BetweenFactor.h

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/* ----------------------------------------------------------------------------
 
 * GTSAM Copyright 2010, Georgia Tech Research Corporation,
 * Atlanta, Georgia 30332-0415
 * All Rights Reserved
 * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
 
 * See LICENSE for the license information
 
 * -------------------------------------------------------------------------- */

#pragma once
 
#include <ostream>
 
#include <gtsam/base/Testable.h>
#include <gtsam/base/Lie.h>
#include <gtsam/linear/FixedJacobianFactor.h>
#include <gtsam/nonlinear/NonlinearFactor.h>
#include <gtsam/nonlinear/NoiseModelFactorN.h>
 
namespace gtsam {

  template<class VALUE>
  class BetweenFactor
      : public NoiseModelFactorT<typename traits<VALUE>::TangentVector, VALUE,
                                 VALUE> {
 
    // Check that VALUE type is a testable Lie group
    GTSAM_CONCEPT_ASSERT(IsTestable<VALUE>);
    GTSAM_CONCEPT_ASSERT(IsLieGroup<VALUE>);
 
  public:
 
    typedef VALUE T;
    using ErrorVector = typename traits<VALUE>::TangentVector;
 
  private:
 
    typedef BetweenFactor<VALUE> This;
    typedef NoiseModelFactorT<ErrorVector, VALUE, VALUE> Base;
 
    VALUE measured_; 
 
  public:
 
    // Provide access to the Matrix& version of evaluateError:
    using Base::evaluateError;
 
    // shorthand for a smart pointer to a factor
    typedef typename std::shared_ptr<BetweenFactor> shared_ptr;


    BetweenFactor() {}

    BetweenFactor(Key key1, Key key2, const VALUE& measured,
        const SharedNoiseModel& model = nullptr) :
      Base(noiseModel::validOrDefault(measured, model), key1, key2),
      measured_(measured) {
    }

 
    ~BetweenFactor() override {}

    gtsam::NonlinearFactor::shared_ptr clone() const override {
      return std::static_pointer_cast<gtsam::NonlinearFactor>(
          gtsam::NonlinearFactor::shared_ptr(new This(*this))); }


    void print(
        const std::string& s = "",
        const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override {
      std::cout << s << "BetweenFactor("
          << keyFormatter(this->key1()) << ","
          << keyFormatter(this->key2()) << ")\n";
      traits<T>::Print(measured_, "  measured: ");
      this->noiseModel_->print("  noise model: ");
    }

    bool equals(const NonlinearFactor& expected, double tol=1e-9) const override {
      const This *e =  dynamic_cast<const This*> (&expected);
      return e != nullptr && Base::equals(*e, tol) && traits<T>::Equals(this->measured_, e->measured_, tol);
    }


    ErrorVector evaluateError(const T& p1, const T& p2,
                        OptionalMatrixType H1, OptionalMatrixType H2) const override {
      T hx = traits<T>::Between(p1, p2, H1, H2); // h(x)
      // manifold equivalent of h(x)-z -> log(z,h(x))
#ifdef GTSAM_SLOW_BUT_CORRECT_BETWEENFACTOR
      if constexpr (internal::HasLocalJacobians<T>::value) {
        if (H1 || H2) {
          typename traits<T>::ChartJacobian::Jacobian Hlocal;
          Vector error =
              traits<T>::Local(measured_, hx, OptionalNone, &Hlocal);
          if (H1) *H1 = Hlocal * (*H1);
          if (H2) *H2 = Hlocal * (*H2);
          return error;
        }
      }
#endif
      return traits<T>::Local(measured_, hx);
    }


    const VALUE& measured() const {
      return measured_;
    }

 
  private:
 
#if GTSAM_ENABLE_BOOST_SERIALIZATION
    friend class boost::serialization::access;
    template<class ARCHIVE>
    void serialize(ARCHIVE & ar, const unsigned int /*version*/) {
      // NoiseModelFactor2 instead of NoiseModelFactorN for backward compatibility
      ar & boost::serialization::make_nvp("NoiseModelFactor2",
          boost::serialization::base_object<Base>(*this));
      ar & BOOST_SERIALIZATION_NVP(measured_);
    }
#endif
  }; // \class BetweenFactor

  template<class VALUE>
  struct traits<BetweenFactor<VALUE> > : public Testable<BetweenFactor<VALUE> > {};

  template<class VALUE>
  class BetweenConstraint : public BetweenFactor<VALUE> {
  public:
    typedef std::shared_ptr<BetweenConstraint<VALUE> > shared_ptr;

    BetweenConstraint(const VALUE& measured, Key key1, Key key2, double mu = 1000.0) :
      BetweenFactor<VALUE>(key1, key2, measured,
                           noiseModel::Constrained::All(traits<VALUE>::GetDimension(measured), std::abs(mu)))
    {}
 
  private:

#if GTSAM_ENABLE_BOOST_SERIALIZATION
    friend class boost::serialization::access;
    template<class ARCHIVE>
    void serialize(ARCHIVE & ar, const unsigned int /*version*/) {
      ar & boost::serialization::make_nvp("BetweenFactor",
          boost::serialization::base_object<BetweenFactor<VALUE> >(*this));
    }
#endif
  }; // \class BetweenConstraint

  template<class VALUE>
  struct traits<BetweenConstraint<VALUE> > : public Testable<BetweenConstraint<VALUE> > {};
 
}