122 lines
4.0 KiB
C++
122 lines
4.0 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/**
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* @file AntiFactor.h
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* @author Stephen Williams
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**/
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#pragma once
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#include <ostream>
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#include <gtsam/nonlinear/NonlinearFactor.h>
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#include <gtsam/linear/GaussianFactor.h>
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namespace gtsam {
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/**
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* A class for downdating an existing factor from a graph. The AntiFactor returns the same
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* linearized Hessian matrices of the original factor, but with the opposite sign. This effectively
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* cancels out any affects of the original factor during optimization."
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* @ingroup slam
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*/
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class AntiFactor: public NonlinearFactor {
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private:
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typedef AntiFactor This;
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typedef NonlinearFactor Base;
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typedef NonlinearFactor::shared_ptr sharedFactor;
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sharedFactor factor_;
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public:
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// shorthand for a smart pointer to a factor
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typedef std::shared_ptr<AntiFactor> shared_ptr;
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/** default constructor - only use for serialization */
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AntiFactor() {}
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/** constructor - Creates the equivalent AntiFactor from an existing factor */
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AntiFactor(NonlinearFactor::shared_ptr factor) : Base(factor->keys()), factor_(factor) {}
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~AntiFactor() override {}
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/// @return a deep copy of this factor
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gtsam::NonlinearFactor::shared_ptr clone() const override {
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return std::static_pointer_cast<gtsam::NonlinearFactor>(
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gtsam::NonlinearFactor::shared_ptr(new This(*this))); }
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/** implement functions needed for Testable */
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/** print */
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void print(const std::string& s, const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override {
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std::cout << s << "AntiFactor version of:" << std::endl;
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factor_->print(s, keyFormatter);
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}
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/** equals */
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bool equals(const NonlinearFactor& expected, double tol=1e-9) const override {
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const This *e = dynamic_cast<const This*> (&expected);
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return e != nullptr && Base::equals(*e, tol) && this->factor_->equals(*e->factor_, tol);
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}
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/** implement functions needed to derive from Factor */
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/**
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* Calculate the error of the factor
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* For the AntiFactor, this will have the same magnitude of the original factor,
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* but the opposite sign.
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*/
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double error(const Values& c) const override { return -factor_->error(c); }
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/** get the dimension of the factor (same as the original factor) */
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size_t dim() const override { return factor_->dim(); }
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/**
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* Checks whether this factor should be used based on a set of values.
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* The AntiFactor will have the same 'active' profile as the original factor.
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*/
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bool active(const Values& c) const override { return factor_->active(c); }
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/**
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* Linearize to a GaussianFactor. The AntiFactor always returns a Hessian Factor
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* with the same Hessian matrices as the original factor (even if the original factor
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* returns a Jacobian instead of a full Hessian), but with the opposite sign. This
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* effectively cancels the effect of the original factor on the factor graph.
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*/
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std::shared_ptr<GaussianFactor> linearize(const Values& c) const override {
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// Generate the linearized factor from the contained nonlinear factor
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GaussianFactor::shared_ptr gaussianFactor = factor_->linearize(c);
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// return the negated version of the factor
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return gaussianFactor->negate();
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}
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private:
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#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
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/** Serialization function */
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friend class boost::serialization::access;
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template<class ARCHIVE>
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void serialize(ARCHIVE & ar, const unsigned int /*version*/) {
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ar & boost::serialization::make_nvp("AntiFactor",
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boost::serialization::base_object<Base>(*this));
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ar & BOOST_SERIALIZATION_NVP(factor_);
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}
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#endif
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}; // \class AntiFactor
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} /// namespace gtsam
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