ProjectionFactorPPP.h

/* ----------------------------------------------------------------------------

 * 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

 * -------------------------------------------------------------------------- */

/**
 * @file ProjectionFactorPPP.h
 * @brief Derived from ProjectionFactor, but estimates body-camera transform
 * in addition to body pose and 3D landmark
 * @author Chris Beall
 */

#pragma once

#include <gtsam/nonlinear/NonlinearFactor.h>
#include <gtsam/nonlinear/NoiseModelFactorN.h>
#include <gtsam/geometry/PinholeCamera.h>
#include <gtsam/geometry/Cal3_S2.h>

namespace gtsam {

  /**
   * Non-linear factor for a constraint derived from a 2D measurement. The calibration is known here.
   * i.e. the main building block for visual SLAM.
   * @ingroup slam
   */
  template<class POSE, class LANDMARK, class CALIBRATION = Cal3_S2>
  class ProjectionFactorPPP: public NoiseModelFactorN<POSE, POSE, LANDMARK> {
  protected:

    // Keep a copy of measurement and calibration for I/O
    Point2 measured_;                    ///< 2D measurement
    std::shared_ptr<CALIBRATION> K_;  ///< shared pointer to calibration object

    // verbosity handling for Cheirality Exceptions
    bool throwCheirality_; ///< If true, rethrows Cheirality exceptions (default: false)
    bool verboseCheirality_; ///< If true, prints text for Cheirality exceptions (default: false)

  public:

    /// shorthand for base class type
    typedef NoiseModelFactor3<POSE, POSE, LANDMARK> Base;

    // Provide access to the Matrix& version of evaluateError:
    using Base::evaluateError;

    /// shorthand for this class
    typedef ProjectionFactorPPP<POSE, LANDMARK, CALIBRATION> This;

    /// shorthand for a smart pointer to a factor
    typedef std::shared_ptr<This> shared_ptr;

    /// Default constructor
  ProjectionFactorPPP() :
      measured_(0.0, 0.0), throwCheirality_(false), verboseCheirality_(false) {
  }

    /**
     * Constructor
     * TODO: Mark argument order standard (keys, measurement, parameters)
     * @param measured is the 2 dimensional location of point in image (the measurement)
     * @param model is the standard deviation
     * @param poseKey is the index of the camera
     * @param transformKey is the index of the body-camera transform
     * @param pointKey is the index of the landmark
     * @param K shared pointer to the constant calibration
     */
    ProjectionFactorPPP(const Point2& measured, const SharedNoiseModel& model,
        Key poseKey, Key transformKey,  Key pointKey,
        const std::shared_ptr<CALIBRATION>& K) :
          Base(model, poseKey, transformKey, pointKey), measured_(measured), K_(K),
          throwCheirality_(false), verboseCheirality_(false) {}

    /**
     * Constructor with exception-handling flags
     * TODO: Mark argument order standard (keys, measurement, parameters)
     * @param measured is the 2 dimensional location of point in image (the measurement)
     * @param model is the standard deviation
     * @param poseKey is the index of the camera
     * @param pointKey is the index of the landmark
     * @param K shared pointer to the constant calibration
     * @param throwCheirality determines whether Cheirality exceptions are rethrown
     * @param verboseCheirality determines whether exceptions are printed for Cheirality
     */
    ProjectionFactorPPP(const Point2& measured, const SharedNoiseModel& model,
        Key poseKey, Key transformKey, Key pointKey,
        const std::shared_ptr<CALIBRATION>& K,
        bool throwCheirality, bool verboseCheirality) :
          Base(model, poseKey, transformKey, pointKey), measured_(measured), K_(K),
          throwCheirality_(throwCheirality), verboseCheirality_(verboseCheirality) {}

    /** Virtual destructor */
    ~ProjectionFactorPPP() override {}

    /// @return a deep copy of this factor
    NonlinearFactor::shared_ptr clone() const override {
      return std::static_pointer_cast<NonlinearFactor>(
          NonlinearFactor::shared_ptr(new This(*this))); }

    /**
     * print
     * @param s optional string naming the factor
     * @param keyFormatter optional formatter useful for printing Symbols
     */
    void print(const std::string& s = "", const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override {
      std::cout << s << "ProjectionFactorPPP, z = ";
      traits<Point2>::Print(measured_);
      Base::print("", keyFormatter);
    }

    /// equals
    bool equals(const NonlinearFactor& p, double tol = 1e-9) const override {
      const This *e = dynamic_cast<const This*>(&p);
      return e
          && Base::equals(p, tol)
          && traits<Point2>::Equals(this->measured_, e->measured_, tol)
          && this->K_->equals(*e->K_, tol);
    }

    /// Evaluate error h(x)-z and optionally derivatives
    Vector evaluateError(const Pose3& pose, const Pose3& transform, const Point3& point,
        OptionalMatrixType H1, OptionalMatrixType H2, OptionalMatrixType H3) const override {
      try {
          if(H1 || H2 || H3) {
            Matrix H0, H02;
            PinholeCamera<CALIBRATION> camera(pose.compose(transform, H0, H02), *K_);
            Point2 reprojectionError(camera.project(point, H1, H3, {}) - measured_);
            *H2 = *H1 * H02;
            *H1 = *H1 * H0;
            return reprojectionError;
          } else {
            PinholeCamera<CALIBRATION> camera(pose.compose(transform), *K_);
            return camera.project(point, H1, H3, {}) - measured_;
          }
      } catch( CheiralityException& e) {
        if (H1) *H1 = Matrix::Zero(2,6);
        if (H2) *H2 = Matrix::Zero(2,6);
        if (H3) *H3 = Matrix::Zero(2,3);
        if (verboseCheirality_)
            std::cout << e.what() << ": Landmark "
                      << DefaultKeyFormatter(this->key3())
                      << " moved behind camera "
                      << DefaultKeyFormatter(this->key1())
                      << std::endl;
        if (throwCheirality_)
          throw e;
      }
      return Vector::Ones(2) * 2.0 * K_->fx();
    }

    /** return the measurement */
    const Point2& measured() const {
      return measured_;
    }

    /** return the calibration object */
    inline const std::shared_ptr<CALIBRATION> calibration() const {
      return K_;
    }

    /** return verbosity */
    inline bool verboseCheirality() const { return verboseCheirality_; }

    /** return flag for throwing cheirality exceptions */
    inline bool throwCheirality() const { return throwCheirality_; }

  private:

#if GTSAM_ENABLE_BOOST_SERIALIZATION    ///
    /// Serialization function
    friend class boost::serialization::access;
    template<class ARCHIVE>
    void serialize(ARCHIVE & ar, const unsigned int /*version*/) {
      ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base);
      ar & BOOST_SERIALIZATION_NVP(measured_);
      ar & BOOST_SERIALIZATION_NVP(K_);
      ar & BOOST_SERIALIZATION_NVP(throwCheirality_);
      ar & BOOST_SERIALIZATION_NVP(verboseCheirality_);
    }
#endif
  };

  /// traits
  template<class POSE, class LANDMARK, class CALIBRATION>
  struct traits<ProjectionFactorPPP<POSE, LANDMARK, CALIBRATION> > :
      public Testable<ProjectionFactorPPP<POSE, LANDMARK, CALIBRATION> > {
  };

} // \ namespace gtsam