opencv/samples/cpp/calibration_artificial.cpp

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>

#include <opencv2/calib3d/calib3d.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;
using namespace std;
void help()
{
	cout << "\nThis code generates an artificial camera and artificial chessboard views,\n"
         <<  "and then calibrates. It is basically test code for calibration that shows\n"
		 <<	"how to package calibration points and then calibrate the camera.\n"
		 <<	"Call:\n"
		 <<	"./calibration_artificial\n" << endl;
}
namespace cv
{

/* copy of class defines int tests/cv/chessboardgenerator.h */
class ChessBoardGenerator
{
public:
    double sensorWidth; 
    double sensorHeight;     
    size_t squareEdgePointsNum;
    double min_cos;
    mutable double cov;
    Size patternSize;
    int rendererResolutionMultiplier;

    ChessBoardGenerator(const Size& patternSize = Size(8, 6));
    Mat operator()(const Mat& bg, const Mat& camMat, const Mat& distCoeffs, vector<Point2f>& corners) const;    
    Size cornersSize() const;
private:
    void generateEdge(const Point3f& p1, const Point3f& p2, vector<Point3f>& out) const;
    Mat generageChessBoard(const Mat& bg, const Mat& camMat, const Mat& distCoeffs, 
        const Point3f& zero, const Point3f& pb1, const Point3f& pb2, 
        float sqWidth, float sqHeight, const vector<Point3f>& whole, vector<Point2f>& corners) const;
    void generateBasis(Point3f& pb1, Point3f& pb2) const;  
    Point3f generateChessBoardCenter(const Mat& camMat, const Size& imgSize) const;
    Mat rvec, tvec;
};
};



const Size imgSize(800, 600);
const Size brdSize(8, 7);
const size_t brds_num = 20;

template<class T> ostream& operator<<(ostream& out, const Mat_<T>& mat)
{    
    for(int j = 0; j < mat.rows; ++j)
        for(int i = 0; i < mat.cols; ++i)
            out << mat(j, i) << " ";        
    return out;
}



int main()
{          
	help();
    cout << "Initializing background...";    
    Mat background(imgSize, CV_8UC3);  
    randu(background, Scalar::all(32), Scalar::all(255));    
    GaussianBlur(background, background, Size(5, 5), 2);
    cout << "Done" << endl;

    cout << "Initializing chess board generator...";    
    ChessBoardGenerator cbg(brdSize);
    cbg.rendererResolutionMultiplier = 4;
    cout << "Done" << endl;

    /* camera params */
    Mat_<double> camMat(3, 3);
    camMat << 300., 0., background.cols/2., 0, 300., background.rows/2., 0., 0., 1.;
    
    Mat_<double> distCoeffs(1, 5);
    distCoeffs << 1.2, 0.2, 0., 0., 0.;
       
    cout << "Generating chessboards...";    
    vector<Mat> boards(brds_num);
    vector<Point2f> tmp;
    for(size_t i = 0; i < brds_num; ++i)
        cout << (boards[i] = cbg(background, camMat, distCoeffs, tmp), i) << " ";
    cout << "Done" << endl;    

    vector<Point3f> chessboard3D;
    for(int j = 0; j < cbg.cornersSize().height; ++j)
        for(int i = 0; i < cbg.cornersSize().width; ++i)
            chessboard3D.push_back(Point3i(i, j, 0));
    
    /* init points */
    vector< vector<Point3f> > objectPoints;    
    vector< vector<Point2f> > imagePoints;

    cout << endl << "Finding chessboards' corners...";
    for(size_t i = 0; i < brds_num; ++i)
    {
        cout << i;
        namedWindow("Current chessboard"); imshow("Current chessboard", boards[i]); waitKey(100);
        bool found = findChessboardCorners(boards[i], cbg.cornersSize(), tmp);
        if (found)
        {
            imagePoints.push_back(tmp);
            objectPoints.push_back(chessboard3D);             
            cout<< "-found ";                                   
        }
        else
            cout<< "-not-found ";        

        drawChessboardCorners(boards[i], cbg.cornersSize(), Mat(tmp), found);
        imshow("Current chessboard", boards[i]); waitKey(1000);
    }
    cout << "Done" << endl;
    cvDestroyAllWindows();
        
    Mat camMat_est;
    Mat distCoeffs_est;
    vector<Mat> rvecs, tvecs;
    
    cout << "Calibrating...";
    double rep_err = calibrateCamera(objectPoints, imagePoints, imgSize, camMat_est, distCoeffs_est, rvecs, tvecs);
    cout << "Done" << endl;

    cout << endl << "Average Reprojection error: " << rep_err/brds_num/cbg.cornersSize().area() << endl;
    cout << "==================================" << endl;
    cout << "Original camera matrix:\n" << camMat << endl;
    cout << "Original distCoeffs:\n" << distCoeffs << endl;
    cout << "==================================" << endl;
    cout << "Estiamted camera matrix:\n" << (Mat_<double>&)camMat_est << endl;
    cout << "Estiamted distCoeffs:\n" << (Mat_<double>&)distCoeffs_est << endl;
        
    return 0;
}


/////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////

// Copy of  tests/cv/src/chessboardgenerator code. Just do not want to add dependency.


ChessBoardGenerator::ChessBoardGenerator(const Size& _patternSize) : sensorWidth(32), sensorHeight(24),
    squareEdgePointsNum(200), min_cos(sqrt(2.f)*0.5f), cov(0.5), 
    patternSize(_patternSize), rendererResolutionMultiplier(4), tvec(Mat::zeros(1, 3, CV_32F))
{    
    Rodrigues(Mat::eye(3, 3, CV_32F), rvec);
}

void cv::ChessBoardGenerator::generateEdge(const Point3f& p1, const Point3f& p2, vector<Point3f>& out) const
{    
    Point3f step = (p2 - p1) * (1.f/squareEdgePointsNum);    
    for(size_t n = 0; n < squareEdgePointsNum; ++n)
        out.push_back( p1 + step * (float)n);
}    

Size cv::ChessBoardGenerator::cornersSize() const
{
    return Size(patternSize.width-1, patternSize.height-1);
}

struct Mult
{
    float m;
    Mult(int mult) : m((float)mult) {}
    Point2f operator()(const Point2f& p)const { return p * m; }    
};

void cv::ChessBoardGenerator::generateBasis(Point3f& pb1, Point3f& pb2) const
{
    RNG& rng = theRNG();

    Vec3f n;
    for(;;)
    {        
        n[0] = rng.uniform(-1.f, 1.f);
        n[1] = rng.uniform(-1.f, 1.f);
        n[2] = rng.uniform(-1.f, 1.f);        
        float len = (float)norm(n);    
        n[0]/=len;  
        n[1]/=len;  
        n[2]/=len;
        
        if (fabs(n[2]) > min_cos)
            break;
    }

    Vec3f n_temp = n; n_temp[0] += 100;
    Vec3f b1 = n.cross(n_temp); 
    Vec3f b2 = n.cross(b1);
    float len_b1 = (float)norm(b1);
    float len_b2 = (float)norm(b2);    

    pb1 = Point3f(b1[0]/len_b1, b1[1]/len_b1, b1[2]/len_b1);
    pb2 = Point3f(b2[0]/len_b1, b2[1]/len_b2, b2[2]/len_b2);
}

Mat cv::ChessBoardGenerator::generageChessBoard(const Mat& bg, const Mat& camMat, const Mat& distCoeffs, 
                                                const Point3f& zero, const Point3f& pb1, const Point3f& pb2, 
                                                float sqWidth, float sqHeight, const vector<Point3f>& whole,
                                                vector<Point2f>& corners) const
{
    vector< vector<Point> > squares_black;    
    for(int i = 0; i < patternSize.width; ++i)
        for(int j = 0; j < patternSize.height; ++j)
            if ( (i % 2 == 0 && j % 2 == 0) || (i % 2 != 0 && j % 2 != 0) ) 
            {            
                vector<Point3f> pts_square3d;
                vector<Point2f> pts_square2d;

                Point3f p1 = zero + (i + 0) * sqWidth * pb1 + (j + 0) * sqHeight * pb2;
                Point3f p2 = zero + (i + 1) * sqWidth * pb1 + (j + 0) * sqHeight * pb2;
                Point3f p3 = zero + (i + 1) * sqWidth * pb1 + (j + 1) * sqHeight * pb2;
                Point3f p4 = zero + (i + 0) * sqWidth * pb1 + (j + 1) * sqHeight * pb2;
                generateEdge(p1, p2, pts_square3d);
                generateEdge(p2, p3, pts_square3d);
                generateEdge(p3, p4, pts_square3d);
                generateEdge(p4, p1, pts_square3d);  
                
                projectPoints( Mat(pts_square3d), rvec, tvec, camMat, distCoeffs, pts_square2d);
                squares_black.resize(squares_black.size() + 1);  
                vector<Point2f> temp; 
                approxPolyDP(Mat(pts_square2d), temp, 1.0, true); 
                transform(temp.begin(), temp.end(), back_inserter(squares_black.back()), Mult(rendererResolutionMultiplier));             
            }  

    /* calculate corners */
    vector<Point3f> corners3d;    
    for(int j = 0; j < patternSize.height - 1; ++j)
        for(int i = 0; i < patternSize.width - 1; ++i)
            corners3d.push_back(zero + (i + 1) * sqWidth * pb1 + (j + 1) * sqHeight * pb2);
    corners.clear();
    projectPoints( Mat(corners3d), rvec, tvec, camMat, distCoeffs, corners);

    vector<Point3f> whole3d;
    vector<Point2f> whole2d;
    generateEdge(whole[0], whole[1], whole3d);
    generateEdge(whole[1], whole[2], whole3d);
    generateEdge(whole[2], whole[3], whole3d);
    generateEdge(whole[3], whole[0], whole3d);
    projectPoints( Mat(whole3d), rvec, tvec, camMat, distCoeffs, whole2d);
    vector<Point2f> temp_whole2d; 
    approxPolyDP(Mat(whole2d), temp_whole2d, 1.0, true); 

    vector< vector<Point > > whole_contour(1);
    transform(temp_whole2d.begin(), temp_whole2d.end(), 
        back_inserter(whole_contour.front()), Mult(rendererResolutionMultiplier));    

    Mat result;
    if (rendererResolutionMultiplier == 1)
    {        
        result = bg.clone();
        drawContours(result, whole_contour, -1, Scalar::all(255), CV_FILLED, CV_AA);       
        drawContours(result, squares_black, -1, Scalar::all(0), CV_FILLED, CV_AA);
    }
    else
    {
        Mat tmp;        
        resize(bg, tmp, bg.size() * rendererResolutionMultiplier);
        drawContours(tmp, whole_contour, -1, Scalar::all(255), CV_FILLED, CV_AA);       
        drawContours(tmp, squares_black, -1, Scalar::all(0), CV_FILLED, CV_AA);
        resize(tmp, result, bg.size(), 0, 0, INTER_AREA);
    }        
    return result;
}

Mat cv::ChessBoardGenerator::operator ()(const Mat& bg, const Mat& camMat, const Mat& distCoeffs, vector<Point2f>& corners) const
{      
    cov = min(cov, 0.8);
    double fovx, fovy, focalLen;
    Point2d principalPoint;
    double aspect;
    calibrationMatrixValues( camMat, bg.size(), sensorWidth, sensorHeight, 
        fovx, fovy, focalLen, principalPoint, aspect);

    RNG& rng = theRNG();

    float d1 = static_cast<float>(rng.uniform(0.1, 10.0)); 
    float ah = static_cast<float>(rng.uniform(-fovx/2 * cov, fovx/2 * cov) * CV_PI / 180);
    float av = static_cast<float>(rng.uniform(-fovy/2 * cov, fovy/2 * cov) * CV_PI / 180);        
    
    Point3f p;
    p.z = cos(ah) * d1;
    p.x = sin(ah) * d1;
    p.y = p.z * tan(av);  

    Point3f pb1, pb2;    
    generateBasis(pb1, pb2);
            
    float cbHalfWidth = static_cast<float>(norm(p) * sin( min(fovx, fovy) * 0.5 * CV_PI / 180));
    float cbHalfHeight = cbHalfWidth * patternSize.height / patternSize.width;
    
    vector<Point3f> pts3d(4);
    vector<Point2f> pts2d(4);
    for(;;)
    {        
        pts3d[0] = p + pb1 * cbHalfWidth + cbHalfHeight * pb2;
        pts3d[1] = p + pb1 * cbHalfWidth - cbHalfHeight * pb2;
        pts3d[2] = p - pb1 * cbHalfWidth - cbHalfHeight * pb2;
        pts3d[3] = p - pb1 * cbHalfWidth + cbHalfHeight * pb2;
        
        /* can remake with better perf */
        projectPoints( Mat(pts3d), rvec, tvec, camMat, distCoeffs, pts2d);

        bool inrect1 = pts2d[0].x < bg.cols && pts2d[0].y < bg.rows && pts2d[0].x > 0 && pts2d[0].y > 0;
        bool inrect2 = pts2d[1].x < bg.cols && pts2d[1].y < bg.rows && pts2d[1].x > 0 && pts2d[1].y > 0;
        bool inrect3 = pts2d[2].x < bg.cols && pts2d[2].y < bg.rows && pts2d[2].x > 0 && pts2d[2].y > 0;
        bool inrect4 = pts2d[3].x < bg.cols && pts2d[3].y < bg.rows && pts2d[3].x > 0 && pts2d[3].y > 0;
        
        if ( inrect1 && inrect2 && inrect3 && inrect4)
            break;

        cbHalfWidth*=0.8f;
        cbHalfHeight = cbHalfWidth * patternSize.height / patternSize.width;        
    }

    cbHalfWidth  *= static_cast<float>(patternSize.width)/(patternSize.width + 1);
    cbHalfHeight *= static_cast<float>(patternSize.height)/(patternSize.height + 1);

    Point3f zero = p - pb1 * cbHalfWidth - cbHalfHeight * pb2;
    float sqWidth  = 2 * cbHalfWidth/patternSize.width;
    float sqHeight = 2 * cbHalfHeight/patternSize.height;
        
    return generageChessBoard(bg, camMat, distCoeffs, zero, pb1, pb2, sqWidth, sqHeight,  pts3d, corners);      
}