camera calibration opencv

Question

Hi i am doing a project to do an image 3d reconstruction. I am the phase of calibrating the camera, which is taking a long time to do. But when i compile the code and display the checkerboard in front of the camera it goes straight to exception error unhandled.

When picture not in frame, no error as soon as it gets in the frame, unhandled error occurs i don't know why.

I have asked a lot of people, no body can seem to help.

here is my code

#include <cv.h>
#include <highgui.h>
#include <vector>
#include <stdlib.h>
#include <stdio.h>

using namespace cv;
using namespace std;

int main()
{
    int numBoards = 0;
    int numCornersHor;
    int numCornersVer;

    printf("Enter number of corners along width: ");
    scanf("%d", &numCornersHor);

    printf("Enter number of corners along height: ");
    scanf("%d", &numCornersVer);

    printf("Enter number of boards: ");
    scanf("%d", &numBoards);

    int numSquares = numCornersHor * numCornersVer;
    Size board_sz = Size(numCornersHor, numCornersVer);
    VideoCapture capture = VideoCapture(0);

    vector<vector<Point3d>> object_points;
    vector<vector<Point2d>> image_points;

    vector<Point2d> corners;
    int successes=0;

    Mat image;
    Mat gray_image;
    capture >> image;

    vector<Point3d> obj;
    for(int j=0;j<numSquares;j++)
        obj.push_back(Point3d(j/numCornersHor, j%numCornersHor, 0.0f));

    while(successes<numBoards)
    {
        cvtColor(image, gray_image, CV_BGR2GRAY);

        bool found = findChessboardCorners(image, board_sz, corners, CV_CALIB_CB_ADAPTIVE_THRESH | CV_CALIB_CB_FILTER_QUADS);

        if(found)
        {
            cornerSubPix(gray_image, corners, Size(11, 11), Size(-1, -1), TermCriteria(CV_TERMCRIT_EPS | CV_TERMCRIT_ITER, 30, 0.1));
            drawChessboardCorners(gray_image, board_sz, corners, found);
        }

        imshow("win1", image);
        imshow("win2", gray_image);

        capture >> image;

        int key = waitKey(1);

        if(key==27)
            return 0;

        if(key==' ' && found!=0)
        {
            image_points.push_back(corners);
            object_points.push_back(obj);
            printf("Snap stored!\n");

            successes++;

            if(successes>=numBoards)
                break;
        }
    }

    Mat intrinsic = Mat(3, 3, CV_32FC1);
    Mat distCoeffs;
    vector<Mat> rvecs;
    vector<Mat> tvecs;

    intrinsic.ptr<float>(0)[0] = 1;
    intrinsic.ptr<float>(1)[1] = 1;

    calibrateCamera(object_points, image_points, image.size(), intrinsic, distCoeffs, rvecs, tvecs);

    Mat imageUndistorted;
    while(1)
    {
        capture >> image;
        undistort(image, imageUndistorted, intrinsic, distCoeffs);

        imshow("win1", image);
        imshow("win2", imageUndistorted);

        waitKey(1);
    }

    capture.release();

    return 0;
}

the error i get on the console is

OpenCV ERROR: Assertion failed (ncorners >=0 && corners.depth() == CV_32F) in unknown function file , file .....\src\opencv\modules\imgproc\src\cornersubpix.cpp, line 257.

and the error dialog says

Unhandled exception at 0x769afc16 in basiccalibration.exe: Microsoft C++ exception: cv::Exception at memory location 0x0021f51c..

Help would be appreciated. Thanks

The opencv package has a sample code within it to calibrate cameras, are you using that? — Rui Marques
no, i want to write my own code. i tried that but it had too many errors such as undefined functions. — Seif Sharif
I am trying to run the same code than you. Actually my code was a bit different, but I modified it to get some thing close to you and try solve my problem here. Some questions: In your final version, are you really using numCornersHor twice? Why are you not using numCornersVer as second parameter? And did you define both as float when you declared them? Thanks for your help! — user2414816

morynicz morynicz · Accepted Answer · 2013-02-13T09:26:56

Use Point2f and Point3f instead of Point2d and Point3d. Read the assertion text please. It demands a CV_32F depth structure.

camera calibration opencv

1 Answers