public override IObservable <KeyPointOpticalFlow> Process(IObservable <Tuple <KeyPointCollection, IplImage> > source)
{
return(Observable.Defer(() =>
{
IplImage previousImage = null;
IplImage previousPyramid = null;
IplImage currentPyramid = null;
return source.Select(input =>
{
var previous = input.Item1;
var currentImage = input.Item2;
var currentKeyPoints = new KeyPointCollection(currentImage);
if (previous.Count == 0)
{
return new KeyPointOpticalFlow(previous, currentKeyPoints);
}
if (currentPyramid == null || currentPyramid.Size != currentImage.Size)
{
previousImage = null;
previousPyramid = new IplImage(currentImage.Size, currentImage.Depth, currentImage.Channels);
currentPyramid = new IplImage(currentImage.Size, currentImage.Depth, currentImage.Channels);
}
var maxIterations = MaxIterations;
var epsilon = Epsilon;
var terminationType = TermCriteriaType.None;
if (maxIterations > 0)
{
terminationType |= TermCriteriaType.MaxIter;
}
if (epsilon > 0)
{
terminationType |= TermCriteriaType.Epsilon;
}
var termCriteria = new TermCriteria(terminationType, maxIterations, epsilon);
var flags = previousImage == previous.Image ? LKFlowFlags.PyrAReady : LKFlowFlags.None;
var previousFeatures = new Point2f[previous.Count];
for (int i = 0; i < previousFeatures.Length; i++)
{
previousFeatures[i] = previous[i];
}
var currentFeatures = new Point2f[previousFeatures.Length];
var status = new byte[previousFeatures.Length];
var trackError = new float[previousFeatures.Length];
CV.CalcOpticalFlowPyrLK(
previous.Image,
currentImage,
previousPyramid,
currentPyramid,
previousFeatures,
currentFeatures,
WindowSize,
Level,
status,
trackError,
termCriteria,
flags);
var previousKeyPoints = new KeyPointCollection(previous.Image);
for (int i = 0; i < status.Length; i++)
{
if (status[i] == 0 ||
trackError[i] > MaxError ||
currentFeatures[i].X <0 ||
currentFeatures[i].Y <0 ||
currentFeatures[i].X> currentImage.Width - 1 ||
currentFeatures[i].Y> currentImage.Height - 1)
{
continue;
}
previousKeyPoints.Add(previousFeatures[i]);
currentKeyPoints.Add(currentFeatures[i]);
}
var temp = currentPyramid;
currentPyramid = previousPyramid;
previousPyramid = temp;
previousImage = currentImage;
return new KeyPointOpticalFlow(previousKeyPoints, currentKeyPoints);
});
}));
}
