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fixed detection of the checkerboards in some extreme cases (ticket #298)

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This commit is contained in:
Vadim Pisarevsky 2010-09-30 20:31:09 +00:00
parent 1061fc6589
commit 70860df574
1 changed files with 7 additions and 4 deletions
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11
modules/calib3d/src/calibinit.cpp
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@ -304,7 +304,7 @@ int cvFindChessboardCorners( const void* arr, CvSize pattern_size,
// This is necessary because some squares simply do not separate properly with a single dilation. However,
// we want to use the minimum number of dilations possible since dilations cause the squares to become smaller,
// making it difficult to detect smaller squares.
for( k = 0; k < 3; k++ )
for( k = 0; k < 6; k++ )
{
for( dilations = min_dilations; dilations <= max_dilations; dilations++ )
{
@ -328,11 +328,11 @@ int cvFindChessboardCorners( const void* arr, CvSize pattern_size,
if( flags & CV_CALIB_CB_ADAPTIVE_THRESH )
{
int block_size = cvRound(prev_sqr_size == 0 ?
MIN(img->cols,img->rows)*0.2 : prev_sqr_size*2.)|1;
MIN(img->cols,img->rows)*(k%2 == 0 ? 0.2 : 0.1): prev_sqr_size*2)|1;
// convert to binary
cvAdaptiveThreshold( img, thresh_img, 255,
CV_ADAPTIVE_THRESH_MEAN_C, CV_THRESH_BINARY, block_size, k*5 );
CV_ADAPTIVE_THRESH_MEAN_C, CV_THRESH_BINARY, block_size, (k/2)*5 );
if (dilations > 0)
cvDilate( thresh_img, thresh_img, 0, dilations-1 );
}
@ -1682,12 +1682,15 @@ icvGenerateQuads( CvCBQuad **out_quads, CvCBCorner **out_corners,
// reject contours with too small perimeter
if( CV_IS_SEQ_HOLE(src_contour) && rect.width*rect.height >= min_size )
{
const int min_approx_level = 2, max_approx_level = MAX_CONTOUR_APPROX;
const int min_approx_level = 1, max_approx_level = MAX_CONTOUR_APPROX;
int approx_level;
for( approx_level = min_approx_level; approx_level <= max_approx_level; approx_level++ )
{
dst_contour = cvApproxPoly( src_contour, sizeof(CvContour), temp_storage,
CV_POLY_APPROX_DP, (float)approx_level );
if( dst_contour->total == 4 )
break;
// we call this again on its own output, because sometimes
// cvApproxPoly() does not simplify as much as it should.
dst_contour = cvApproxPoly( dst_contour, sizeof(CvContour), temp_storage,