115 lines
4.0 KiB
C++
115 lines
4.0 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010-2020, 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 TranslationRecovery.h
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* @author Frank Dellaert
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* @date March 2020
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* @brief test recovering translations when rotations are given.
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*/
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#include <gtsam/geometry/Unit3.h>
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#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
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#include <gtsam/nonlinear/Values.h>
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#include <map>
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#include <utility>
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namespace gtsam {
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// Set up an optimization problem for the unknown translations Ti in the world
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// coordinate frame, given the known camera attitudes wRi with respect to the
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// world frame, and a set of (noisy) translation directions of type Unit3,
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// w_aZb. The measurement equation is
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// w_aZb = Unit3(Tb - Ta) (1)
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// i.e., w_aZb is the translation direction from frame A to B, in world
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// coordinates. Although Unit3 instances live on a manifold, following
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// Wilson14eccv_1DSfM.pdf error we compute the *chordal distance* in the
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// ambient world coordinate frame.
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//
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// It is clear that we cannot recover the scale, nor the absolute position,
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// so the gauge freedom in this case is 3 + 1 = 4. We fix these by taking fixing
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// the translations Ta and Tb associated with the first measurement w_aZb,
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// clamping them to their initial values as given to this method. If no initial
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// values are given, we use the origin for Tb and set Tb to make (1) come
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// through, i.e.,
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// Tb = s * wRa * Point3(w_aZb) (2)
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// where s is an arbitrary scale that can be supplied, default 1.0. Hence, two
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// versions are supplied below corresponding to whether we have initial values
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// or not.
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class TranslationRecovery {
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public:
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using KeyPair = std::pair<Key, Key>;
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using TranslationEdges = std::map<KeyPair, Unit3>;
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private:
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TranslationEdges relativeTranslations_;
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LevenbergMarquardtParams params_;
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public:
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/**
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* @brief Construct a new Translation Recovery object
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*
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* @param relativeTranslations the relative translations, in world coordinate
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* frames, indexed in a map by a pair of Pose keys.
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* @param lmParams (optional) gtsam::LavenbergMarquardtParams that can be
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* used to modify the parameters for the LM optimizer. By default, uses the
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* default LM parameters.
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*/
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TranslationRecovery(const TranslationEdges& relativeTranslations,
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const LevenbergMarquardtParams& lmParams = LevenbergMarquardtParams())
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: relativeTranslations_(relativeTranslations), params_(lmParams) {
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params_.setVerbosityLM("Summary");
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}
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/**
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* @brief Build the factor graph to do the optimization.
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*
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* @return NonlinearFactorGraph
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*/
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NonlinearFactorGraph buildGraph() const;
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/**
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* @brief Add priors on ednpoints of first measurement edge.
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*
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* @param scale scale for first relative translation which fixes gauge.
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* @param graph factor graph to which prior is added.
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*/
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void addPrior(const double scale, NonlinearFactorGraph* graph) const;
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/**
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* @brief Create random initial translations.
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*
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* @return Values
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*/
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Values initalizeRandomly() const;
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/**
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* @brief Build and optimize factor graph.
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*
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* @param scale scale for first relative translation which fixes gauge.
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* @return Values
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*/
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Values run(const double scale = 1.0) const;
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/**
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* @brief Simulate translation direction measurements
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*
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* @param poses SE(3) ground truth poses stored as Values
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* @param edges pairs (a,b) for which a measurement w_aZb will be generated.
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* @return TranslationEdges map from a KeyPair to the simulated Unit3
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* translation direction measurement between the cameras in KeyPair.
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*/
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static TranslationEdges SimulateMeasurements(
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const Values& poses, const std::vector<KeyPair>& edges);
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};
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} // namespace gtsam
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