edge_se3_gravity.h

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/*
Copyright (c) 2010-2019, Mathieu Labbe - IntRoLab - Universite de Sherbrooke
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the Universite de Sherbrooke nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

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*/

#ifndef RTAB_G2O_EDGE_SE3_GRAVITY_H_
#define RTAB_G2O_EDGE_SE3_GRAVITY_H_

#include "g2o/core/base_unary_edge.h"
#include "g2o/types/slam3d/vertex_se3.h"

namespace rtabmap {

  class EdgeSE3Gravity : public g2o::BaseUnaryEdge<3, Eigen::Matrix<double, 6, 1>, g2o::VertexSE3> {
  public:
    EIGEN_MAKE_ALIGNED_OPERATOR_NEW
        EdgeSE3Gravity(){
        information().setIdentity();
    }
    virtual bool read(std::istream& is) {return false;} // not implemented
    virtual bool write(std::ostream& os) const {return false;} // not implemented

    // return the error estimate as a 3-vector
    void computeError(){
        const g2o::VertexSE3* v1 = static_cast<const g2o::VertexSE3*>(_vertices[0]);

                Eigen::Vector3d direction = _measurement.head<3>();
                Eigen::Vector3d measurement = _measurement.tail<3>();

                Eigen::Vector3d ea;

                Eigen::Matrix3d t = v1->estimate().linear();
                ea[0] = atan2(t (2, 1), t (2, 2));
                ea[1] = asin(-t (2, 0));
                ea[2] = atan2(t (1, 0), t (0, 0));

                Eigen::Matrix3d rot =
                   (Eigen::AngleAxisd(ea[1], Eigen::Vector3d::UnitY()) *
                        Eigen::AngleAxisd(ea[0], Eigen::Vector3d::UnitX())).toRotationMatrix();

                Eigen::Vector3d estimate = rot * -direction;
                _error = estimate - measurement;

                //printf("%d : measured=%f %f %f est=%f %f %f error=%f %f %f\n", v1->id(),
                //  measurement[0], measurement[1], measurement[2],
                //  estimate[0], estimate[1], estimate[2],
                //  _error[0], _error[1], _error[2]);
    }

    // 6 values:
    // [0:2] Up vector in robot frame
    // [3:5] Observed gravity vector in world frame
    virtual void setMeasurement(const Eigen::Matrix<double, 6, 1>& m){
        _measurement.head<3>() = m.head<3>().normalized();
        _measurement.tail<3>() = m.tail<3>().normalized();
    }
  };
}
#endif