/// <summary>
/// Use camshift to track the feature
/// </summary>
/// <param name="observedFeatures">The feature found from the observed image</param>
/// <param name="initRegion">The predicted location of the model in the observed image. If not known, use MCvBox2D.Empty as default</param>
/// <param name="priorMask">The mask that should be the same size as the observed image. Contains a priori value of the probability a match can be found. If you are not sure, pass an image fills with 1.0s</param>
/// <returns>If a match is found, the homography projection matrix is returned. Otherwise null is returned</returns>
public HomographyMatrix CamShiftTrack(SURFFeature[] observedFeatures, MCvBox2D initRegion, Image <Gray, Single> priorMask)
{
using (Image <Gray, Single> matchMask = new Image <Gray, Single>(priorMask.Size))
{
#region get the list of matched point on the observed image
Single[, ,] matchMaskData = matchMask.Data;
//Compute the matched features
MatchedSURFFeature[] matchedFeature = _matcher.MatchFeature(observedFeatures, 2, 20);
matchedFeature = VoteForUniqueness(matchedFeature, 0.8);
foreach (MatchedSURFFeature f in matchedFeature)
{
PointF p = f.ObservedFeature.Point.pt;
matchMaskData[(int)p.Y, (int)p.X, 0] = 1.0f / (float)f.SimilarFeatures[0].Distance;
}
#endregion
Rectangle startRegion;
if (initRegion.Equals(MCvBox2D.Empty))
{
startRegion = matchMask.ROI;
}
else
{
startRegion = PointCollection.BoundingRectangle(initRegion.GetVertices());
if (startRegion.IntersectsWith(matchMask.ROI))
{
startRegion.Intersect(matchMask.ROI);
}
}
CvInvoke.cvMul(matchMask.Ptr, priorMask.Ptr, matchMask.Ptr, 1.0);
MCvConnectedComp comp;
MCvBox2D currentRegion;
//Updates the current location
CvInvoke.cvCamShift(matchMask.Ptr, startRegion, new MCvTermCriteria(10, 1.0e-8), out comp, out currentRegion);
#region find the SURF features that belongs to the current Region
MatchedSURFFeature[] featuesInCurrentRegion;
using (MemStorage stor = new MemStorage())
{
Contour <System.Drawing.PointF> contour = new Contour <PointF>(stor);
contour.PushMulti(currentRegion.GetVertices(), Emgu.CV.CvEnum.BACK_OR_FRONT.BACK);
CvInvoke.cvBoundingRect(contour.Ptr, 1); //this is required before calling the InContour function
featuesInCurrentRegion = Array.FindAll(matchedFeature,
delegate(MatchedSURFFeature f)
{ return(contour.InContour(f.ObservedFeature.Point.pt) >= 0); });
}
#endregion
return(GetHomographyMatrixFromMatchedFeatures(VoteForSizeAndOrientation(featuesInCurrentRegion, 1.5, 20)));
}
}
