Hello, I am using this function calcOpticalFlowFarneback
public static void calcOpticalFlowFarneback(Mat prev, Mat next, Mat flow, double pyr_scale, int levels, int winsize, int iterations, int poly_n, double poly_sigma, int flags) Computes a dense optical flow using the Gunnar Farneback's algorithm.
The function finds an optical flow for each prev pixel using the [Farneback2003] algorithm so that
prev(y,x) ~ next(y + flow(y,x)[1], x + flow(y,x)[0])
Parameters: prev - first 8-bit single-channel input image. next - second input image of the same size and the same type as prev. flow - computed flow image that has the same size as prev and type CV_32FC2. pyr_scale - parameter, specifying the image scale (<1) to build pyramids for each image; pyr_scale=0.5 means a classical pyramid, where each next layer is twice smaller than the previous one. levels - number of pyramid layers including the initial image; levels=1 means that no extra layers are created and only the original images are used. winsize - averaging window size; larger values increase the algorithm robustness to image noise and give more chances for fast motion detection, but yield more blurred motion field. iterations - number of iterations the algorithm does at each pyramid level. poly_n - size of the pixel neighborhood used to find polynomial expansion in each pixel; larger values mean that the image will be approximated with smoother surfaces, yielding more robust algorithm and more blurred motion field, typically poly_n =5 or 7. poly_sigma - standard deviation of the Gaussian that is used to smooth derivatives used as a basis for the polynomial expansion; for poly_n=5, you can set poly_sigma=1.1, for poly_n=7, a good value would be poly_sigma=1.5.
i did not understand how to use the flow matrix! What is it containing!?