119 lines
3.5 KiB
C++
119 lines
3.5 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 Event.h
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* @brief Space-time event
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* @author Frank Dellaert
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* @author Jay Chakravarty
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* @date December 2014
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*/
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#pragma once
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#include <gtsam/geometry/Point3.h>
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#include <gtsam_unstable/dllexport.h>
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#include <cmath>
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#include <iosfwd>
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#include <string>
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namespace gtsam {
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/**
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* A space-time event models an event that happens at a certain 3D location, at
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* a certain time. One use for it is in sound-based or UWB-ranging tracking or
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* SLAM, where we have "time of arrival" measurements at a set of sensors. The
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* TOA functor below provides a measurement function for those applications.
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*/
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class GTSAM_UNSTABLE_EXPORT Event {
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double time_; ///< Time event was generated
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Point3 location_; ///< Location at time event was generated
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public:
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enum { dimension = 4 };
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/// Default Constructor
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Event() : time_(0), location_(0, 0, 0) {}
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/// Constructor from time and location
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Event(double t, const Point3& p) : time_(t), location_(p) {}
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/// Constructor with doubles
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Event(double t, double x, double y, double z)
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: time_(t), location_(x, y, z) {}
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double time() const { return time_; }
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Point3 location() const { return location_; }
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// TODO(frank) we really have to think of a better way to do linear arguments
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double height(OptionalJacobian<1, 4> H = {}) const {
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static const Matrix14 JacobianZ = (Matrix14() << 0, 0, 0, 1).finished();
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if (H) *H = JacobianZ;
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return location_.z();
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}
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/** print with optional string */
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void print(const std::string& s = "") const;
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/** equals with an tolerance */
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bool equals(const Event& other,
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double tol = 1e-9) const;
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/// Updates a with tangent space delta
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inline Event retract(const Vector4& v) const {
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return Event(time_ + v[0], location_ + Point3(v.tail<3>()));
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}
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/// Returns inverse retraction
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inline Vector4 localCoordinates(const Event& q) const {
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return Vector4::Zero(); // TODO(frank) implement!
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}
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};
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// Define GTSAM traits
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template <>
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struct traits<Event> : internal::Manifold<Event> {};
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/// Time of arrival to given sensor
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class TimeOfArrival {
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const double speed_; ///< signal speed
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public:
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typedef double result_type;
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/// Constructor with optional speed of signal, in m/sec
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explicit TimeOfArrival(double speed = 330) : speed_(speed) {}
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/// Calculate time of arrival
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double measure(const Event& event, const Point3& sensor) const {
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double distance = gtsam::distance3(event.location(), sensor);
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return event.time() + distance / speed_;
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}
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/// Calculate time of arrival, with derivatives
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double operator()(const Event& event, const Point3& sensor, //
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OptionalJacobian<1, 4> H1 = {}, //
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OptionalJacobian<1, 3> H2 = {}) const {
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Matrix13 D1, D2;
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double distance = gtsam::distance3(event.location(), sensor, D1, D2);
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if (H1)
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// derivative of toa with respect to event
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*H1 << 1.0, D1 / speed_;
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if (H2)
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// derivative of toa with respect to sensor location
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*H2 << D2 / speed_;
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return event.time() + distance / speed_;
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}
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};
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} // namespace gtsam
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