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);
        write(fs, kpt.class_id);
    }
}


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 >> kpt.class_id;
        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 )
{
    float a = kp1.size * 0.5f;
    float b = kp2.size * 0.5f;
    float a_2 = a * a;
    float b_2 = b * b;

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

    float ovrl = 0.f;

    // one circle is completely encovered by the other => no intersection points!
    if( min( a, b ) + c <= max( a, b ) )
        return min( a_2, b_2 ) / max( a_2, b_2 );

    if( c < a + b ) // circles intersect
    {
        float c_2 = c * c;
        float cosAlpha = ( b_2 + c_2 - a_2 ) / ( kp2.size * c );
        float cosBeta  = ( a_2 + c_2 - b_2 ) / ( kp1.size * c );
        float alpha = acos( cosAlpha );
        float beta = acos( cosBeta );
        float sinAlpha = sin(alpha);
        float sinBeta  = sin(beta);

        float segmentAreaA = a_2 * beta;
        float segmentAreaB = b_2 * alpha;

        float triangleAreaA = a_2 * sinBeta * cosBeta;
        float triangleAreaB = b_2 * sinAlpha * cosAlpha;

        float intersectionArea = segmentAreaA + segmentAreaB - triangleAreaA - triangleAreaB;
        float unionArea = (a_2 + b_2) * (float)CV_PI - intersectionArea;

        ovrl = intersectionArea / unionArea;
    }

    return ovrl;
}

}