void getOrientation()
{
Ipoint ipt = ipts[index];
float gauss = 0;
float scale = ipt.scale;
int s = COpenSURF.cvRound(scale);
int r = COpenSURF.cvRound(ipt.y);
int c = COpenSURF.cvRound(ipt.x);
List <float> resX = new List <float>();
List <float> resY = new List <float>();
List <float> Ang = new List <float>();
// calculate haar responses for points within radius of 6*scale
for (int i = -6 * s; i <= 6 * s; i += s)
{
for (int j = -6 * s; j <= 6 * s; j += s)
{
if (i * i + j * j < 36 * s * s)
{
gauss = COpenSURF.gaussian(i, j, 2.5f * s);
float _resx = gauss * haarX(r + j, c + i, 4 * s);
float _resy = gauss * haarY(r + j, c + i, 4 * s);
resX.Add(_resx);
resY.Add(_resy);
Ang.Add(COpenSURF.getAngle(_resx, _resy));
}
}
}
// calculate the dominant direction
float sumX, sumY;
float max = 0, old_max = 0, orientation = 0, old_orientation = 0;
float ang1, ang2, ang;
// loop slides pi/3 window around feature point
for (ang1 = 0; ang1 < 2 * pi; ang1 += 0.2f)
{
ang2 = (ang1 + pi / 3.0f > 2 * pi ? ang1 - 5.0f * pi / 3.0f : ang1 + pi / 3.0f);
sumX = sumY = 0;
for (int k = 0; k < Ang.Count; k++)
{
// get angle from the x-axis of the sample point
ang = Ang[k];
// determine whether the point is within the window
if (ang1 < ang2 && ang1 < ang && ang < ang2)
{
sumX += resX[k];
sumY += resY[k];
}
else if (ang2 < ang1 &&
((ang > 0 && ang < ang2) || (ang > ang1 && ang < 2 * pi)))
{
sumX += resX[k];
sumY += resY[k];
}
}
// if the vector produced from this window is longer than all
// previous vectors then this forms the new dominant direction
if (sumX * sumX + sumY * sumY > max)
{
// store second largest orientation
old_max = max;
old_orientation = orientation;
// store largest orientation
max = sumX * sumX + sumY * sumY;
orientation = COpenSURF.getAngle(sumX, sumY);
}
} // for(ang1 = 0; ang1 < 2*pi; ang1+=0.2f)
// check whether there are two dominant orientations based on 0.8 threshold
if (old_max >= 0.8 * max)
{
// assign second largest orientation and push copy onto vector
ipt.orientation = old_orientation;
ipts.Add(ipt);
// Reset ipt to point to correct Ipoint in the vector
ipt = ipts[index];
}
// assign orientation of the dominant response vector
ipt.orientation = orientation;
}
