lhm.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#ifndef LHM_

#define LHM_

#include <iostream>

//#include <mrpt/math/types_math.h>  // Eigen must be included first via MRPT to
// enable the plugin system
#include <Eigen/Dense>
#include <Eigen/SVD>
#include <Eigen/StdVector>

#define TOL_LHM 0.00001
#define EPSILON_LHM 0.00000001

namespace mrpt::vision::pnp
{
/** \addtogroup pnp Perspective-n-Point pose estimation
 *  \ingroup mrpt_vision_grp
 *  @{
 */

/**
 * @class lhm
 * @author Chandra Mangipudi
 * @date 10/08/16
 * @file lhm.h
 * @brief Lu Hage Mjolsness - Iterative PnP Algorithm (Eigen Implementation
 */
class lhm
{
    Eigen::MatrixXd obj_pts;  //! Object points in Camera Co-ordinate system
    Eigen::MatrixXd img_pts;  //! Image points in pixel co-ordinates
    Eigen::MatrixXd cam_intrinsic;  //! Camera intrinsic matrix
    Eigen::MatrixXd P;  //! Trnaspose of Object points @obj_pts
    Eigen::MatrixXd Q;  //! Transpose of Image points @img_pts

    Eigen::Matrix3d R;  //! Matrix for internal computations
    Eigen::Matrix3d G;  //! Rotation Matrix
    Eigen::Vector3d t;  //! Translation Vector

    std::vector<Eigen::Matrix3d> F;  //! Storage matrix for each point
    double err;  //! Error variable for convergence selection
    double err2;  //! Error variable for convergence selection

    int n;  //! Number of 2d/3d correspondences

   public:
    //! Constructor for the LHM class
    lhm(Eigen::MatrixXd obj_pts_, Eigen::MatrixXd img_pts_,
        Eigen::MatrixXd cam_, int n0);
    //~lhm();

    /**
     * @brief Function to compute pose using LHM PnP algorithm
     * @param R_ Rotation matrix
     * @param t_ Trnaslation Vector
     * @return Success flag
     */
    bool compute_pose(
        Eigen::Ref<Eigen::Matrix3d> R_, Eigen::Ref<Eigen::Vector3d> t_);

    /**
     * @brief Function to compute pose during an iteration
     */
    void absKernel();

    /**
     * @brief Function to estimate translation given an estimated rotation
     * matrix
     */
    void estimate_t();

    /**
     * @brief Transform object points in Body frame (Landmark Frame) to
     * estimated Camera Frame
     */
    void xform();

    /**
     * @brief Iternal Function of quaternion
     * @param q Quaternion
     * @return
     */
    Eigen::Matrix4d qMatQ(Eigen::VectorXd q);

    /**
     * @brief Iternal Function of quaternion
     * @param q Quaternion
     * @return
     */
    Eigen::Matrix4d qMatW(Eigen::VectorXd q);
};

/** @}  */  // end of grouping
}  // namespace mrpt::vision::pnp
#endif