/modules/calib3d/src/calibinit.cpp

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/************************************************************************************\
    This is improved variant of chessboard corner detection algorithm that
    uses a graph of connected quads. It is based on the code contributed
    by Vladimir Vezhnevets and Philip Gruebele.
    Here is the copyright notice from the original Vladimir's code:
    ===============================================================

    The algorithms developed and implemented by Vezhnevets Vldimir
    aka Dead Moroz (vvp@graphics.cs.msu.ru)
    See http://graphics.cs.msu.su/en/research/calibration/opencv.html
    for detailed information.

    Reliability additions and modifications made by Philip Gruebele.
    <a href="mailto:pgruebele@cox.net">pgruebele@cox.net</a>

    Some further improvements for detection of partially ocluded boards at non-ideal
    lighting conditions have been made by Alex Bovyrin and Kurt Kolonige

\************************************************************************************/

#include "precomp.hpp"
#include "opencv2/imgproc/imgproc_c.h"
#include "opencv2/calib3d/calib3d_c.h"
#include "circlesgrid.hpp"
#include <stdarg.h>

//#define ENABLE_TRIM_COL_ROW

//#define DEBUG_CHESSBOARD
#ifdef DEBUG_CHESSBOARD
#  include "opencv2/opencv_modules.hpp"
#  ifdef HAVE_OPENCV_HIGHGUI
#    include "opencv2/highgui.hpp"
#  else
#    undef DEBUG_CHESSBOARD
#  endif
#endif
#ifdef DEBUG_CHESSBOARD
static int PRINTF( const char* fmt, ... )
{
    va_list args;
    va_start(args, fmt);
    return vprintf(fmt, args);
}
#else
static int PRINTF( const char*, ... )
{
    return 0;
}
#endif


//=====================================================================================
// Implementation for the enhanced calibration object detection
//=====================================================================================

#define MAX_CONTOUR_APPROX  7

struct CvContourEx
{
    CV_CONTOUR_FIELDS()
    int counter;
};

//=====================================================================================

/// Corner info structure
/** This structure stores information about the chessboard corner.*/
struct CvCBCorner
{
    CvPoint2D32f pt; // Coordinates of the corner
    int row;         // Board row index
    int count;       // Number of neighbor corners
    struct CvCBCorner* neighbors[4]; // Neighbor corners

    float meanDist(int *_n) const
    {
        float sum = 0;
        int n = 0;
        for( int i = 0; i < 4; i++ )
        {
            if( neighbors[i] )
            {
                float dx = neighbors[i]->pt.x - pt.x;
                float dy = neighbors[i]->pt.y - pt.y;
                sum += sqrt(dx*dx + dy*dy);
                n++;
            }
        }
        if(_n)
            *_n = n;
        return sum/MAX(n,1);
    }
};

//=====================================================================================
/// Quadrangle contour info structure
/** This structure stores information about the chessboard quadrange.*/
struct CvCBQuad
{
    int count;      // Number of quad neighbors
    int group_idx;  // quad group ID
    int row, col;   // row and column of this quad
    bool ordered;   // true if corners/neighbors are ordered counter-clockwise
    float edge_len; // quad edge len, in pix^2
    // neighbors and corners are synced, i.e., neighbor 0 shares corner 0
    CvCBCorner *corners[4]; // Coordinates of quad corners
    struct CvCBQuad *neighbors[4]; // Pointers of quad neighbors
};

//=====================================================================================

//static CvMat* debug_img = 0;

static int icvGenerateQuads( CvCBQuad **quads, CvCBCorner **corners,
                             CvMemStorage *storage, CvMat *image, int flags );

/*static int
icvGenerateQuadsEx( CvCBQuad **out_quads, CvCBCorner **out_corners,
    CvMemStorage *storage, CvMat *image, CvMat *thresh_img, int dilation, int flags );*/

static void icvFindQuadNeighbors( CvCBQuad *quads, int quad_count );

static int icvFindConnectedQuads( CvCBQuad *quads, int quad_count,
                                  CvCBQuad **quad_group, int group_idx,
                                  CvMemStorage* storage );

static int icvCheckQuadGroup( CvCBQuad **quad_group, int count,
                              CvCBCorner **out_corners, CvSize pattern_size );

static int icvCleanFoundConnectedQuads( int quad_count,
                CvCBQuad **quads, CvSize pattern_size );

static int icvOrderFoundConnectedQuads( int quad_count, CvCBQuad **quads,
           int *all_count, CvCBQuad **all_quads, CvCBCorner **corners,
           CvSize pattern_size, CvMemStorage* storage );

static void icvOrderQuad(CvCBQuad *quad, CvCBCorner *corner, int common);

#ifdef ENABLE_TRIM_COL_ROW
static int icvTrimCol(CvCBQuad **quads, int count, int col, int dir);

static int icvTrimRow(CvCBQuad **quads, int count, int row, int dir);
#endif

static int icvAddOuterQuad(CvCBQuad *quad, CvCBQuad **quads, int quad_count,
                    CvCBQuad **all_quads, int all_count, CvCBCorner **corners);

static void icvRemoveQuadFromGroup(CvCBQuad **quads, int count, CvCBQuad *q0);

static int icvCheckBoardMonotony( CvPoint2D32f* corners, CvSize pattern_size );

#if 0
static void
icvCalcAffineTranf2D32f(CvPoint2D32f* pts1, CvPoint2D32f* pts2, int count, CvMat* affine_trans)
{
    int i, j;
    int real_count = 0;
    for( j = 0; j < count; j++ )
    {
        if( pts1[j].x >= 0 ) real_count++;
    }
    if(real_count < 3) return;
    cv::Ptr<CvMat> xy = cvCreateMat( 2*real_count, 6, CV_32FC1 );
    cv::Ptr<CvMat> uv = cvCreateMat( 2*real_count, 1, CV_32FC1 );
    //estimate affine transfromation
    for( i = 0, j = 0; j < count; j++ )
    {
        if( pts1[j].x >= 0 )
        {
            CV_MAT_ELEM( *xy, float, i*2+1, 2 ) = CV_MAT_ELEM( *xy, float, i*2, 0 ) = pts2[j].x;
            CV_MAT_ELEM( *xy, float, i*2+1, 3 ) = CV_MAT_ELEM( *xy, float, i*2, 1 ) = pts2[j].y;
            CV_MAT_ELEM( *xy, float, i*2, 2 ) = CV_MAT_ELEM( *xy, float, i*2, 3 ) = CV_MAT_ELEM( *xy, float, i*2, 5 ) = \
                CV_MAT_ELEM( *xy, float, i*2+1, 0 ) = CV_MAT_ELEM( *xy, float, i*2+1, 1 ) = CV_MAT_ELEM( *xy, float, i*2+1, 4 ) = 0;
            CV_MAT_ELEM( *xy, float, i*2, 4 ) = CV_MAT_ELEM( *xy, float, i*2+1, 5 ) = 1;
            CV_MAT_ELEM( *uv, float, i*2, 0 ) = pts1[j].x;
            CV_MAT_ELEM( *uv, float, i*2+1, 0 ) = pts1[j].y;
            i++;
        }
    }

    cvSolve( xy, uv, affine_trans, CV_SVD );
}
#endif

CV_IMPL
int cvFindChessboardCorners( const void* arr, CvSize pattern_size,
                             CvPoint2D32f* out_corners, int* out_corner_count,
                             int flags )
{
    int found = 0;
    CvCBQuad *quads = 0, **quad_group = 0;
    CvCBCorner *corners = 0, **corner_group = 0;

    try
    {
    int k = 0;
    const int min_dilations = 0;
    const int max_dilations = 7;
    cv::Ptr<CvMat> norm_img, thresh_img;
#ifdef DEBUG_CHESSBOARD
    cv::Ptr<IplImage> dbg_img;
    cv::Ptr<IplImage> dbg1_img;
    cv::Ptr<IplImage> dbg2_img;
#endif
    cv::Ptr<CvMemStorage> storage;

    CvMat stub, *img = (CvMat*)arr;

    int expected_corners_num = (pattern_size.width/2+1)*(pattern_size.height/2+1);

    int prev_sqr_size = 0;

    if( out_corner_count )
        *out_corner_count = 0;

    IplImage _img;
    int check_chessboard_result;
    int quad_count = 0, group_idx = 0, dilations = 0;

    img = cvGetMat( img, &stub );
    //debug_img = img;

    if( CV_MAT_DEPTH( img->type ) != CV_8U || CV_MAT_CN( img->type ) == 2 )
        CV_Error( CV_StsUnsupportedFormat, "Only 8-bit grayscale or color images are supported" );

    if( pattern_size.width <= 2 || pattern_size.height <= 2 )
        CV_Error( CV_StsOutOfRange, "Both width and height of the pattern should have bigger than 2" );

    if( !out_corners )
        CV_Error( CV_StsNullPtr, "Null pointer to corners" );

    storage.reset(cvCreateMemStorage(0));
    thresh_img.reset(cvCreateMat( img->rows, img->cols, CV_8UC1 ));

#ifdef DEBUG_CHESSBOARD
    dbg_img = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 3 );
    dbg1_img = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 3 );
    dbg2_img = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 3 );
#endif

    if( CV_MAT_CN(img->type) != 1 || (flags & CV_CALIB_CB_NORMALIZE_IMAGE) )
    {
        // equalize the input image histogram -
        // that should make the contrast between "black" and "white" areas big enough
        norm_img.reset(cvCreateMat( img->rows, img->cols, CV_8UC1 ));

        if( CV_MAT_CN(img->type) != 1 )
        {
            cvCvtColor( img, norm_img, CV_BGR2GRAY );
            img = norm_img;
        }

        if( flags & CV_CALIB_CB_NORMALIZE_IMAGE )
        {
            cvEqualizeHist( img, norm_img );
            img = norm_img;
        }
    }

    if( flags & CV_CALIB_CB_FAST_CHECK)
    {
        cvGetImage(img, &_img);
        check_chessboard_result = cvCheckChessboard(&_img, pattern_size);
        if(check_chessboard_result <= 0)
        {
            return 0;
        }
    }

    // Try our standard "1" dilation, but if the pattern is not found, iterate the whole procedure with higher dilations.
    // 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 < 6; k++ )
    {
        for( dilations = min_dilations; dilations <= max_dilations; dilations++ )
        {
            if (found)
                break;      // already found it

            cvFree(&quads);
            cvFree(&corners);

            /*if( k == 1 )
            {
                //Pattern was not found using binarization
                // Run multi-level quads extraction
                // In case one-level binarization did not give enough number of quads
                CV_CALL( quad_count = icvGenerateQuadsEx( &quads, &corners, storage, img, thresh_img, dilations, flags ));
                PRINTF("EX quad count: %d/%d\n", quad_count, expected_corners_num);
            }
            else*/
            {
                // convert the input grayscale image to binary (black-n-white)
                if( flags & CV_CALIB_CB_ADAPTIVE_THRESH )
                {
                    int block_size = cvRound(prev_sqr_size == 0 ?
                        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/2)*5 );
                    if (dilations > 0)
                        cvDilate( thresh_img, thresh_img, 0, dilations-1 );
                }
                else
                {
                    // Make dilation before the thresholding.
                    // It splits chessboard corners
                    //cvDilate( img, thresh_img, 0, 1 );

                    // empiric threshold level
                    double mean = cvAvg( img ).val[0];
                    int thresh_level = cvRound( mean - 10 );
                    thresh_level = MAX( thresh_level, 10 );

                    cvThreshold( img, thresh_img, thresh_level, 255, CV_THRESH_BINARY );
                    cvDilate( thresh_img, thresh_img, 0, dilations );
                }

#ifdef DEBUG_CHESSBOARD
                cvCvtColor(thresh_img,dbg_img,CV_GRAY2BGR);
#endif

                // So we can find rectangles that go to the edge, we draw a white line around the image edge.
                // Otherwise FindContours will miss those clipped rectangle contours.
                // The border color will be the image mean, because otherwise we risk screwing up filters like cvSmooth()...
                cvRectangle( thresh_img, cvPoint(0,0), cvPoint(thresh_img->cols-1,
                    thresh_img->rows-1), CV_RGB(255,255,255), 3, 8);

                quad_count = icvGenerateQuads( &quads, &corners, storage, thresh_img, flags );

                PRINTF("Quad count: %d/%d\n", quad_count, expected_corners_num);
            }


#ifdef DEBUG_CHESSBOARD
            cvCopy(dbg_img, dbg1_img);
            cvNamedWindow("all_quads", 1);
            // copy corners to temp array
            for(int i = 0; i < quad_count; i++ )
            {
                for (int k=0; k<4; k++)
                {
                    CvPoint2D32f pt1, pt2;
                    CvScalar color = CV_RGB(30,255,30);
                    pt1 = quads[i].corners[k]->pt;
                    pt2 = quads[i].corners[(k+1)%4]->pt;
                    pt2.x = (pt1.x + pt2.x)/2;
                    pt2.y = (pt1.y + pt2.y)/2;
                    if (k>0)
                        color = CV_RGB(200,200,0);
                    cvLine( dbg1_img, cvPointFrom32f(pt1), cvPointFrom32f(pt2), color, 3, 8);
                }
            }


            cvShowImage("all_quads", (IplImage*)dbg1_img);
            cvWaitKey();
#endif

            if( quad_count <= 0 )
                continue;

            // Find quad's neighbors
            icvFindQuadNeighbors( quads, quad_count );

            // allocate extra for adding in icvOrderFoundQuads
            cvFree(&quad_group);
            cvFree(&corner_group);
            quad_group = (CvCBQuad**)cvAlloc( sizeof(quad_group[0]) * (quad_count+quad_count / 2));
            corner_group = (CvCBCorner**)cvAlloc( sizeof(corner_group[0]) * (quad_count+quad_count / 2)*4 );

            for( group_idx = 0; ; group_idx++ )
            {
                int count = 0;
                count = icvFindConnectedQuads( quads, quad_count, quad_group, group_idx, storage );

                int icount = count;
                if( count == 0 )
                    break;

                // order the quad corners globally
                // maybe delete or add some
                PRINTF("Starting ordering of inner quads\n");
                count = icvOrderFoundConnectedQuads(count, quad_group, &quad_count, &quads, &corners,
                    pattern_size, storage );
                PRINTF("Orig count: %d  After ordering: %d\n", icount, count);


#ifdef DEBUG_CHESSBOARD
                cvCopy(dbg_img,dbg2_img);
                cvNamedWindow("connected_group", 1);
                // copy corners to temp array
                for(int i = 0; i < quad_count; i++ )
                {
                    if (quads[i].group_idx == group_idx)
                        for (int k=0; k<4; k++)
                        {
                            CvPoint2D32f pt1, pt2;
                            CvScalar color = CV_RGB(30,255,30);
                            if (quads[i].ordered)
                                color = CV_RGB(255,30,30);
                            pt1 = quads[i].corners[k]->pt;
                            pt2 = quads[i].corners[(k+1)%4]->pt;
                            pt2.x = (pt1.x + pt2.x)/2;
                            pt2.y = (pt1.y + pt2.y)/2;
                            if (k>0)
                                color = CV_RGB(200,200,0);
                            cvLine( dbg2_img, cvPointFrom32f(pt1), cvPointFrom32f(pt2), color, 3, 8);
                        }
                }
                cvShowImage("connected_group", (IplImage*)dbg2_img);
                cvWaitKey();
#endif

                if (count == 0)
                    continue;       // haven't found inner quads


                // If count is more than it should be, this will remove those quads
                // which cause maximum deviation from a nice square pattern.
                count = icvCleanFoundConnectedQuads( count, quad_group, pattern_size );
                PRINTF("Connected group: %d  orig count: %d cleaned: %d\n", group_idx, icount, count);

                count = icvCheckQuadGroup( quad_group, count, corner_group, pattern_size );
                PRINTF("Connected group: %d  count: %d  cleaned: %d\n", group_idx, icount, count);

                {
                int n = count > 0 ? pattern_size.width * pattern_size.height : -count;
                n = MIN( n, pattern_size.width * pattern_size.height );
                float sum_dist = 0;
                int total = 0;

                for(int i = 0; i < n; i++ )
                {
                    int ni = 0;
                    float avgi = corner_group[i]->meanDist(&ni);
                    sum_dist += avgi*ni;
                    total += ni;
                }
                prev_sqr_size = cvRound(sum_dist/MAX(total, 1));

                if( count > 0 || (out_corner_count && -count > *out_corner_count) )
                {
                    // copy corners to output array
                    for(int i = 0; i < n; i++ )
                        out_corners[i] = corner_group[i]->pt;

                    if( out_corner_count )
                        *out_corner_count = n;

                    if( count == pattern_size.width*pattern_size.height &&
                        icvCheckBoardMonotony( out_corners, pattern_size ))
                    {
                        found = 1;
                        break;
                    }
                }
                }
            }
        }//dilations
    }//

    if( found )
        found = icvCheckBoardMonotony( out_corners, pattern_size );

    // check that none of the found corners is too close to the image boundary
    if( found )
    {
        const int BORDER = 8;
        for( k = 0; k < pattern_size.width*pattern_size.height; k++ )
        {
            if( out_corners[k].x <= BORDER || out_corners[k].x > img->cols - BORDER ||
                out_corners[k].y <= BORDER || out_corners[k].y > img->rows - BORDER )
                break;
        }

        found = k == pattern_size.width*pattern_size.height;
    }

    if( found && pattern_size.height % 2 == 0 && pattern_size.width % 2 == 0 )
    {
        int last_row = (pattern_size.height-1)*pattern_size.width;
        double dy0 = out_corners[last_row].y - out_corners[0].y;
        if( dy0 < 0 )
        {
            int n = pattern_size.width*pattern_size.height;
            for(int i = 0; i < n/2; i++ )
            {
                CvPoint2D32f temp;
                CV_SWAP(out_corners[i], out_corners[n-i-1], temp);
            }
        }
    }

    if( found )
    {
        cv::Ptr<CvMat> gray;
        if( CV_MAT_CN(img->type) != 1 )
        {
            gray.reset(cvCreateMat(img->rows, img->cols, CV_8UC1));
            cvCvtColor(img, gray, CV_BGR2GRAY);
        }
        else
        {
            gray.reset(cvCloneMat(img));
        }
        int wsize = 2;
        cvFindCornerSubPix( gray, out_corners, pattern_size.width*pattern_size.height,
            cvSize(wsize, wsize), cvSize(-1,-1), cvTermCriteria(CV_TERMCRIT_EPS+CV_TERMCRIT_ITER, 15, 0.1));
    }
    }
    catch(...)
    {
        cvFree(&quads);
        cvFree(&corners);
        cvFree(&quad_group);
        cvFree(&corner_group);
        throw;
    }

    cvFree(&quads);
    cvFree(&corners);
    cvFree(&quad_group);
    cvFree(&corner_group);
    return found;
}

//
// Checks that each board row and column is pretty much monotonous curve:
// It analyzes each row and each column of the chessboard as following:
//    for each corner c lying between end points in the same row/column it checks that
//    the point projection to the line segment (a,b) is lying between projections
//    of the neighbor corners in the same row/column.
//
// This function has been created as temporary workaround for the bug in current implementation
// of cvFindChessboardCornes that produces absolutely unordered sets of corners.
//

static int
icvCheckBoardMonotony( CvPoint2D32f* corners, CvSize pattern_size )
{
    int i, j, k;

    for( k = 0; k < 2; k++ )
    {
        for( i = 0; i < (k == 0 ? pattern_size.height : pattern_size.width); i++ )
        {
            CvPoint2D32f a = k == 0 ? corners[i*pattern_size.width] : corners[i];
            CvPoint2D32f b = k == 0 ? corners[(i+1)*pattern_size.width-1] :
                corners[(pattern_size.height-1)*pattern_size.width + i];
            float prevt = 0, dx0 = b.x - a.x, dy0 = b.y - a.y;
            if( fabs(dx0) + fabs(dy0) < FLT_EPSILON )
                return 0;
            for( j = 1; j < (k == 0 ? pattern_size.width : pattern_size.height) - 1; j++ )
            {
                CvPoint2D32f c = k == 0 ? corners[i*pattern_size.width + j] :
                    corners[j*pattern_size.width + i];
                float t = ((c.x - a.x)*dx0 + (c.y - a.y)*dy0)/(dx0*dx0 + dy0*dy0);
                if( t < prevt || t > 1 )
                    return 0;
                prevt = t;
            }
        }
    }

    return 1;
}

//
// order a group of connected quads
// order of corners:
//   0 is top left
//   clockwise from there
// note: "top left" is nominal, depends on initial ordering of starting quad
//   but all other quads are ordered consistently
//
// can change the number of quads in the group
// can add quads, so we need to have quad/corner arrays passed in
//

static int
icvOrderFoundConnectedQuads( int quad_count, CvCBQuad **quads,
        int *all_count, CvCBQuad **all_quads, CvCBCorner **corners,
        CvSize pattern_size, CvMemStorage* storage )
{
    cv::Ptr<CvMemStorage> temp_storage(cvCreateChildMemStorage( storage ));
    CvSeq* stack = cvCreateSeq( 0, sizeof(*stack), sizeof(void*), temp_storage );

    // first find an interior quad
    CvCBQuad *start = NULL;
    for (int i=0; i<quad_count; i++)
    {
        if (quads[i]->count == 4)
        {
            start = quads[i];
            break;
        }
    }

    if (start == NULL)
        return 0;   // no 4-connected quad

    // start with first one, assign rows/cols
    int row_min = 0, col_min = 0, row_max=0, col_max = 0;

    std::map<int, int> col_hist;
    std::map<int, int> row_hist;

    cvSeqPush(stack, &start);
    start->row = 0;
    start->col = 0;
    start->ordered = true;

    // Recursively order the quads so that all position numbers (e.g.,
    // 0,1,2,3) are in the at the same relative corner (e.g., lower right).

    while( stack->total )
    {
        CvCBQuad* q;
        cvSeqPop( stack, &q );
        int col = q->col;
        int row = q->row;
        col_hist[col]++;
        row_hist[row]++;

        // check min/max
        if (row > row_max) row_max = row;
        if (row < row_min) row_min = row;
        if (col > col_max) col_max = col;
        if (col < col_min) col_min = col;

        for(int i = 0; i < 4; i++ )
        {
            CvCBQuad *neighbor = q->neighbors[i];
            switch(i)   // adjust col, row for this quad
            {           // start at top left, go clockwise
            case 0:
                row--; col--; break;
            case 1:
                col += 2; break;
            case 2:
                row += 2;   break;
            case 3:
                col -= 2; break;
            }

            // just do inside quads
            if (neighbor && neighbor->ordered == false && neighbor->count == 4)
            {
                PRINTF("col: %d  row: %d\n", col, row);
                icvOrderQuad(neighbor, q->corners[i], (i+2)%4); // set in order
                neighbor->ordered = true;
                neighbor->row = row;
                neighbor->col = col;
                cvSeqPush( stack, &neighbor );
            }
        }
    }

    for (int i=col_min; i<=col_max; i++)
        PRINTF("HIST[%d] = %d\n", i, col_hist[i]);

    // analyze inner quad structure
    int w = pattern_size.width - 1;
    int h = pattern_size.height - 1;
    int drow = row_max - row_min + 1;
    int dcol = col_max - col_min + 1;

    // normalize pattern and found quad indices
    if ((w > h && dcol < drow) ||
        (w < h && drow < dcol))
    {
        h = pattern_size.width - 1;
        w = pattern_size.height - 1;
    }

    PRINTF("Size: %dx%d  Pattern: %dx%d\n", dcol, drow, w, h);

    // check if there are enough inner quads
    if (dcol < w || drow < h)   // found enough inner quads?
    {
        PRINTF("Too few inner quad rows/cols\n");
        return 0;   // no, return
    }
#ifdef ENABLE_TRIM_COL_ROW
    // too many columns, not very common
    if (dcol == w+1)    // too many, trim
    {
        PRINTF("Trimming cols\n");
        if (col_hist[col_max] > col_hist[col_min])
        {
            PRINTF("Trimming left col\n");
            quad_count = icvTrimCol(quads,quad_count,col_min,-1);
        }
        else
        {
            PRINTF("Trimming right col\n");
            quad_count = icvTrimCol(quads,quad_count,col_max,+1);
        }
    }

    // too many rows, not very common
    if (drow == h+1)    // too many, trim
    {
        PRINTF("Trimming rows\n");
        if (row_hist[row_max] > row_hist[row_min])
        {
            PRINTF("Trimming top row\n");
            quad_count = icvTrimRow(quads,quad_count,row_min,-1);
        }
        else
        {
            PRINTF("Trimming bottom row\n");
            quad_count = icvTrimRow(quads,quad_count,row_max,+1);
        }
    }
#endif

    // check edges of inner quads
    // if there is an outer quad missing, fill it in
    // first order all inner quads
    int found = 0;
    for (int i=0; i<quad_count; i++)
    {
        if (quads[i]->count == 4)
        {   // ok, look at neighbors
            int col = quads[i]->col;
            int row = quads[i]->row;
            for (int j=0; j<4; j++)
            {
                switch(j)   // adjust col, row for this quad
                {       // start at top left, go clockwise
                case 0:
                    row--; col--; break;
                case 1:
                    col += 2; break;
                case 2:
                    row += 2;   break;
                case 3:
                    col -= 2; break;
                }
                CvCBQuad *neighbor = quads[i]->neighbors[j];
                if (neighbor && !neighbor->ordered && // is it an inner quad?
                    col <= col_max && col >= col_min &&
                    row <= row_max && row >= row_min)
                {
                    // if so, set in order
                    PRINTF("Adding inner: col: %d  row: %d\n", col, row);
                    found++;
                    icvOrderQuad(neighbor, quads[i]->corners[j], (j+2)%4);
                    neighbor->ordered = true;
                    neighbor->row = row;
                    neighbor->col = col;
                }
            }
        }
    }

    // if we have found inner quads, add corresponding outer quads,
    //   which are missing
    if (found > 0)
    {
        PRINTF("Found %d inner quads not connected to outer quads, repairing\n", found);
        for (int i=0; i<quad_count; i++)
        {
            if (quads[i]->count < 4 && quads[i]->ordered)
            {
                int added = icvAddOuterQuad(quads[i],quads,quad_count,all_quads,*all_count,corners);
                *all_count += added;
                quad_count += added;
            }
        }
    }


    // final trimming of outer quads
    if (dcol == w && drow == h) // found correct inner quads
    {
        PRINTF("Inner bounds ok, check outer quads\n");
        int rcount = quad_count;
        for (int i=quad_count-1; i>=0; i--) // eliminate any quad not connected to
            // an ordered quad
        {
            if (quads[i]->ordered == false)
            {
                bool outer = false;
                for (int j=0; j<4; j++) // any neighbors that are ordered?
                {
                    if (quads[i]->neighbors[j] && quads[i]->neighbors[j]->ordered)
                        outer = true;
                }
                if (!outer) // not an outer quad, eliminate
                {
                    PRINTF("Removing quad %d\n", i);
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]);
                    rcount--;
                }
            }

        }
        return rcount;
    }

    return 0;
}


// add an outer quad
// looks for the neighbor of <quad> that isn't present,
//   tries to add it in.
// <quad> is ordered

static int
icvAddOuterQuad( CvCBQuad *quad, CvCBQuad **quads, int quad_count,
        CvCBQuad **all_quads, int all_count, CvCBCorner **corners )

{
    int added = 0;
    for (int i=0; i<4; i++) // find no-neighbor corners
    {
        if (!quad->neighbors[i])    // ok, create and add neighbor
        {
            int j = (i+2)%4;
            PRINTF("Adding quad as neighbor 2\n");
            CvCBQuad *q = &(*all_quads)[all_count];
            memset( q, 0, sizeof(*q) );
            added++;
            quads[quad_count] = q;
            quad_count++;

            // set neighbor and group id
            quad->neighbors[i] = q;
            quad->count += 1;
            q->neighbors[j] = quad;
            q->group_idx = quad->group_idx;
            q->count = 1;   // number of neighbors
            q->ordered = false;
            q->edge_len = quad->edge_len;

            // make corners of new quad
            // same as neighbor quad, but offset
            CvPoint2D32f pt = quad->corners[i]->pt;
            CvCBCorner* corner;
            float dx = pt.x - quad->corners[j]->pt.x;
            float dy = pt.y - quad->corners[j]->pt.y;
            for (int k=0; k<4; k++)
            {
                corner = &(*corners)[all_count*4+k];
                pt = quad->corners[k]->pt;
                memset( corner, 0, sizeof(*corner) );
                corner->pt = pt;
                q->corners[k] = corner;
                corner->pt.x += dx;
                corner->pt.y += dy;
            }
            // have to set exact corner
            q->corners[j] = quad->corners[i];

            // now find other neighbor and add it, if possible
            if (quad->neighbors[(i+3)%4] &&
                quad->neighbors[(i+3)%4]->ordered &&
                quad->neighbors[(i+3)%4]->neighbors[i] &&
                quad->neighbors[(i+3)%4]->neighbors[i]->ordered )
            {
                CvCBQuad *qn = quad->neighbors[(i+3)%4]->neighbors[i];
                q->count = 2;
                q->neighbors[(j+1)%4] = qn;
                qn->neighbors[(i+1)%4] = q;
                qn->count += 1;
                // have to set exact corner
                q->corners[(j+1)%4] = qn->corners[(i+1)%4];
            }

            all_count++;
        }
    }
    return added;
}


// trimming routines
#ifdef ENABLE_TRIM_COL_ROW
static int
icvTrimCol(CvCBQuad **quads, int count, int col, int dir)
{
    int rcount = count;
    // find the right quad(s)
    for (int i=0; i<count; i++)
    {
#ifdef DEBUG_CHESSBOARD
        if (quads[i]->ordered)
            PRINTF("index: %d  cur: %d\n", col, quads[i]->col);
#endif
        if (quads[i]->ordered && quads[i]->col == col)
        {
            if (dir == 1)
            {
                if (quads[i]->neighbors[1])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[1]);
                    rcount--;
                }
                if (quads[i]->neighbors[2])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[2]);
                    rcount--;
                }
            }
            else
            {
                if (quads[i]->neighbors[0])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[0]);
                    rcount--;
                }
                if (quads[i]->neighbors[3])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[3]);
                    rcount--;
                }
            }

        }
    }
    return rcount;
}

static int
icvTrimRow(CvCBQuad **quads, int count, int row, int dir)
{
    int i, rcount = count;
    // find the right quad(s)
    for (i=0; i<count; i++)
    {
#ifdef DEBUG_CHESSBOARD
        if (quads[i]->ordered)
            PRINTF("index: %d  cur: %d\n", row, quads[i]->row);
#endif
        if (quads[i]->ordered && quads[i]->row == row)
        {
            if (dir == 1)   // remove from bottom
            {
                if (quads[i]->neighbors[2])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[2]);
                    rcount--;
                }
                if (quads[i]->neighbors[3])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[3]);
                    rcount--;
                }
            }
            else    // remove from top
            {
                if (quads[i]->neighbors[0])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[0]);
                    rcount--;
                }
                if (quads[i]->neighbors[1])
                {
                    icvRemoveQuadFromGroup(quads,rcount,quads[i]->neighbors[1]);
                    rcount--;
                }
            }

        }
    }
    return rcount;
}
#endif

//
// remove quad from quad group
//

static void
icvRemoveQuadFromGroup(CvCBQuad **quads, int count, CvCBQuad *q0)
{
    int i, j;
    // remove any references to this quad as a neighbor
    for(i = 0; i < count; i++ )
    {
        CvCBQuad *q = quads[i];
        for(j = 0; j < 4; j++ )
        {
            if( q->neighbors[j] == q0 )
            {
                q->neighbors[j] = 0;
                q->count--;
                for(int k = 0; k < 4; k++ )
                    if( q0->neighbors[k] == q )
                    {
                        q0->neighbors[k] = 0;
                        q0->count--;
                        break;
                    }
                    break;
            }
        }
    }

    // remove the quad
    for(i = 0; i < count; i++ )
    {
        CvCBQuad *q = quads[i];
        if (q == q0)
        {
            quads[i] = quads[count-1];
            break;
        }
    }
}

//
// put quad into correct order, where <corner> has value <common>
//

static void
icvOrderQuad(CvCBQuad *quad, CvCBCorner *corner, int common)
{
    // find the corner
    int tc;
    for (tc=0; tc<4; tc++)
        if (quad->corners[tc]->pt.x == corner->pt.x &&
            quad->corners[tc]->pt.y == corner->pt.y)
            break;

    // set corner order
    // shift
    while (tc != common)
    {
        // shift by one
        CvCBCorner *tempc;
        CvCBQuad *tempq;
        tempc = quad->corners[3];
        tempq = quad->neighbors[3];
        for (int i=3; i>0; i--)
        {
            quad->corners[i] = quad->corners[i-1];
            quad->neighbors[i] = quad->neighbors[i-1];
        }
        quad->corners[0] = tempc;
        quad->neighbors[0] = tempq;
        tc++;
        tc = tc%4;
    }
}


// if we found too many connect quads, remove those which probably do not belong.
static int
icvCleanFoundConnectedQuads( int quad_count, CvCBQuad **quad_group, CvSize pattern_size )
{
    CvPoint2D32f center;
    int i, j, k;
    // number of quads this pattern should contain
    int count = ((pattern_size.width + 1)*(pattern_size.height + 1) + 1)/2;

    // if we have more quadrangles than we should,
    // try to eliminate duplicates or ones which don't belong to the pattern rectangle...
    if( quad_count <= count )
        return quad_count;

    // create an array of quadrangle centers
    cv::AutoBuffer<CvPoint2D32f> centers( quad_count );
    cv::Ptr<CvMemStorage> temp_storage(cvCreateMemStorage(0));

    for( i = 0; i < quad_count; i++ )
    {
        CvPoint2D32f ci;
        CvCBQuad* q = quad_group[i];

        for( j = 0; j < 4; j++ )
        {
            CvPoint2D32f pt = q->corners[j]->pt;
            ci.x += pt.x;
            ci.y += pt.y;
        }

        ci.x *= 0.25f;
        ci.y *= 0.25f;

        centers[i] = ci;
        center.x += ci.x;
        center.y += ci.y;
    }
    center.x /= quad_count;
    center.y /= quad_count;

    // If we still have more quadrangles than we should,
    // we try to eliminate bad ones based on minimizing the bounding box.
    // We iteratively remove the point which reduces the size of
    // the bounding box of the blobs the most
    // (since we want the rectangle to be as small as possible)
    // remove the quadrange that causes the biggest reduction
    // in pattern size until we have the correct number
    for( ; quad_count > count; quad_count-- )
    {
        double min_box_area = DBL_MAX;
        int skip, min_box_area_index = -1;
        CvCBQuad *q0, *q;

        // For each point, calculate box area without that point
        for( skip = 0; skip < quad_count; skip++ )
        {
            // get bounding rectangle
            CvPoint2D32f temp = centers[skip]; // temporarily make index 'skip' the same as
            centers[skip] = center;            // pattern center (so it is not counted for convex hull)
            CvMat pointMat = cvMat(1, quad_count, CV_32FC2, centers);
            CvSeq *hull = cvConvexHull2( &pointMat, temp_storage, CV_CLOCKWISE, 1 );
            centers[skip] = temp;
            double hull_area = fabs(cvContourArea(hull, CV_WHOLE_SEQ));

            // remember smallest box area
            if( hull_area < min_box_area )
            {
                min_box_area = hull_area;
                min_box_area_index = skip;
            }
            cvClearMemStorage( temp_storage );
        }

        q0 = quad_group[min_box_area_index];

        // remove any references to this quad as a neighbor
        for( i = 0; i < quad_count; i++ )
        {
            q = quad_group[i];
            for( j = 0; j < 4; j++ )
            {
                if( q->neighbors[j] == q0 )
                {
                    q->neighbors[j] = 0;
                    q->count--;
                    for( k = 0; k < 4; k++ )
                        if( q0->neighbors[k] == q )
                        {
                            q0->neighbors[k] = 0;
                            q0->count--;
                            break;
                        }
                    break;
                }
            }
        }

        // remove the quad
        quad_count--;
        quad_group[min_box_area_index] = quad_group[quad_count];
        centers[min_box_area_index] = centers[quad_count];
    }

    return quad_count;
}

//=====================================================================================

static int
icvFindConnectedQuads( CvCBQuad *quad, int quad_count, CvCBQuad **out_group,
                       int group_idx, CvMemStorage* storage )
{
    cv::Ptr<CvMemStorage> temp_storage(cvCreateChildMemStorage( storage ));
    CvSeq* stack = cvCreateSeq( 0, sizeof(*stack), sizeof(void*), temp_storage );
    int i, count = 0;

    // Scan the array for a first unlabeled quad
    for( i = 0; i < quad_count; i++ )
    {
        if( quad[i].count > 0 && quad[i].group_idx < 0)
            break;
    }

    // Recursively find a group of connected quads starting from the seed quad[i]
    if( i < quad_count )
    {
        CvCBQuad* q = &quad[i];
        cvSeqPush( stack, &q );
        out_group[count++] = q;
        q->group_idx = group_idx;
        q->ordered = false;

        while( stack->total )
        {
            cvSeqPop( stack, &q );
            for( i = 0; i < 4; i++ )
            {
                CvCBQuad *neighbor = q->neighbors[i];
                if( neighbor && neighbor->count > 0 && neighbor->group_idx < 0 )
                {
                    cvSeqPush( stack, &neighbor );
                    out_group[count++] = neighbor;
                    neighbor->group_idx = group_idx;
                    neighbor->ordered = false;
                }
            }
        }
    }

    return count;
}


//=====================================================================================

static int
icvCheckQuadGroup( CvCBQuad **quad_group, int quad_count,
                   CvCBCorner **out_corners, CvSize pattern_size )
{
    const int ROW1 = 1000000;
    const int ROW2 = 2000000;
    const int ROW_ = 3000000;
    int result = 0;
    int i, out_corner_count = 0, corner_count = 0;
    std::vector<CvCBCorner*> corners(quad_count*4);

    int j, k, kk;
    int width = 0, height = 0;
    int hist[5] = {0,0,0,0,0};
    CvCBCorner* first = 0, *first2 = 0, *right, *cur, *below, *c;

    // build dual graph, which vertices are internal quad corners
    // and two vertices are connected iff they lie on the same quad edge
    for( i = 0; i < quad_count; i++ )
    {
        CvCBQuad* q = quad_group[i];
        /*CvScalar color = q->count == 0 ? cvScalar(0,255,255) :
                         q->count == 1 ? cvScalar(0,0,255) :
                         q->count == 2 ? cvScalar(0,255,0) :
                         q->count == 3 ? cvScalar(255,255,0) :
                                         cvScalar(255,0,0);*/

        for( j = 0; j < 4; j++ )
        {
            //cvLine( debug_img, cvPointFrom32f(q->corners[j]->pt), cvPointFrom32f(q->corners[(j+1)&3]->pt), color, 1, CV_AA, 0 );
            if( q->neighbors[j] )
            {
                CvCBCorner *a = q->corners[j], *b = q->corners[(j+1)&3];
                // mark internal corners that belong to:
                //   - a quad with a single neighbor - with ROW1,
                //   - a quad with two neighbors     - with ROW2
                // make the rest of internal corners with ROW_
                int row_flag = q->count == 1 ? ROW1 : q->count == 2 ? ROW2 : ROW_;

                if( a->row == 0 )
                {
                    corners[corner_count++] = a;
                    a->row = row_flag;
                }
                else if( a->row > row_flag )
                    a->row = row_flag;

                if( q->neighbors[(j+1)&3] )
                {
                    if( a->count >= 4 || b->count >= 4 )
                        goto finalize;
                    for( k = 0; k < 4; k++ )
                    {
                        if( a->neighbors[k] == b )
                            goto finalize;
                        if( b->neighbors[k] == a )
                            goto finalize;
                    }
                    a->neighbors[a->count++] = b;
                    b->neighbors[b->count++] = a;
                }
            }
        }
    }

    if( corner_count != pattern_size.width*pattern_size.height )
        goto finalize;

    for( i = 0; i < corner_count; i++ )
    {
        int n = corners[i]->count;
        assert( 0 <= n && n <= 4 );
        hist[n]++;
        if( !first && n == 2 )
        {
            if( corners[i]->row == ROW1 )
                first = corners[i];
            else if( !first2 && corners[i]->row == ROW2 )
                first2 = corners[i];
        }
    }

    // start with a corner that belongs to a quad with a signle neighbor.
    // if we do not have such, start with a corner of a quad with two neighbors.
    if( !first )
        first = first2;

    if( !first || hist[0] != 0 || hist[1] != 0 || hist[2] != 4 ||
        hist[3] != (pattern_size.width + pattern_size.height)*2 - 8 )
        goto finalize;

    cur = first;
    right = below = 0;
    out_corners[out_corner_count++] = cur;

    for( k = 0; k < 4; k++ )
    {
        c = cur->neighbors[k];
        if( c )
        {
            if( !right )
                right = c;
            else if( !below )
                below = c;
        }
    }

    if( !right || (right->count != 2 && right->count != 3) ||
        !below || (below->count != 2 && below->count != 3) )
        goto finalize;

    cur->row = 0;
    //cvCircle( debug_img, cvPointFrom32f(cur->pt), 3, cvScalar(0,255,0), -1, 8, 0 );

    first = below; // remember the first corner in the next row
    // find and store the first row (or column)
    for(j=1;;j++)
    {
        right->row = 0;
        out_corners[out_corner_count++] = right;
        //cvCircle( debug_img, cvPointFrom32f(right->pt), 3, cvScalar(0,255-j*10,0), -1, 8, 0 );
        if( right->count == 2 )
            break;
        if( right->count != 3 || out_corner_count >= MAX(pattern_size.width,pattern_size.height) )
            goto finalize;
        cur = right;
        for( k = 0; k < 4; k++ )
        {
            c = cur->neighbors[k];
            if( c && c->row > 0 )
            {
                for( kk = 0; kk < 4; kk++ )
                {
                    if( c->neighbors[kk] == below )
                        break;
                }
                if( kk < 4 )
                    below = c;
                else
                    right = c;
            }
        }
    }

    width = out_corner_count;
    if( width == pattern_size.width )
        height = pattern_size.height;
    else if( width == pattern_size.height )
        height = pattern_size.width;
    else
        goto finalize;

    // find and store all the other rows
    for( i = 1; ; i++ )
    {
        if( !first )
            break;
        cur = first;
        first = 0;
        for( j = 0;; j++ )
        {
            cur->row = i;
            out_corners[out_corner_count++] = cur;
            //cvCircle( debug_img, cvPointFrom32f(cur->pt), 3, cvScalar(0,0,255-j*10), -1, 8, 0 );
            if( cur->count == 2 + (i < height-1) && j > 0 )
                break;

            right = 0;

            // find a neighbor that has not been processed yet
            // and that has a neighbor from the previous row
            for( k = 0; k < 4; k++ )
            {
                c = cur->neighbors[k];
                if( c && c->row > i )
                {
                    for( kk = 0; kk < 4; kk++ )
                    {
                        if( c->neighbors[kk] && c->neighbors[kk]->row == i-1 )
                            break;
                    }
                    if( kk < 4 )
                    {
                        right = c;
                        if( j > 0 )
                            break;
                    }
                    else if( j == 0 )
                        first = c;
                }
            }
            if( !right )
                goto finalize;
            cur = right;
        }

        if( j != width - 1 )
            goto finalize;
    }

    if( out_corner_count != corner_count )
        goto finalize;

    // check if we need to transpose the board
    if( width != pattern_size.width )
    {
        CV_SWAP( width, height, k );

        memcpy( &corners[0], out_corners, corner_count*sizeof(corners[0]) );
        for( i = 0; i < height; i++ )
            for( j = 0; j < width; j++ )
                out_corners[i*width + j] = corners[j*height + i];
    }

    // check if we need to revert the order in each row
    {
        CvPoint2D32f p0 = out_corners[0]->pt, p1 = out_corners[pattern_size.width-1]->pt,
                     p2 = out_corners[pattern_size.width]->pt;
        if( (p1.x - p0.x)*(p2.y - p1.y) - (p1.y - p0.y)*(p2.x - p1.x) < 0 )
        {
            if( width % 2 == 0 )
            {
                for( i = 0; i < height; i++ )
                    for( j = 0; j < width/2; j++ )
                        CV_SWAP( out_corners[i*width+j], out_corners[i*width+width-j-1], c );
            }
            else
            {
                for( j = 0; j < width; j++ )
                    for( i = 0; i < height/2; i++ )
                        CV_SWAP( out_corners[i*width+j], out_corners[(height - i - 1)*width+j], c );
            }
        }
    }

    result = corner_count;

finalize:

    if( result <= 0 )
    {
        corner_count = MIN( corner_count, pattern_size.width*pattern_size.height );
        for( i = 0; i < corner_count; i++ )
            out_corners[i] = corners[i];
        result = -corner_co…