/// <summary>
/// Estimates LK optical flow.
/// </summary>
/// <param name="storage">Used storage. Number of pyramid levels is specified within storage. Use storage to gain performance in video* by 2x! </param>
/// <param name="prevFeatures">Previous features.</param>
/// <param name="currFeatures">Current features.</param>
/// <param name="status">Feature status.</param>
/// <param name="windowSize">Aperture size.</param>
/// <param name="iterations">Maximal number of iterations. If <paramref name="minFeatureShift"/> is reached then number of iterations will be lower.</param>
/// <param name="minFeatureShift">Minimal feature shift in horizontal or vertical direction.</param>
/// <param name="minEigenValue">Minimal eigen value.
/// Eigen values could be interpreted as lengths of ellipse's axes.
/// If zero ellipse turn into line therefore there is no corner.</param>
public static void EstimateFlow(PyrLKStorage <TColor> storage,
PointF[] prevFeatures, out PointF[] currFeatures,
out KLTFeatureStatus[] status,
int windowSize = 15, int iterations = 30, float minFeatureShift = 0.1f, float minEigenValue = 0.001f)
{
var initialEstimate = new PointF[prevFeatures.Length];
currFeatures = new PointF[prevFeatures.Length];
status = new KLTFeatureStatus[prevFeatures.Length];
var scaledPrevFeatures = prevFeatures.Apply(x => x.DownScale(storage.PyrLevels));
var usedIndicies = Enumerable.Range(0, prevFeatures.Length).ToArray();
for (int pyrLevel = storage.PyrLevels; pyrLevel >= 0; pyrLevel--)
{
PointF[] levelCurrFeatures;
KLTFeatureStatus[] levelStatus;
LKOpticalFlow <TColor> .EstimateFlow(storage,
scaledPrevFeatures.GetAt(usedIndicies), out levelCurrFeatures, out levelStatus,
windowSize, iterations, minFeatureShift, minEigenValue, initialEstimate, pyrLevel);
//update data
currFeatures.SetAt(usedIndicies, levelCurrFeatures);
status.SetAt(usedIndicies, levelStatus);
if (pyrLevel != 0)
{
scaledPrevFeatures.ApplyInPlace(usedIndicies, x => x.UpScale());
currFeatures.ApplyInPlace(usedIndicies, x => x.UpScale());
initialEstimate = Sub(currFeatures, scaledPrevFeatures);
usedIndicies = getValidFeatureIndicies(status);
}
}
}
