#include "cv.h"
#include "highgui.h"
#include <stdio.h>
#include <string.h>
#include <time.h>
// example command line (for copy-n-paste):
// calibration -w 6 -h 8 -s 2 -n 10 -o camera.yml -op -oe [<list_of_views.txt>]
/* The list of views may look as following (discard the starting and ending ------ separators):
-------------------
view000.png
view001.png
#view002.png
view003.png
view010.png
one_extra_view.jpg
-------------------
that is, the file will contain 6 lines, view002.png will not be used for calibration,
other ones will be (those, in which the chessboard pattern will be found)
*/
enum { DETECTION = 0, CAPTURING = 1, CALIBRATED = 2 };
double compute_reprojection_error( const CvMat* object_points,
const CvMat* rot_vects, const CvMat* trans_vects,
const CvMat* camera_matrix, const CvMat* dist_coeffs,
const CvMat* image_points, const CvMat* point_counts,
CvMat* per_view_errors )
{
CvMat* image_points2 = cvCreateMat( image_points->rows,
image_points->cols, image_points->type );
int i, image_count = rot_vects->rows, points_so_far = 0;
double total_err = 0, err;
for( i = 0; i < image_count; i++ )
{
CvMat object_points_i, image_points_i, image_points2_i;
int point_count = point_counts->data.i[i];
CvMat rot_vect, trans_vect;
cvGetCols( object_points, &object_points_i,
points_so_far, points_so_far + point_count );
cvGetCols( image_points, &image_points_i,
points_so_far, points_so_far + point_count );
cvGetCols( image_points2, &image_points2_i,
points_so_far, points_so_far + point_count );
points_so_far += point_count;
cvGetRow( rot_vects, &rot_vect, i );
cvGetRow( trans_vects, &trans_vect, i );
cvProjectPoints2( &object_points_i, &rot_vect, &trans_vect,
camera_matrix, dist_coeffs, &image_points2_i,
0, 0, 0, 0, 0 );
err = cvNorm( &image_points_i, &image_points2_i, CV_L1 );
if( per_view_errors )
per_view_errors->data.db[i] = err/point_count;
total_err += err;
}
cvReleaseMat( &image_points2 );
return total_err/points_so_far;
}
int run_calibration( CvSeq* image_points_seq, CvSize img_size, CvSize board_size,
float square_size, float aspect_ratio, int flags,
CvMat* camera_matrix, CvMat* dist_coeffs, CvMat** extr_params,
CvMat** reproj_errs, double* avg_reproj_err )
{
int code;
int image_count = image_points_seq->total;
int point_count = board_size.width*board_size.height;
CvMat* image_points = cvCreateMat( 1, image_count*point_count, CV_32FC2 );
CvMat* object_points = cvCreateMat( 1, image_count*point_count, CV_32FC3 );
CvMat* point_counts = cvCreateMat( 1, image_count, CV_32SC1 );
CvMat rot_vects, trans_vects;
int i, j, k;
CvSeqReader reader;
cvStartReadSeq( image_points_seq, &reader );
// initialize arrays of points
for( i = 0; i < image_count; i++ )
{
CvPoint2D32f* src_img_pt = (CvPoint2D32f*)reader.ptr;
CvPoint2D32f* dst_img_pt = ((CvPoint2D32f*)image_points->data.fl) + i*point_count;
CvPoint3D32f* obj_pt = ((CvPoint3D32f*)object_points->data.fl) + i*point_count;
for( j = 0; j < board_size.height; j++ )
for( k = 0; k < board_size.width; k++ )
{
*obj_pt++ = cvPoint3D32f(j*square_size, k*square_size, 0);
*dst_img_pt++ = *src_img_pt++;
}
CV_NEXT_SEQ_ELEM( image_points_seq->elem_size, reader );
}
cvSet( point_counts, cvScalar(point_count) );
*extr_params = cvCreateMat( image_count, 6, CV_32FC1 );
cvGetCols( *extr_params, &rot_vects, 0, 3 );
cvGetCols( *extr_params, &trans_vects, 3, 6 );
cvZero( camera_matrix );
cvZero( dist_coeffs );
if( flags & CV_CALIB_FIX_ASPECT_RATIO )
{
camera_matrix->data.db[0] = aspect_ratio;
camera_matrix->data.db[4] = 1.;
}
cvCalibrateCamera2( object_points, image_points, point_counts,
img_size, camera_matrix, dist_coeffs,
&rot_vects, &trans_vects, flags );
code = cvCheckArr( camera_matrix, CV_CHECK_QUIET ) &&
cvCheckArr( dist_coeffs, CV_CHECK_QUIET ) &&
cvCheckArr( *extr_params, CV_CHECK_QUIET );
*reproj_errs = cvCreateMat( 1, image_count, CV_64FC1 );
*avg_reproj_err =
compute_reprojection_error( object_points, &rot_vects, &trans_vects,
camera_matrix, dist_coeffs, image_points, point_counts, *reproj_errs );
cvReleaseMat( &object_points );
cvReleaseMat( &image_points );
cvReleaseMat( &point_counts );
return code;
}
void save_camera_params( const char* out_filename, int image_count, CvSize img_size,
CvSize board_size, float square_size,
float aspect_ratio, int flags,
const CvMat* camera_matrix, CvMat* dist_coeffs,
const CvMat* extr_params, const CvSeq* image_points_seq,
const CvMat* reproj_errs, double avg_reproj_err )
{
CvFileStorage* fs = cvOpenFileStorage( out_filename, 0, CV_STORAGE_WRITE );
time_t t;
time( &t );
struct tm *t2 = localtime( &t );
char buf[1024];
strftime( buf, sizeof(buf)-1, "%c", t2 );
cvWriteString( fs, "calibration_time", buf );
cvWriteInt( fs, "image_count", image_count );
cvWriteInt( fs, "image_width", img_size.width );
cvWriteInt( fs, "image_height", img_size.height );
cvWriteInt( fs, "board_width", board_size.width );
cvWriteInt( fs, "board_height", board_size.height );
cvWriteReal( fs, "square_size", square_size );
if( flags & CV_CALIB_FIX_ASPECT_RATIO )
cvWriteReal( fs, "aspect_ratio", aspect_ratio );
if( flags != 0 )
{
sprintf( buf, "flags: %s%s%s%s",
flags & CV_CALIB_USE_INTRINSIC_GUESS ? "+use_intrinsic_guess" : "",
flags & CV_CALIB_FIX_ASPECT_RATIO ? "+fix_aspect_ratio" : "",
flags & CV_CALIB_FIX_PRINCIPAL_POINT ? "+fix_principal_point" : "",
flags & CV_CALIB_ZERO_TANGENT_DIST ? "+zero_tangent_dist" : "" );
cvWriteComment( fs, buf, 0 );
}
cvWriteInt( fs, "flags", flags );
cvWrite( fs, "camera_matrix", camera_matrix );
cvWrite( fs, "distortion_coefficients", dist_coeffs );
cvWriteReal( fs, "avg_reprojection_error", avg_reproj_err );
if( reproj_errs )
cvWrite( fs, "per_view_reprojection_errors", reproj_errs );
if( extr_params )
{
cvWriteComment( fs, "a set of 6-tuples (rotation vector + translation vector) for each view", 0 );
cvWrite( fs, "extrinsic_parameters", extr_params );
}
if( image_points_seq )
{
cvWriteComment( fs, "the array of board corners projections used for calibration", 0 );
assert( image_points_seq->total == image_count );
CvMat* image_points = cvCreateMat( 1, image_count*board_size.width*board_size.height, CV_32FC2 );
cvCvtSeqToArray( image_points_seq, image_points->data.fl );
cvWrite( fs, "image_points", image_points );
cvReleaseMat( &image_points );
}
cvReleaseFileStorage( &fs );
}
int main( int argc, char** argv )
{
CvSize board_size = {0,0};
float square_size = 1.f, aspect_ratio = 1.f;
const char* out_filename = "out_camera_data.yml";
const char* input_filename = 0;
int i, image_count = 10;
int write_extrinsics = 0, write_points = 0;
int flags = 0;
CvCapture* capture = 0;
FILE* f = 0;
char imagename[1024];
CvMemStorage* storage;
CvSeq* image_points_seq = 0;
int elem_size, flip_vertical = 0;
int delay = 1000;
clock_t prev_timestamp = 0;
CvPoint2D32f* image_points_buf = 0;
CvFont font = cvFont( 1, 1 );
double _camera[9], _dist_coeffs[4];
CvMat camera = cvMat( 3, 3, CV_64F, _camera );
CvMat dist_coeffs = cvMat( 1, 4, CV_64F, _dist_coeffs );
CvMat *extr_params = 0, *reproj_errs = 0;
double avg_reproj_err = 0;
int mode = DETECTION;
int undistort_image = 0;
CvSize img_size = {0,0};
const char* live_capture_help =
"When the live video from camera is used as input, the following hot-keys may be used:\n"
" <ESC>, 'q' - quit the program\n"
" 'g' - start capturing images\n"
" 'u' - switch undistortion on/off\n";
if( argc < 2 )
{
printf( "This is a camera calibration sample.\n"
"Usage: calibration\n"
" -w <board_width> # the number of inner corners per one of board dimension\n"
" -h <board_height> # the number of inner corners per another board dimension\n"
" [-n <number_of_frames>] # the number of frames to use for calibration\n"
" # (if not specified, it will be set to the number\n"
" # of board views actually available)\n"
" [-d <delay>] # a minimum delay in ms between subsequent attempts to capture a next view\n"
" # (used only for video capturing)\n"
" [-s <square_size>] # square size in some user-defined units (1 by default)\n"
" [-o <out_camera_params>] # the output filename for intrinsic [and extrinsic] parameters\n"
" [-op] # write detected feature points\n"
" [-oe] # write extrinsic parameters\n"
" [-zt] # assume zero tangential distortion\n"
" [-a <aspect_ratio>] # fix aspect ratio (fx/fy)\n"
" [-p] # fix the principal point at the center\n"
" [-v] # flip the captured images around the horizontal axis\n"
" [input_data] # input data, one of the following:\n"
" # - text file with a list of the images of the board\n"
" # - name of video file with a video of the board\n"
" # if input_data not specified, a live view from the camera is used\n"
"\n" );
printf( "%s", live_capture_help );
return 0;
}
for( i = 1; i < argc; i++ )
{
const char* s = argv[i];
if( strcmp( s, "-w" ) == 0 )
{
if( sscanf( argv[++i], "%u", &board_size.width ) != 1 || board_size.width <= 0 )
return fprintf( stderr, "Invalid board width\n" ), -1;
}
else if( strcmp( s, "-h" ) == 0 )
{
if( sscanf( argv[++i], "%u", &board_size.height ) != 1 || board_size.height <= 0 )
return fprintf( stderr, "Invalid board height\n" ), -1;
}
else if( strcmp( s, "-s" ) == 0 )
{
if( sscanf( argv[++i], "%f", &square_size ) != 1 || square_size <= 0 )
return fprintf( stderr, "Invalid board square width\n" ), -1;
}
else if( strcmp( s, "-n" ) == 0 )
{
if( sscanf( argv[++i], "%u", &image_count ) != 1 || image_count <= 3 )
return printf("Invalid number of images\n" ), -1;
}
else if( strcmp( s, "-a" ) == 0 )
{
if( sscanf( argv[++i], "%f", &aspect_ratio ) != 1 || aspect_ratio <= 0 )
return printf("Invalid aspect ratio\n" ), -1;
}
else if( strcmp( s, "-d" ) == 0 )
{
if( sscanf( argv[++i], "%u", &delay ) != 1 || delay <= 0 )
return printf("Invalid delay\n" ), -1;
}
else if( strcmp( s, "-op" ) == 0 )
{
write_points = 1;
}
else if( strcmp( s, "-oe" ) == 0 )
{
write_extrinsics = 1;
}
else if( strcmp( s, "-zt" ) == 0 )
{
flags |= CV_CALIB_ZERO_TANGENT_DIST;
}
else if( strcmp( s, "-p" ) == 0 )
{
flags |= CV_CALIB_FIX_PRINCIPAL_POINT;
}
else if( strcmp( s, "-v" ) == 0 )
{
flip_vertical = 1;
}
else if( strcmp( s, "-o" ) == 0 )
{
out_filename = argv[++i];
}
else if( s[0] != '-' )
input_filename = s;
else
return fprintf( stderr, "Unknown option %s", s ), -1;
}
if( input_filename )
{
capture = cvCreateFileCapture( input_filename );
if( !capture )
{
f = fopen( input_filename, "rt" );
if( !f )
return fprintf( stderr, "The input file could not be opened\n" ), -1;
image_count = -1;
}
mode = CAPTURING;
}
else
capture = cvCreateCameraCapture(0);
if( !capture && !f )
return fprintf( stderr, "Could not initialize video capture\n" ), -2;
if( capture )
printf( "%s", live_capture_help );
elem_size = board_size.width*board_size.height*sizeof(image_points_buf[0]);
storage = cvCreateMemStorage( MAX( elem_size*4, 1 << 16 ));
image_points_buf = (CvPoint2D32f*)cvAlloc( elem_size );
image_points_seq = cvCreateSeq( 0, sizeof(CvSeq), elem_size, storage );
cvNamedWindow( "Image View", 1 );
for(;;)
{
IplImage *view = 0, *view_gray = 0;
int count = 0, found, blink = 0;
CvPoint text_origin;
CvSize text_size = {0,0};
int base_line = 0;
char s[100];
int key;
if( f && fgets( imagename, sizeof(imagename)-2, f ))
{
int l = strlen(imagename);
if( l > 0 && imagename[l-1] == '\n' )
imagename[--l] = '\0';
if( l > 0 )
{
if( imagename[0] == '#' )
continue;
view = cvLoadImage( imagename, 1 );
}
}
else if( capture )
{
IplImage* view0 = cvQueryFrame( capture );
if( view0 )
{
view = cvCreateImage( cvGetSize(view0), IPL_DEPTH_8U, view0->nChannels );
if( view0->origin == IPL_ORIGIN_BL )
cvFlip( view0, view, 0 );
else
cvCopy( view0, view );
}
}
if( !view )
{
if( image_points_seq->total > 0 )
{
image_count = image_points_seq->total;
goto calibrate;
}
break;
}
if( flip_vertical )
cvFlip( view, view, 0 );
img_size = cvGetSize(view);
found = cvFindChessboardCorners( view, board_size,
image_points_buf, &count, CV_CALIB_CB_ADAPTIVE_THRESH );
#if 1
// improve the found corners' coordinate accuracy
view_gray = cvCreateImage( cvGetSize(view), 8, 1 );
cvCvtColor( view, view_gray, CV_BGR2GRAY );
cvFindCornerSubPix( view_gray, image_points_buf, count, cvSize(11,11),
cvSize(-1,-1), cvTermCriteria( CV_TERMCRIT_EPS+CV_TERMCRIT_ITER, 30, 0.1 ));
cvReleaseImage( &view_gray );
#endif
if( mode == CAPTURING && found && (f || clock() - prev_timestamp > delay*1e-3*CLOCKS_PER_SEC) )
{
cvSeqPush( image_points_seq, image_points_buf );
prev_timestamp = clock();
blink = !f;
#if 1
if( capture )
{
sprintf( imagename, "view%03d.png", image_points_seq->total - 1 );
cvSaveImage( imagename, view );
}
#endif
}
cvDrawChessboardCorners( view, board_size, image_points_buf, count, found );
cvGetTextSize( "100/100", &font, &text_size, &base_line );
text_origin.x = view->width - text_size.width - 10;
text_origin.y = view->height - base_line - 10;
if( mode == CAPTURING )
{
if( image_count > 0 )
sprintf( s, "%d/%d", image_points_seq ? image_points_seq->total : 0, image_count );
else
sprintf( s, "%d/?", image_points_seq ? image_points_seq->total : 0 );
}
else if( mode == CALIBRATED )
sprintf( s, "Calibrated" );
else
sprintf( s, "Press 'g' to start" );
cvPutText( view, s, text_origin, &font, mode != CALIBRATED ?
CV_RGB(255,0,0) : CV_RGB(0,255,0));
if( blink )
cvNot( view, view );
if( mode == CALIBRATED && undistort_image )
{
IplImage* t = cvCloneImage( view );
cvUndistort2( t, view, &camera, &dist_coeffs );
cvReleaseImage( &t );
}
cvShowImage( "Image View", view );
key = cvWaitKey(capture ? 50 : 500);
if( key == 27 )
break;
if( key == 'u' && mode == CALIBRATED )
undistort_image = !undistort_image;
if( capture && key == 'g' )
{
mode = CAPTURING;
cvClearMemStorage( storage );
image_points_seq = cvCreateSeq( 0, sizeof(CvSeq), elem_size, storage );
}
if( mode == CAPTURING && (unsigned)image_points_seq->total >= (unsigned)image_count )
{
calibrate:
cvReleaseMat( &extr_params );
cvReleaseMat( &reproj_errs );
int code = run_calibration( image_points_seq, img_size, board_size,
square_size, aspect_ratio, flags, &camera, &dist_coeffs, &extr_params,
&reproj_errs, &avg_reproj_err );
// save camera parameters in any case, to catch Inf's/NaN's
save_camera_params( out_filename, image_count, img_size,
board_size, square_size, aspect_ratio, flags,
&camera, &dist_coeffs, write_extrinsics ? extr_params : 0,
write_points ? image_points_seq : 0, reproj_errs, avg_reproj_err );
if( code )
mode = CALIBRATED;
else
mode = DETECTION;
}
if( !view )
break;
cvReleaseImage( &view );
}
if( capture )
cvReleaseCapture( &capture );
if( storage )
cvReleaseMemStorage( &storage );
return 0;
}