opencv/modules/features2d/src/keypoint.cpp

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#include "precomp.hpp"

namespace cv
{
	

void write(FileStorage& fs, const string& objname, const vector<KeyPoint>& keypoints)
{
    WriteStructContext ws(fs, objname, CV_NODE_SEQ + CV_NODE_FLOW);
    
    int i, npoints = (int)keypoints.size();
    for( i = 0; i < npoints; i++ )
    {
        const KeyPoint& kpt = keypoints[i];
        write(fs, kpt.pt.x);
        write(fs, kpt.pt.y);
        write(fs, kpt.size);
        write(fs, kpt.angle);
        write(fs, kpt.response);
        write(fs, kpt.octave);
    }
}


void read(const FileNode& node, vector<KeyPoint>& keypoints)
{
    keypoints.resize(0);
    FileNodeIterator it = node.begin(), it_end = node.end();
    for( ; it != it_end; )
    {
        KeyPoint kpt;
        it >> kpt.pt.x >> kpt.pt.y >> kpt.size >> kpt.angle >> kpt.response >> kpt.octave;
        keypoints.push_back(kpt);
    }
}
    

void KeyPoint::convert(const std::vector<KeyPoint>& keypoints, std::vector<Point2f>& points2f,
                       const vector<int>& keypointIndexes)
{
    if( keypointIndexes.empty() )
    {
        points2f.resize( keypoints.size() );
        for( size_t i = 0; i < keypoints.size(); i++ )
            points2f[i] = keypoints[i].pt;
    }
    else
    {
        points2f.resize( keypointIndexes.size() );
        for( size_t i = 0; i < keypointIndexes.size(); i++ )
        {
            int idx = keypointIndexes[i];
            if( idx >= 0 )
                points2f[i] = keypoints[idx].pt;
            else
            {
                CV_Error( CV_StsBadArg, "keypointIndexes has element < 0. TODO: process this case" );
                //points2f[i] = Point2f(-1, -1);
            }
        }
    }
}
    
void KeyPoint::convert( const std::vector<Point2f>& points2f, std::vector<KeyPoint>& keypoints,
                        float size, float response, int octave, int class_id )
{
    for( size_t i = 0; i < points2f.size(); i++ )
        keypoints[i] = KeyPoint(points2f[i], size, -1, response, octave, class_id);
}

float KeyPoint::overlap( const KeyPoint& kp1, const KeyPoint& kp2 )
{
    const int seedsPerDim = 50;

    float rad1 = kp1.size/2,
          rad2 = kp2.size/2;
    float rad1_2 = rad1*rad1,
          rad2_2 = rad2*rad2;

    Point2f p1 = kp1.pt, p2 = kp2.pt;
    float dist = norm(p1-p2);

    float ovrl = 0.f;
    if( dist < rad1+rad2 ) // circles are intersected
    {
        float minx = min( p1.x - rad1, p2.x - rad2 );
        float maxx = max( p1.x + rad1, p2.x + rad2 );
        float miny = min( p1.y - rad1, p2.y - rad2 );
        float maxy = max( p1.y + rad1, p2.y + rad2 );

        float mina = (maxx-minx) < (maxy-miny) ? (maxx-minx) : (maxy-miny);
        float step = mina/seedsPerDim;
        float bua = 0, bna = 0;

        //compute the areas
        for( float x = minx; x <= maxx; x+=step )
        {
            for( float y = miny; y <= maxy; y+=step )
            {
                float rx1 = x-p1.x;
                float ry1 = y-p1.y;
                float rx2 = x-p2.x;
                float ry2 = y-p2.y;

                //substitution in the equation of a circle
                float c1 = rx1*rx1+ry1*ry1;
                float c2 = rx2*rx2+ry2*ry2;

                if( c1<rad1_2 && c2<rad2_2 ) bna++;
                if( c1<rad1_2 || c2<rad2_2 ) bua++;
            }
        }
        if( bna > 0)
            ovrl = bna/bua;
    }

    return ovrl;
}

}