TranslationFactor.h

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

 * GTSAM Copyright 2010-2020, 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 <gtsam/geometry/Point3.h>
#include <gtsam/geometry/Unit3.h>
#include <gtsam/linear/NoiseModel.h>
#include <gtsam/nonlinear/NonlinearFactor.h>

namespace gtsam {

class TranslationFactor : public NoiseModelFactorN<Point3, Point3> {
 private:
  typedef NoiseModelFactorN<Point3, Point3> Base;
  Point3 measured_w_aZb_;

 public:

  // Provide access to the Matrix& version of evaluateError:
  using NoiseModelFactor2<Point3, Point3>::evaluateError;

  TranslationFactor() {}

  TranslationFactor(Key a, Key b, const Unit3& w_aZb,
                    const SharedNoiseModel& noiseModel)
      : Base(noiseModel, a, b), measured_w_aZb_(w_aZb.point3()) {}

  Vector evaluateError(
      const Point3& Ta, const Point3& Tb,
      OptionalMatrixType H1,
      OptionalMatrixType H2) const override {
    const Point3 dir = Tb - Ta;
    Matrix33 H_predicted_dir;
    const Point3 predicted = normalize(dir, H1 || H2 ? &H_predicted_dir : nullptr);
    if (H1) *H1 = -H_predicted_dir;
    if (H2) *H2 = H_predicted_dir;
    return predicted - measured_w_aZb_;
  }

 private:
#ifdef 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(
        "Base", boost::serialization::base_object<Base>(*this));
  }
#endif
};  // \ TranslationFactor
}  // namespace gtsam