/// <summary>
///
/// </summary>
/// <param name="objectKeypoints"></param>
/// <param name="objectDescriptors"></param>
/// <param name="imageKeypoints"></param>
/// <param name="imageDescriptors"></param>
/// <returns></returns>
private static int[] FindPairs(CvSeq <CvSURFPoint> objectKeypoints, CvSeq <float> objectDescriptors, CvSeq <CvSURFPoint> imageKeypoints, CvSeq <float> imageDescriptors)
{
CvSeqReader <float> reader = new CvSeqReader <float>();
CvSeqReader <CvSURFPoint> kreader = new CvSeqReader <CvSURFPoint>();
Cv.StartReadSeq(objectDescriptors, reader);
Cv.StartReadSeq(objectKeypoints, kreader);
List <int> ptpairs = new List <int>();
for (int i = 0; i < objectDescriptors.Total; i++)
{
CvSURFPoint kp = CvSURFPoint.FromPtr(kreader.Ptr);
IntPtr descriptor = reader.Ptr;
Cv.NEXT_SEQ_ELEM(kreader.Seq.ElemSize, kreader);
Cv.NEXT_SEQ_ELEM(reader.Seq.ElemSize, reader);
int nearestNeighbor = NaiveNearestNeighbor(descriptor, kp.Laplacian, imageKeypoints, imageDescriptors);
if (nearestNeighbor >= 0)
{
ptpairs.Add(i);
ptpairs.Add(nearestNeighbor);
}
}
return(ptpairs.ToArray());
}
/// <summary>
///
/// </summary>
/// <param name="vec">Cではconst float*</param>
/// <param name="laplacian"></param>
/// <param name="model_keypoints"></param>
/// <param name="model_descriptors"></param>
/// <returns></returns>
private static int NaiveNearestNeighbor(IntPtr vec, int laplacian, CvSeq <CvSURFPoint> model_keypoints, CvSeq <float> model_descriptors)
{
int length = (int)(model_descriptors.ElemSize / sizeof(float));
int neighbor = -1;
double dist1 = 1e6, dist2 = 1e6;
CvSeqReader <float> reader = new CvSeqReader <float>();
CvSeqReader <CvSURFPoint> kreader = new CvSeqReader <CvSURFPoint>();
Cv.StartReadSeq(model_keypoints, kreader, false);
Cv.StartReadSeq(model_descriptors, reader, false);
IntPtr mvec;
CvSURFPoint kp;
double d;
for (int i = 0; i < model_descriptors.Total; i++)
{
// const CvSURFPoint* kp = (const CvSURFPoint*)kreader.ptr; が結構曲者。
// OpenCvSharpの構造体はFromPtrでポインタからインスタンス生成できるようにしてるので、こう書ける。
kp = CvSURFPoint.FromPtr(kreader.Ptr);
// まともにキャストする場合はこんな感じか
// CvSURFPoint kp = (CvSURFPoint)Marshal.PtrToStructure(kreader.Ptr, typeof(CvSURFPoint));
mvec = reader.Ptr;
Cv.NEXT_SEQ_ELEM(kreader.Seq.ElemSize, kreader);
Cv.NEXT_SEQ_ELEM(reader.Seq.ElemSize, reader);
if (laplacian != kp.Laplacian)
{
continue;
}
d = CompareSurfDescriptors(vec, mvec, dist2, length);
if (d < dist1)
{
dist2 = dist1;
dist1 = d;
neighbor = i;
}
else if (d < dist2)
{
dist2 = d;
}
}
if (dist1 < 0.6 * dist2)
{
return(neighbor);
}
else
{
return(-1);
}
}