/// <summary>
/// Constructs a pyramid which can be used as input for calcOpticalFlowPyrLK
/// </summary>
/// <param name="img">8-bit input image.</param>
/// <param name="pyramid">output pyramid.</param>
/// <param name="winSize">window size of optical flow algorithm.
/// Must be not less than winSize argument of calcOpticalFlowPyrLK().
/// It is needed to calculate required padding for pyramid levels.</param>
/// <param name="maxLevel">0-based maximal pyramid level number.</param>
/// <param name="withDerivatives">set to precompute gradients for the every pyramid level.
/// If pyramid is constructed without the gradients then calcOpticalFlowPyrLK() will
/// calculate them internally.</param>
/// <param name="pyrBorder">the border mode for pyramid layers.</param>
/// <param name="derivBorder">the border mode for gradients.</param>
/// <param name="tryReuseInputImage">put ROI of input image into the pyramid if possible.
/// You can pass false to force data copying.</param>
/// <returns>number of levels in constructed pyramid. Can be less than maxLevel.</returns>
public static int BuildOpticalFlowPyramid(
InputArray img, out Mat[] pyramid,
Size winSize, int maxLevel,
bool withDerivatives = true,
BorderType pyrBorder = BorderType.Reflect101,
BorderType derivBorder = BorderType.Constant,
bool tryReuseInputImage = true)
{
if (img == null)
{
throw new ArgumentNullException(nameof(img));
}
img.ThrowIfDisposed();
using (var pyramidVec = new VectorOfMat())
{
int result = NativeMethods.video_buildOpticalFlowPyramid1(
img.CvPtr, pyramidVec.CvPtr, winSize, maxLevel, withDerivatives ? 1 : 0,
(int)pyrBorder, (int)derivBorder, tryReuseInputImage ? 1 : 0);
pyramid = pyramidVec.ToArray();
return(result);
}
}
