Open Source Computer Vision Library https://opencv.org/
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#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 images,\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);
}