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added method to compute overlap for KeyPoint pair

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This commit is contained in:
Maria Dimashova 2010-07-28 10:47:48 +00:00
parent 12e677d456
commit fb2a4a8345
2 changed files with 55 additions and 0 deletions
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6
modules/features2d/include/opencv2/features2d/features2d.hpp
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@ -237,6 +237,12 @@ public:
//! converts vector of points to the vector of keypoints, where each keypoint is assigned the same size and the same orientation
static void convert(const std::vector<Point2f>& points2f, std::vector<KeyPoint>& keypoints,
float size=1, float response=1, int octave=0, int class_id=-1);
//! computes overlap for pair of keypoints;
//! overlap is a ratio between area of keypoint regions intersection and
//! area of keypoint regions union (now keypoint region is circle)
static float overlap(const KeyPoint& kp1, const KeyPoint& kp2);
Point2f pt; //!< coordinates of the keypoints
float size; //!< diameter of the meaningfull keypoint neighborhood
float angle; //!< computed orientation of the keypoint (-1 if not applicable)

49
modules/features2d/src/keypoint.cpp
View File

@ -109,4 +109,53 @@ void KeyPoint::convert( const std::vector<Point2f>& points2f, std::vector<KeyPoi
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;
}
}