SPSS.h

#ifndef MTF_SPSS_H
#define MTF_SPSS_H

#include "AppearanceModel.h"

_MTF_BEGIN_NAMESPACE

struct SPSSParams : AMParams{
    double k;
    ImageBase *pix_mapper;

    SPSSParams(const AMParams *am_params,
        double _k, 
        ImageBase *_pix_mapper);
    SPSSParams(const SPSSParams *params = nullptr);
};

struct SPSSDist : AMDist{
    typedef bool is_kdtree_distance;
    typedef double ElementType;
    typedef double ResultType;
    SPSSDist(const string &_name, const double _c) : AMDist(_name), c(_c){}
    double operator()(const double* a, const double* b,
        size_t size, double worst_dist = -1) const override;
    double accum_dist(const ElementType& a,
        const ElementType& b, int) const{
        return -(2 * a*b + c) / (a*a + b*b + c);
    }
private:
    const double c;
};

class SPSS : public AppearanceModel{
public:
    typedef SPSSParams ParamType;
    typedef SPSSDist DistType;

    SPSS(const ParamType *spss_params = nullptr, const int _n_channels = 1);

    double getLikelihood() const override;

    //-------------------------------initialize functions------------------------------------//
    void initializePixVals(const Matrix2Xd& init_pts) override;
    void initializeSimilarity() override;
    void initializeGrad() override;
    void initializeHess() override{}

    //-------------------------------update functions------------------------------------//
    void updatePixVals(const Matrix2Xd& curr_pts) override;

    void updateSimilarity(bool prereq_only = true) override;
    void updateInitGrad() override;
    // nothing is done here since curr_grad is same as and shares memory with  curr_pix_diff
    void updateCurrGrad() override;

    void cmptInitHessian(MatrixXd &d2f_dp2, const MatrixXd &dI0_dp) override;
    void cmptInitHessian(MatrixXd &d2f_dp2, const MatrixXd &dI0_dp,
        const MatrixXd &d2I0_dp2) override;

    void cmptCurrHessian(MatrixXd &d2f_dp2, const MatrixXd &dIt_dp) override;
    void cmptCurrHessian(MatrixXd &d2f_dp2, const MatrixXd &dIt_dp,
        const MatrixXd &d2It_dp2) override;

    void cmptSelfHessian(MatrixXd &d2f_dp2, const MatrixXd &dIt_dp) override;
    void cmptSelfHessian(MatrixXd &d2f_dp2, const MatrixXd &dIt_dp,
        const MatrixXd &d2It_dp2) override;

    /*Support for FLANN library*/
    const DistType* getDistFunc() override{
        return new DistType(name, c);
    }
    unsigned int getDistFeatSize() override{ return patch_size; }
    void initializeDistFeat() override{}
    void updateDistFeat(double* feat_addr) override;
    const double* getDistFeat() override{ return getCurrPixVals().data(); }
    void updateDistFeat() override{}

protected:
    ParamType params;

    double c;
    VectorXd f_vec, f_vec_den;
    VectorXd I0_sqr, It_sqr;
};

_MTF_END_NAMESPACE

#endif