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#ifndef __OPENCV_GPUOPTFLOW_HPP__
#define __OPENCV_GPUOPTFLOW_HPP__

#ifndef __cplusplus
#  error gpuoptflow.hpp header must be compiled as C++
#endif

#include "opencv2/core/gpu.hpp"

namespace cv { namespace gpu {

class CV_EXPORTS BroxOpticalFlow
{
public:
    BroxOpticalFlow(float alpha_, float gamma_, float scale_factor_, int inner_iterations_, int outer_iterations_, int solver_iterations_) :
        alpha(alpha_), gamma(gamma_), scale_factor(scale_factor_),
        inner_iterations(inner_iterations_), outer_iterations(outer_iterations_), solver_iterations(solver_iterations_)
    {
    }

    //! Compute optical flow
    //! frame0 - source frame (supports only CV_32FC1 type)
    //! frame1 - frame to track (with the same size and type as frame0)
    //! u      - flow horizontal component (along x axis)
    //! v      - flow vertical component (along y axis)
    void operator ()(const GpuMat& frame0, const GpuMat& frame1, GpuMat& u, GpuMat& v, Stream& stream = Stream::Null());

    //! flow smoothness
    float alpha;

    //! gradient constancy importance
    float gamma;

    //! pyramid scale factor
    float scale_factor;

    //! number of lagged non-linearity iterations (inner loop)
    int inner_iterations;

    //! number of warping iterations (number of pyramid levels)
    int outer_iterations;

    //! number of linear system solver iterations
    int solver_iterations;

    GpuMat buf;
};

class CV_EXPORTS PyrLKOpticalFlow
{
public:
    PyrLKOpticalFlow();

    void sparse(const GpuMat& prevImg, const GpuMat& nextImg, const GpuMat& prevPts, GpuMat& nextPts,
        GpuMat& status, GpuMat* err = 0);

    void dense(const GpuMat& prevImg, const GpuMat& nextImg, GpuMat& u, GpuMat& v, GpuMat* err = 0);

    void releaseMemory();

    Size winSize;
    int maxLevel;
    int iters;
    bool useInitialFlow;

private:
    std::vector<GpuMat> prevPyr_;
    std::vector<GpuMat> nextPyr_;

    GpuMat buf_;

    GpuMat uPyr_[2];
    GpuMat vPyr_[2];
};

class CV_EXPORTS FarnebackOpticalFlow
{
public:
    FarnebackOpticalFlow()
    {
        numLevels = 5;
        pyrScale = 0.5;
        fastPyramids = false;
        winSize = 13;
        numIters = 10;
        polyN = 5;
        polySigma = 1.1;
        flags = 0;
    }

    int numLevels;
    double pyrScale;
    bool fastPyramids;
    int winSize;
    int numIters;
    int polyN;
    double polySigma;
    int flags;

    void operator ()(const GpuMat &frame0, const GpuMat &frame1, GpuMat &flowx, GpuMat &flowy, Stream &s = Stream::Null());

    void releaseMemory()
    {
        frames_[0].release();
        frames_[1].release();
        pyrLevel_[0].release();
        pyrLevel_[1].release();
        M_.release();
        bufM_.release();
        R_[0].release();
        R_[1].release();
        blurredFrame_[0].release();
        blurredFrame_[1].release();
        pyramid0_.clear();
        pyramid1_.clear();
    }

private:
    void prepareGaussian(
            int n, double sigma, float *g, float *xg, float *xxg,
            double &ig11, double &ig03, double &ig33, double &ig55);

    void setPolynomialExpansionConsts(int n, double sigma);

    void updateFlow_boxFilter(
            const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat &flowy,
            GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[]);

    void updateFlow_gaussianBlur(
            const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat& flowy,
            GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[]);

    GpuMat frames_[2];
    GpuMat pyrLevel_[2], M_, bufM_, R_[2], blurredFrame_[2];
    std::vector<GpuMat> pyramid0_, pyramid1_;
};

// Implementation of the Zach, Pock and Bischof Dual TV-L1 Optical Flow method
//
// see reference:
//   [1] C. Zach, T. Pock and H. Bischof, "A Duality Based Approach for Realtime TV-L1 Optical Flow".
//   [2] Javier Sanchez, Enric Meinhardt-Llopis and Gabriele Facciolo. "TV-L1 Optical Flow Estimation".
class CV_EXPORTS OpticalFlowDual_TVL1_GPU
{
public:
    OpticalFlowDual_TVL1_GPU();

    void operator ()(const GpuMat& I0, const GpuMat& I1, GpuMat& flowx, GpuMat& flowy);

    void collectGarbage();

    /**
     * Time step of the numerical scheme.
     */
    double tau;

    /**
     * Weight parameter for the data term, attachment parameter.
     * This is the most relevant parameter, which determines the smoothness of the output.
     * The smaller this parameter is, the smoother the solutions we obtain.
     * It depends on the range of motions of the images, so its value should be adapted to each image sequence.
     */
    double lambda;

    /**
     * Weight parameter for (u - v)^2, tightness parameter.
     * It serves as a link between the attachment and the regularization terms.
     * In theory, it should have a small value in order to maintain both parts in correspondence.
     * The method is stable for a large range of values of this parameter.
     */
    double theta;

    /**
     * Number of scales used to create the pyramid of images.
     */
    int nscales;

    /**
     * Number of warpings per scale.
     * Represents the number of times that I1(x+u0) and grad( I1(x+u0) ) are computed per scale.
     * This is a parameter that assures the stability of the method.
     * It also affects the running time, so it is a compromise between speed and accuracy.
     */
    int warps;

    /**
     * Stopping criterion threshold used in the numerical scheme, which is a trade-off between precision and running time.
     * A small value will yield more accurate solutions at the expense of a slower convergence.
     */
    double epsilon;

    /**
     * Stopping criterion iterations number used in the numerical scheme.
     */
    int iterations;

    double scaleStep;

    bool useInitialFlow;

private:
    void procOneScale(const GpuMat& I0, const GpuMat& I1, GpuMat& u1, GpuMat& u2);

    std::vector<GpuMat> I0s;
    std::vector<GpuMat> I1s;
    std::vector<GpuMat> u1s;
    std::vector<GpuMat> u2s;

    GpuMat I1x_buf;
    GpuMat I1y_buf;

    GpuMat I1w_buf;
    GpuMat I1wx_buf;
    GpuMat I1wy_buf;

    GpuMat grad_buf;
    GpuMat rho_c_buf;

    GpuMat p11_buf;
    GpuMat p12_buf;
    GpuMat p21_buf;
    GpuMat p22_buf;

    GpuMat diff_buf;
    GpuMat norm_buf;
};

//! Calculates optical flow for 2 images using block matching algorithm */
CV_EXPORTS void calcOpticalFlowBM(const GpuMat& prev, const GpuMat& curr,
                                  Size block_size, Size shift_size, Size max_range, bool use_previous,
                                  GpuMat& velx, GpuMat& vely, GpuMat& buf,
                                  Stream& stream = Stream::Null());

class CV_EXPORTS FastOpticalFlowBM
{
public:
    void operator ()(const GpuMat& I0, const GpuMat& I1, GpuMat& flowx, GpuMat& flowy, int search_window = 21, int block_window = 7, Stream& s = Stream::Null());

private:
    GpuMat buffer;
    GpuMat extended_I0;
    GpuMat extended_I1;
};

//! Interpolate frames (images) using provided optical flow (displacement field).
//! frame0   - frame 0 (32-bit floating point images, single channel)
//! frame1   - frame 1 (the same type and size)
//! fu       - forward horizontal displacement
//! fv       - forward vertical displacement
//! bu       - backward horizontal displacement
//! bv       - backward vertical displacement
//! pos      - new frame position
//! newFrame - new frame
//! buf      - temporary buffer, will have width x 6*height size, CV_32FC1 type and contain 6 GpuMat;
//!            occlusion masks            0, occlusion masks            1,
//!            interpolated forward flow  0, interpolated forward flow  1,
//!            interpolated backward flow 0, interpolated backward flow 1
//!
CV_EXPORTS void interpolateFrames(const GpuMat& frame0, const GpuMat& frame1,
                                  const GpuMat& fu, const GpuMat& fv,
                                  const GpuMat& bu, const GpuMat& bv,
                                  float pos, GpuMat& newFrame, GpuMat& buf,
                                  Stream& stream = Stream::Null());

CV_EXPORTS void createOpticalFlowNeedleMap(const GpuMat& u, const GpuMat& v, GpuMat& vertex, GpuMat& colors);

}} // namespace cv { namespace gpu {

#endif /* __OPENCV_GPUOPTFLOW_HPP__ */