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calibrate_camera_opencv
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Final changes, experimenting with parameters

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Razvan Mihalyi 12 years ago
parent 285c65b6fb
commit 879494c82e
1 changed files with 142 additions and 61 deletions
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203
calibrate.cc
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@ -19,11 +19,15 @@ enum { INTERACTIVE_MODE, PRESPECIFIED_MODE };
#define COUNT_SQUARES_X 4
#define COUNT_SQUARES_Y 6
int detect_pattern(Mat frame, vector< vector<Point3f> >& object_points, vector<vector<Point2f> >& image_points)
/**
* Method for detecting pattern in current frame.
* Returns world and image coordinates of detected corners via out parameters.
*/
bool detectPattern(Mat frame, vector< vector<Point3f> >& object_points, vector<vector<Point2f> >& image_points)
{
// interior number of corners
// number of squares in the pattern, a.k.a, interior number of corners
Size pattern_size(COUNT_SQUARES_X, COUNT_SQUARES_Y);
// will be filled by the detected corners
// storage for the detected corners in findChessboardConrners
vector<Point2f> corners;
bool pattern_found = findChessboardCorners(
@ -33,116 +37,193 @@ int detect_pattern(Mat frame, vector< vector<Point3f> >& object_points, vector<v
CALIB_CB_FAST_CHECK);
if (!pattern_found)
return -1;
return false;
// to tweak params: http://bit.ly/QyoU3k
// if corners are detected, they are further refined by calculating subpixel corners from the grayscale image
// this iterative process terminates after the given number of iterations and error epsilon
cornerSubPix(frame, corners, Size(11, 11), Size(-1, -1),
TermCriteria(CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 100,
0.1));
// draw the detected corners as sanity check
drawChessboardCorners(frame, pattern_size, Mat(corners),
pattern_found);
vector<Point3f> obj;
// show detected corners in a different window
imshow("Detected pattern", frame);
// build a grid of 3D points (z component is 0 because the pattern is in one plane) to fit the square pattern area (COUNT_SQUARES_X * COUNT_SQUARES_Y)
vector<Point3f> pattern_points;
for (int j = 0; j < COUNT_SQUARES_X * COUNT_SQUARES_Y; ++j)
obj.push_back(Point3f(j / COUNT_SQUARES_X, j % COUNT_SQUARES_X, 0.0f));
pattern_points.push_back(Point3f(j / COUNT_SQUARES_X, j % COUNT_SQUARES_X, 0.0f));
object_points.push_back(obj);
// populate image points with corners and object points with grid points
object_points.push_back(pattern_points);
image_points.push_back(corners);
return 0;
return true;
}
int run_interactive()
/**
* Main method for interactive behavior.
* Requires user to present calibration pattern in front of camera.
* By pressing SPACE the image is grabbed, pressing any other key loops through the camera stream, pressing ESC finishes calibration.
*/
int runInteractive()
{
cout << "Camera calibration using interactive behavior. Press SPACE to grab frame, ESC to quit.\n";
// show camera image in a separate window
namedWindow("Camera Image", CV_WINDOW_KEEPRATIO);
int count = 0;
Mat frame;
vector<vector<Point3f> > object_points;
vector<vector<Point2f> > image_points;
// current camera frame and first captured frame
Mat frame, first_frame;
// storage for object points (world coords) and image points (image coords) for use in calibrateCamera
vector< vector< Point3f > > object_points;
vector< vector< Point2f > > image_points;
// calibration parameters
Mat intrinsic = Mat(3, 3, CV_32FC1);
Mat distCoeffs;
vector<Mat> rvecs, tvecs;
// open the default camera
VideoCapture capture(-1);
VideoCapture capture(0);
// check if opening camera stream succeeded
if (!capture.isOpened()) {
if (!capture.isOpened())
{
cerr << "Camera could not be found. Exiting.\n";
return -1;
}
for (;;) {
cout << "Frame: " << count << endl;
// set frame width and height by hand, defaults to 160x120
capture.set (CV_CAP_PROP_FRAME_WIDTH, 640);
capture.set (CV_CAP_PROP_FRAME_HEIGHT, 480);
// flag for determining whether pattern was detected in at least one of the camera grabs
bool calibration_ready = false;
// flag for detecting first frame with pattern
bool first_flag = true;
for (int count_frames = 0; ; ++count_frames)
{
cout << "Frame: " << count_frames << endl;
capture >> frame; // get a new frame from camera
Mat gray_frame;
capture >> frame; // get a new frame from camera
cvtColor(frame, gray_frame, CV_BGR2GRAY);
imshow("Camera Image", frame);
cvtColor(frame, gray_frame, CV_BGR2GRAY); // convert current frame to grayscale
imshow("Camera Image", frame); // update camera image
int key_pressed = waitKey(0);
int key_pressed = waitKey(0); // get user key press
if (key_pressed == KEY_CLOSE_WINDOW || key_pressed == KEY_ESCAPE)
break;
if (key_pressed == KEY_SPACE) {
if (detect_pattern(gray_frame, object_points, image_points) == 0) {
cout << "Frame " << count << " grabbed." << endl;
} else {
cout << "pattern not found" << endl;
}
}
}
calibrateCamera(object_points, image_points, frame.size(), intrinsic,
distCoeffs, rvecs, tvecs);
if (key_pressed == KEY_SPACE)
{
if (detectPattern(gray_frame, object_points, image_points))
{
if (first_flag)
{
first_frame = frame; // save first frame for later use
first_flag = false;
}
cout << "Frame " << count_frames << " grabbed." << endl;
calibration_ready = true;
}
else cout << "Pattern not found" << endl;
}
else
continue;
for (;;) {
capture >> frame;
Mat imageUndistorted;
undistort(frame, imageUndistorted, intrinsic, distCoeffs);
imshow("win1", frame);
imshow("win2", imageUndistorted);
waitKey(1);
}
// if at least one video capture contains the pattern, perform calibration
if (calibration_ready)
{
// perform calibration, obtain instrinsic parameters and distortion coefficients
cout << "Calibrating..." << endl;
calibrateCamera(object_points, image_points, frame.size(), intrinsic,
distCoeffs, rvecs, tvecs);
Mat undistorted_frame;
// apply the calibration transformation to the first frame and store image on disk
undistort(first_frame, undistorted_frame, intrinsic, distCoeffs);
imwrite("first_frame.jpg", first_frame);
imwrite("undistorted_frame.jpg", undistorted_frame);
cout << "Applied undistortion to first frame (first_frame.jpg) and saved to undistorted_frame.jpg" << endl;
cout << "Intrinsic parameters:" << endl << intrinsic << endl;
cout << "Distortion coefficients:" << endl << distCoeffs << endl;
}
else
{
cerr << "No pattern found in any video capture. Exiting." << endl;
}
// release camera
capture.release();
}
int run_prespecified(int argc, char **argv)
int runPrespecified(int argc, char **argv)
{
int count = 0;
Mat frame;
// current camera frame and first captured frame
Mat frame, first_frame;
// storage for object points (world coords) and image points (image coords) for use in calibrateCamera
vector<vector<Point3f> > object_points;
vector<vector<Point2f> > image_points;
// calibration parameters
Mat intrinsic = Mat(3, 3, CV_32FC1);
Mat distCoeffs;
vector<Mat> rvecs, tvecs;
for (int i = 0; i < argc; i++) {
// flag for determining whether pattern was detected in at least one of the images
bool calibration_ready = false;
// flag for detecting first frame with pattern
bool first_flag = true;
// loop through the specified images
for (int i = 0; i < argc; i++)
{
Mat gray_frame;
cerr << endl << argv[i] << endl;
frame = imread(argv[i], CV_LOAD_IMAGE_COLOR);
cvtColor(frame, gray_frame, CV_BGR2GRAY);
imshow("Camera Image", frame);
if (detect_pattern(gray_frame, object_points, image_points) == 0) {
// apply pattern detection
if (detectPattern(gray_frame, object_points, image_points))
{
if (first_flag)
{
first_frame = frame;
first_flag = false;
}
cout << "Frame " << i << " grabbed." << endl;
} else {
cout << "Pattern not found in frame " << i << endl;
calibration_ready = true;
}
else
cout << "Pattern not found in frame " << i << endl;
}
cout << "Calibrating..." << endl;
calibrateCamera(object_points, image_points, frame.size(), intrinsic,
distCoeffs, rvecs, tvecs);
for (int i = 0; i < argc; i++) {
frame = imread(argv[i], CV_LOAD_IMAGE_COLOR);
Mat imageUndistorted;
undistort(frame, imageUndistorted, intrinsic, distCoeffs);
imshow("win1", frame);
imshow("win2", imageUndistorted);
waitKey(0);
// if at least one image contains the pattern, perform calibration
if (calibration_ready)
{
// perform calibration, obtain instrinsic parameters and distortion coefficients
cout << "Calibrating..." << endl;
calibrateCamera(object_points, image_points, frame.size(), intrinsic,
distCoeffs, rvecs, tvecs);
Mat undistorted_frame;
// apply the calibration transformation to the first frame and store image on disk
undistort(first_frame, undistorted_frame, intrinsic, distCoeffs);
imwrite("first_frame.jpg", first_frame);
imwrite("undistorted_frame.jpg", undistorted_frame);
cout << "Applied undistortion to first frame (first_frame.jpg) and saved to undistorted_frame.jpg" << endl;
cout << "Intrinsic parameters:" << endl << intrinsic << endl;
cout << "Distortion coefficients:" << endl << distCoeffs << endl;
}
else
{
cerr << "No pattern found in any of the images. Exiting." << endl;
}
return 0;
}
int main(int argc, char **argv)
@ -153,9 +234,9 @@ int main(int argc, char **argv)
/* no arguments means interactive mode
* one or more arguments are image filenames */
if (argc == 1) {
run_interactive();
runInteractive();
} else {
run_prespecified(argc-1, ++argv);
runPrespecified(argc-1, ++argv);
}
return 0;

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