, contours, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
// Find a way to filter it out based on Area
for (size_t i = 0; i < contours.size(); i++){
approxPolyDP(Mat(contours[i]), result, arcLength(Mat(contours[i]), true)*0.02, true);
// if (contourArea(result) < 49)
//{
if (result.size() == 3)
{
cout << "TRIANGLE\n";
}
else if (result.size() == 4)
{
cout << "QUADRILATERAL\n";
}
else if (result.size() == 5)
{
cout << "PENTAGON\n";
}
else if (result.size() == 6)
{
cout << "HEXAGON\n";
}
else if (result.size() == 10)
{
cout << "STAR\n";
}
else if (result.size() == 12)
{
cout << "PLUS-SIGN\n";
}
// }
}
/* drawn_contours = Mat::zeros(img_thresh.size(), CV_8UC3);
for (int i = 0; i< contours.size(); i++)
{
Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
drawContours(drawn_contours, contours, i, color, 2, 8, hierarchy, 0, Point());
}
namedWindow("Contours", CV_WINDOW_AUTOSIZE);
imshow("Contours", drawn_contours); */
}
You'll notice where I declare what different amounts of vertices indicate, I have a commented contourArea function, because that's where I imagined it would go.

findContours returns assertion failed

Seems that the findContours function has been returning some assertion fails with Visual Studios C++ 2012. I've made sure that all my include directories were fine.
void track (Mat input_video, Mat &output_video)
{
Mat temp;
input_video.copyTo(temp);
vector<vector<cv::Point> > contours;
vector<Vec4i> hierarchy;
findContours(temp, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
//Only search through the most external layer.
for (int i=0; i>=0; i=hierarchy[i][0])
{
Moments moment = moments((Mat) contours[i]);
double area= moment.m00;
double xmc= moment.m10;
double ymc= moment.m01;
double x= xmc/area;
double y= ymc/area;
circle(output_video, Point(x,y), 3, Scalar(0,255,255));
}
}
EDIT:
The rest of my code if you may need it:
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace std;
using namespace cv;
//This function threshold the HSV image and create a binary image
Mat GetThresholdedImage(Mat imgHSV, int huemin, int satmin, int valmin, int huemax, int satmax, int valmax)
{
//Size s= imgHSV->size();
Mat imgThresh(imgHSV.size().height, imgHSV.size().width, CV_8U);
//returns matrix that contains all values within the given HSV range.
inRange(imgHSV, Scalar(huemin,satmin,valmin), Scalar(huemax,satmax,valmax), imgThresh);
return imgThresh;
}
Mat morph(Mat imgThresh)
{
Mat erode_element= getStructuringElement(MORPH_RECT, Size(3,3));
Mat dilate_element= getStructuringElement(MORPH_RECT, Size(8,8));
erode(imgThresh, imgThresh, erode_element);
erode(imgThresh, imgThresh, erode_element);
dilate(imgThresh, imgThresh, dilate_element);
return imgThresh;
}
void track (Mat input_video, Mat &output_video)
{
Mat temp;
input_video.copyTo(temp);
vector< vector<Point> > contours;
cerr<< contours.size();
vector<Vec4i> hierarchy;
findContours(temp, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
cerr<<contours.size();
//Only search through the most external layer.
for (int i=0; i>=0; i=hierarchy[i][0])
{
Moments moment = moments((Mat) contours[i]);
double area= moment.m00;
double xmc= moment.m10;
double ymc= moment.m01;
double x= xmc/area;
double y= ymc/area;
circle(output_video, Point(x,y), 3, Scalar(0,255,255));
}
}
int main()
{
VideoCapture capture(0);
if(!capture.isOpened()){
cerr<< "Capture failed";
return -1;
}
Mat frame;
namedWindow("Original");
namedWindow("Binary");
//Create slider for adjustments...
namedWindow("Adjustments");
int huemin= 0, satmin= 0, valmin= 0;
int huemax= 256, satmax= 256, valmax= 256;
createTrackbar("Min Hue", "Adjustments", &huemin, 256);
createTrackbar("Max Hue", "Adjustments", &huemax, 256);
createTrackbar("Min Saturation", "Adjustments", &satmin, 256);
createTrackbar("Max Saturation", "Adjustments", &satmax, 256);
createTrackbar("Min Value", "Adjustments", &valmin, 256);
createTrackbar("Max Value", "Adjustments", &valmax, 256);
//iterate through each frames of the video
while(true)
{
//Grabs each frame from video to be processed.
capture>> frame;
//Error checks and breaks if the grab failed.
if(!frame.data)
{
cerr<< "Failed to grab frame\n";
break;
}
//Apply a Gaussian Blur kernel.
//GaussianBlur(frame, frame, Size(3,3), 3, 3, 4);
Mat imgHSV(frame.size(), CV_8UC3);
cvtColor(frame, imgHSV, CV_BGR2HSV, 0); //Change the color format from BGR to HSV
Mat imgThresh = GetThresholdedImage(imgHSV, huemin, satmin, valmin, huemax, satmax, valmax);
//GaussianBlur(imgThresh, imgThresh, Size(5,5), 3, 3, 4); //smooth the binary image using Gaussian kernel
imgThresh= morph(imgThresh);
track(imgThresh, frame);
imshow("Binary", imgThresh);
imshow("Original", frame);
int key = waitKey(30);
//If 'ESC' is pressed, break the loop
if(key==27 ) break;
}
destroyAllWindows();
//cvReleaseCapture(&capture);
return 0;
}
Eugene, I encountered the same problem. try to add "cv::imshow("im", output_video);"
as mentioned in - OpenCV findContours causes Debug Assertion Failed at return

OpenCV Buffer Overflow

I've got myself in a pickle on this project I'm working on. My main objective is to stitch two webcam feeds together and do object detection on them - bounding boxes, etc...the standard stuff.
I can't rid myself of buffer overflows though - the somewhat simplified code below (for readability) compiles x64 and soon after I get a buffer overflow error and this in the console:
"OpenCV Error: Assertion Failed (contour.checkVector(2) >= 0 && (contour.depth() == CV_32F || CV_32S) in unknown function, file...."
If comment out all of the lines that have to do with contours (from findContours to drawBoundingBoxes in main) it compiles and runs fine until I hit the spacebar to stop the program, and then I get another buffer overflow error. I get the same errors when I compile x32 as well, for the record.
Any help? Relevant code/pseudo-code pasted below:
// **defines.h**
//Definitions for anything in all caps, like WIDTH, HEIGHT, ERODEIT, etc...
// **protos.h**
// All function prototypes, nothing else
// **detection.cpp**
/* This is the code that related to background subtraction operations*/
#include <opencv2/opencv.hpp>
#include <iostream>
#include "defines.h"
using namespace std;
using namespace cv;
void initBackgroundSubtractor(BackgroundSubtractorMOG2 &bSub)
{
bSub.set("detectShadows", 1);
}
Mat doBackgroundSubtract(BackgroundSubtractorMOG2 &bSub, Mat panorama)
{
Mat foreground;
bSub.operator()(panorama, foreground);
erode(foreground, foreground, Mat(), Point(-1, -1), ERODEIT, BORDER_DEFAULT);
dilate(foreground, foreground, Mat(), Point(-1, -1), DILATEIT, BORDER_DEFAULT);
return foreground;
}
// **contourOps.cpp**
/* Functions that operate on, filter, or relate to OpenCV contours vectors */
#include <opencv2/opencv.hpp>
#include <vector>
#include <fstream>
#include "defines.h"
using namespace std;
using namespace cv;
/* Returns the centroid of a contour */
Point getCentroid(vector<Point> contour)
{
Point centroid;
Moments m;
m = moments(contour, false);
centroid.x = int(m.m10/m.m00);
centroid.y = int(m.m01/m.m00);
return centroid;
}
/* Draws a rectangle around a contour */
void drawBoundingBoxes(vector<vector<Point>> contours, Mat &img)
{
vector<Rect> boundRect(contours.size());
for(unsigned int j = 0; j < contours.size(); j++)
{
boundRect[j] = boundingRect(contours[j]);
rectangle(img, boundRect[j], Scalar(153,0,76), 2, 8, 0);
}
}
/* Removes contours from a vector if they're smaller than the argument "area" */
void contourSizeTrim (vector<vector<Point>> &contours, int area)
{
vector<vector<Point>>::iterator i = contours.begin();
while(i != contours.end())
{
if(contourArea(*i, false) < area)
i = contours.erase(i);
else
i++;
}
}
/* Removes contours from a vector if they're X % smaller than largest contour in vector */
void contourRelSizeTrim(vector<vector<Point>> &contours, int percent)
{
double maxArea = 0.0;
for(unsigned int i=0; i<contours.size(); i++)
{
if (contourArea(contours[i], false) > maxArea)
maxArea = contourArea(contours[i], false);
}
vector<vector<Point>>::iterator j = contours.begin();
while(j != contours.end())
{
if (contourArea(*j, false) < (double)(percent/100.0)*maxArea)
j = contours.erase(j);
else
j++;
}
}
// **realtimestitch.cpp**
#include <opencv2/opencv.hpp>
#include <opencv2/stitching/stitcher.hpp>
#include <vector>
#include <iostream>
#include "defines.h"
using namespace std;
using namespace cv;
void initStitcher(VideoCapture &capture1, VideoCapture &capture2, Stitcher &stitch)
{
capture1.set(CV_CAP_PROP_FRAME_WIDTH, WIDTH);
capture1.set(CV_CAP_PROP_FRAME_HEIGHT, HEIGHT);
capture2.set(CV_CAP_PROP_FRAME_WIDTH, WIDTH);
capture2.set(CV_CAP_PROP_FRAME_HEIGHT, HEIGHT);
detail::OrbFeaturesFinder *featureFinder = new detail::OrbFeaturesFinder(Size(3,1), 1000, 1.5f, 4);
stitch.setFeaturesFinder (featureFinder);
}
void calcCamTransform(VideoCapture &capture1, VideoCapture &capture2, Stitcher &stitch)
{
int64 t;
Mat fr1, fr2, copy1, copy2;
vector<Mat> imgs;
capture1 >> fr1;
capture2 >> fr2;
fr1.copyTo(copy1);
fr2.copyTo(copy2);
imgs.push_back(copy1);
imgs.push_back(copy2);
stitch.estimateTransform(imgs);
}
Mat doStitch(VideoCapture &capture1, VideoCapture &capture2, Stitcher &stitch)
{
Mat fr1, fr2, copy1, copy2, panorama;
vector<Mat> imgs;
capture1 >> fr1;
capture2 >> fr2;
fr1.copyTo(copy1);
fr2.copyTo(copy2);
imgs.push_back(copy1);
imgs.push_back(copy2);
Stitcher::Status status = stitch.composePanorama(imgs, panorama);
if (status != Stitcher::OK)
cout << "Error Stitching: Code: " << int(status) << endl;
return panorama;
}
// **main.cpp**
#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
#include "defines.h"
#include "protos.h"
using namespace cv;
int main()
{
bool doTransform = true, doSizeFilter = true, doRelSizeFilter = true;
Mat pano, fGround;
vector<vector<Point>> contours;
VideoCapture cap1(0);
VideoCapture cap2(1);
Stitcher stitcher = Stitcher::createDefault();
BackgroundSubtractorMOG2 bGround;
initStitcher(cap1, cap2, stitcher);
initBackgroundSubtractor(bGround);
while (true)
{
if (doTransform)
{
calcCamTransform(cap1, cap2, stitcher);
doTransform = !doTransform;
}
pano = doStitch(cap1, cap2, stitcher);
fGround = doBackgroundSubtract(bGround, pano);
findContours(fGround, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE);
if (doSizeFilter)
contourSizeTrim(contours, AREATHRESH);
if (doRelSizeFilter)
contourRelSizeTrim(contours, RELSIZEPERCENT);
drawBoundingBoxes(contours, pano);
imshow("Stitched Image", pano);
if(waitKey(1) >= 0)
break;
}
return 0;
}
This is a problem related to OpenCV and VS2012 - on VS2010, there are no problems, and the code runs perfectly!
My opinion about this is that the contour you are trying to do something with an empty vector of contours. Have you verified that? Try a
if (contours.empty()) continue; // or here you can display the image to see if it is empty or not
I had the same problem because I was trying to give an epty vector to cv::IsContourConvex(...) function (see here).

Slow Video in Object Tracking Script using OpenCV

I wrote a short routine in openCV and C++ to track objects with a webcam. The webcam formulation was speedy with no lag, but before leaving work for the weekend, I recorded a typical sequence to use as a test template while I work until Monday. This and the corresponding change in code somehow make the video play back in really slow motion. Here is the code, opening "Test.avi", ~20 seconds long instead of running a constant stream off of the webcam:
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
#include <vector>
using namespace cv;
using namespace std;
Mat drawBoundingBoxes (Mat canvasImage, vector<vector<Point>> contours);
int main(int argc, char** argv[])
{
Mat frame;
Mat back;
Mat fGround;
BackgroundSubtractorMOG2 bGround;
bGround.nmixtures = 3;
//bGround.nShadowDetection = 0;
bGround.fTau = .5;
VideoCapture cap;
cap.open("Test.avi");
if (!cap.isOpened())
{
cout << "Can't open video" << endl;
return -1;
}
vector<vector<Point>> contours;
namedWindow("video", CV_WINDOW_AUTOSIZE);
while (true)
{
static int count = 1;
cap >> frame;
if (frame.empty())
break;
bGround.operator()(frame, fGround);
bGround.getBackgroundImage(back);
erode(fGround, fGround, Mat(), Point(-1,-1), 2, BORDER_DEFAULT);
dilate(fGround, fGround, Mat(), Point(-1,-1), 10, BORDER_DEFAULT);
if (count > 50)
{
findContours(fGround, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE);
drawContours(frame, contours, -1, Scalar(239,255,0), 2);
drawBoundingBoxes(frame, contours);
}
imshow("video", frame);
if(waitKey(30) >= 0)
break;
count++;
}
return 0;
}
Mat drawBoundingBoxes (Mat canvasImage, vector<vector<Point>> contours)
{
vector<Rect> boundRect(contours.size());
for (int i=0; i<contours.size(); i++)
{
boundRect[i] = boundingRect(contours[i]);
rectangle(canvasImage, boundRect[i], Scalar(153,0,76), 2, 8, 0);
}
return canvasImage;
}
Any ideas? Memory Leak somewhere? Thanks,
-Tony
I believe your recorded video has a higher framerate than that your PC can process real time. It's not a problem with a webcam as it just drops the frames. You could try to decrease the delay in the waitKey() procedure and see if that helps.