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; }