gtsam/gtsam/geometry/triangulation.h

638 lines
24 KiB
C++

/* ----------------------------------------------------------------------------
* 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 triangulation.h
* @brief Functions for triangulation
* @date July 31, 2013
* @author Chris Beall
* @author Luca Carlone
*/
#pragma once
#include <gtsam/geometry/Cal3Bundler.h>
#include <gtsam/geometry/Cal3Fisheye.h>
#include <gtsam/geometry/Cal3Unified.h>
#include <gtsam/geometry/Cal3_S2.h>
#include <gtsam/geometry/Cal3DS2.h>
#include <gtsam/geometry/CameraSet.h>
#include <gtsam/geometry/PinholeCamera.h>
#include <gtsam/geometry/SphericalCamera.h>
#include <gtsam/geometry/Pose2.h>
#include <gtsam/inference/Symbol.h>
#include <gtsam/nonlinear/NonlinearFactorGraph.h>
#include <gtsam/slam/TriangulationFactor.h>
namespace gtsam {
/// Exception thrown by triangulateDLT when SVD returns rank < 3
class GTSAM_EXPORT TriangulationUnderconstrainedException: public std::runtime_error {
public:
TriangulationUnderconstrainedException() :
std::runtime_error("Triangulation Underconstrained Exception.") {
}
};
/// Exception thrown by triangulateDLT when landmark is behind one or more of the cameras
class GTSAM_EXPORT TriangulationCheiralityException: public std::runtime_error {
public:
TriangulationCheiralityException() :
std::runtime_error(
"Triangulation Cheirality Exception: The resulting landmark is behind one or more cameras.") {
}
};
/**
* DLT triangulation: See Hartley and Zisserman, 2nd Ed., page 312
* @param projection_matrices Projection matrices (K*P^-1)
* @param measurements 2D measurements
* @param rank_tol SVD rank tolerance
* @return Triangulated point, in homogeneous coordinates
*/
GTSAM_EXPORT Vector4 triangulateHomogeneousDLT(
const std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>>& projection_matrices,
const Point2Vector& measurements, double rank_tol = 1e-9);
/**
* Same math as Hartley and Zisserman, 2nd Ed., page 312, but with unit-norm bearing vectors
* (contrarily to pinhole projection, the z entry is not assumed to be 1 as in Hartley and Zisserman)
* @param projection_matrices Projection matrices (K*P^-1)
* @param measurements Unit3 bearing measurements
* @param rank_tol SVD rank tolerance
* @return Triangulated point, in homogeneous coordinates
*/
GTSAM_EXPORT Vector4 triangulateHomogeneousDLT(
const std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>>& projection_matrices,
const std::vector<Unit3>& measurements, double rank_tol = 1e-9);
/**
* DLT triangulation: See Hartley and Zisserman, 2nd Ed., page 312
* @param projection_matrices Projection matrices (K*P^-1)
* @param measurements 2D measurements
* @param rank_tol SVD rank tolerance
* @return Triangulated Point3
*/
GTSAM_EXPORT Point3 triangulateDLT(
const std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>>& projection_matrices,
const Point2Vector& measurements,
double rank_tol = 1e-9);
/**
* overload of previous function to work with Unit3 (projected to canonical camera)
*/
GTSAM_EXPORT Point3 triangulateDLT(
const std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>>& projection_matrices,
const std::vector<Unit3>& measurements,
double rank_tol = 1e-9);
/**
* Create a factor graph with projection factors from poses and one calibration
* @param poses Camera poses
* @param sharedCal shared pointer to single calibration object (monocular only!)
* @param measurements 2D measurements
* @param landmarkKey to refer to landmark
* @param initialEstimate
* @return graph and initial values
*/
template<class CALIBRATION>
std::pair<NonlinearFactorGraph, Values> triangulationGraph(
const std::vector<Pose3>& poses, boost::shared_ptr<CALIBRATION> sharedCal,
const Point2Vector& measurements, Key landmarkKey,
const Point3& initialEstimate,
const SharedNoiseModel& model = nullptr) {
Values values;
values.insert(landmarkKey, initialEstimate); // Initial landmark value
NonlinearFactorGraph graph;
static SharedNoiseModel unit2(noiseModel::Unit::Create(2));
for (size_t i = 0; i < measurements.size(); i++) {
const Pose3& pose_i = poses[i];
typedef PinholePose<CALIBRATION> Camera;
Camera camera_i(pose_i, sharedCal);
graph.emplace_shared<TriangulationFactor<Camera> > //
(camera_i, measurements[i], model? model : unit2, landmarkKey);
}
return std::make_pair(graph, values);
}
/**
* Create a factor graph with projection factors from pinhole cameras
* (each camera has a pose and calibration)
* @param cameras pinhole cameras (monocular or stereo)
* @param measurements 2D measurements
* @param landmarkKey to refer to landmark
* @param initialEstimate
* @return graph and initial values
*/
template<class CAMERA>
std::pair<NonlinearFactorGraph, Values> triangulationGraph(
const CameraSet<CAMERA>& cameras,
const typename CAMERA::MeasurementVector& measurements, Key landmarkKey,
const Point3& initialEstimate,
const SharedNoiseModel& model = nullptr) {
Values values;
values.insert(landmarkKey, initialEstimate); // Initial landmark value
NonlinearFactorGraph graph;
static SharedNoiseModel unit(noiseModel::Unit::Create(
traits<typename CAMERA::Measurement>::dimension));
for (size_t i = 0; i < measurements.size(); i++) {
const CAMERA& camera_i = cameras[i];
graph.emplace_shared<TriangulationFactor<CAMERA> > //
(camera_i, measurements[i], model? model : unit, landmarkKey);
}
return std::make_pair(graph, values);
}
/**
* Optimize for triangulation
* @param graph nonlinear factors for projection
* @param values initial values
* @param landmarkKey to refer to landmark
* @return refined Point3
*/
GTSAM_EXPORT Point3 optimize(const NonlinearFactorGraph& graph,
const Values& values, Key landmarkKey);
/**
* Given an initial estimate , refine a point using measurements in several cameras
* @param poses Camera poses
* @param sharedCal shared pointer to single calibration object
* @param measurements 2D measurements
* @param initialEstimate
* @return refined Point3
*/
template<class CALIBRATION>
Point3 triangulateNonlinear(const std::vector<Pose3>& poses,
boost::shared_ptr<CALIBRATION> sharedCal,
const Point2Vector& measurements, const Point3& initialEstimate,
const SharedNoiseModel& model = nullptr) {
// Create a factor graph and initial values
Values values;
NonlinearFactorGraph graph;
boost::tie(graph, values) = triangulationGraph<CALIBRATION> //
(poses, sharedCal, measurements, Symbol('p', 0), initialEstimate, model);
return optimize(graph, values, Symbol('p', 0));
}
/**
* Given an initial estimate , refine a point using measurements in several cameras
* @param cameras pinhole cameras (monocular or stereo)
* @param measurements 2D measurements
* @param initialEstimate
* @return refined Point3
*/
template<class CAMERA>
Point3 triangulateNonlinear(
const CameraSet<CAMERA>& cameras,
const typename CAMERA::MeasurementVector& measurements, const Point3& initialEstimate,
const SharedNoiseModel& model = nullptr) {
// Create a factor graph and initial values
Values values;
NonlinearFactorGraph graph;
boost::tie(graph, values) = triangulationGraph<CAMERA> //
(cameras, measurements, Symbol('p', 0), initialEstimate, model);
return optimize(graph, values, Symbol('p', 0));
}
template<class CAMERA>
std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>>
projectionMatricesFromCameras(const CameraSet<CAMERA> &cameras) {
std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>> projection_matrices;
for (const CAMERA &camera: cameras) {
projection_matrices.push_back(camera.cameraProjectionMatrix());
}
return projection_matrices;
}
// overload, assuming pinholePose
template<class CALIBRATION>
std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>> projectionMatricesFromPoses(
const std::vector<Pose3> &poses, boost::shared_ptr<CALIBRATION> sharedCal) {
std::vector<Matrix34, Eigen::aligned_allocator<Matrix34>> projection_matrices;
for (size_t i = 0; i < poses.size(); i++) {
PinholePose<CALIBRATION> camera(poses.at(i), sharedCal);
projection_matrices.push_back(camera.cameraProjectionMatrix());
}
return projection_matrices;
}
/** Create a pinhole calibration from a different Cal3 object, removing
* distortion.
*
* @tparam CALIBRATION Original calibration object.
* @param cal Input calibration object.
* @return Cal3_S2 with only the pinhole elements of cal.
*/
template <class CALIBRATION>
Cal3_S2 createPinholeCalibration(const CALIBRATION& cal) {
const auto& K = cal.K();
return Cal3_S2(K(0, 0), K(1, 1), K(0, 1), K(0, 2), K(1, 2));
}
/** Internal undistortMeasurement to be used by undistortMeasurement and
* undistortMeasurements */
template <class CALIBRATION, class MEASUREMENT>
MEASUREMENT undistortMeasurementInternal(
const CALIBRATION& cal, const MEASUREMENT& measurement,
boost::optional<Cal3_S2> pinholeCal = boost::none) {
if (!pinholeCal) {
pinholeCal = createPinholeCalibration(cal);
}
return pinholeCal->uncalibrate(cal.calibrate(measurement));
}
/** Remove distortion for measurements so as if the measurements came from a
* pinhole camera.
*
* Removes distortion but maintains the K matrix of the initial cal. Operates by
* calibrating using full calibration and uncalibrating with only the pinhole
* component of the calibration.
* @tparam CALIBRATION Calibration type to use.
* @param cal Calibration with which measurements were taken.
* @param measurements Vector of measurements to undistort.
* @return measurements with the effect of the distortion of sharedCal removed.
*/
template <class CALIBRATION>
Point2Vector undistortMeasurements(const CALIBRATION& cal,
const Point2Vector& measurements) {
Cal3_S2 pinholeCalibration = createPinholeCalibration(cal);
Point2Vector undistortedMeasurements;
// Calibrate with cal and uncalibrate with pinhole version of cal so that
// measurements are undistorted.
std::transform(measurements.begin(), measurements.end(),
std::back_inserter(undistortedMeasurements),
[&cal, &pinholeCalibration](const Point2& measurement) {
return undistortMeasurementInternal<CALIBRATION>(
cal, measurement, pinholeCalibration);
});
return undistortedMeasurements;
}
/** Specialization for Cal3_S2 as it doesn't need to be undistorted. */
template <>
inline Point2Vector undistortMeasurements(const Cal3_S2& cal,
const Point2Vector& measurements) {
return measurements;
}
/** Remove distortion for measurements so as if the measurements came from a
* pinhole camera.
*
* Removes distortion but maintains the K matrix of the initial calibrations.
* Operates by calibrating using full calibration and uncalibrating with only
* the pinhole component of the calibration.
* @tparam CAMERA Camera type to use.
* @param cameras Cameras corresponding to each measurement.
* @param measurements Vector of measurements to undistort.
* @return measurements with the effect of the distortion of the camera removed.
*/
template <class CAMERA>
typename CAMERA::MeasurementVector undistortMeasurements(
const CameraSet<CAMERA>& cameras,
const typename CAMERA::MeasurementVector& measurements) {
const size_t num_meas = cameras.size();
assert(num_meas == measurements.size());
typename CAMERA::MeasurementVector undistortedMeasurements(num_meas);
for (size_t ii = 0; ii < num_meas; ++ii) {
// Calibrate with cal and uncalibrate with pinhole version of cal so that
// measurements are undistorted.
undistortedMeasurements[ii] =
undistortMeasurementInternal<typename CAMERA::CalibrationType>(
cameras[ii].calibration(), measurements[ii]);
}
return undistortedMeasurements;
}
/** Specialize for Cal3_S2 to do nothing. */
template <class CAMERA = PinholeCamera<Cal3_S2>>
inline PinholeCamera<Cal3_S2>::MeasurementVector undistortMeasurements(
const CameraSet<PinholeCamera<Cal3_S2>>& cameras,
const PinholeCamera<Cal3_S2>::MeasurementVector& measurements) {
return measurements;
}
/** Specialize for SphericalCamera to do nothing. */
template <class CAMERA = SphericalCamera>
inline SphericalCamera::MeasurementVector undistortMeasurements(
const CameraSet<SphericalCamera>& cameras,
const SphericalCamera::MeasurementVector& measurements) {
return measurements;
}
/**
* Function to triangulate 3D landmark point from an arbitrary number
* of poses (at least 2) using the DLT. The function checks that the
* resulting point lies in front of all cameras, but has no other checks
* to verify the quality of the triangulation.
* @param poses A vector of camera poses
* @param sharedCal shared pointer to single calibration object
* @param measurements A vector of camera measurements
* @param rank_tol rank tolerance, default 1e-9
* @param optimize Flag to turn on nonlinear refinement of triangulation
* @return Returns a Point3
*/
template<class CALIBRATION>
Point3 triangulatePoint3(const std::vector<Pose3>& poses,
boost::shared_ptr<CALIBRATION> sharedCal,
const Point2Vector& measurements, double rank_tol = 1e-9,
bool optimize = false,
const SharedNoiseModel& model = nullptr) {
assert(poses.size() == measurements.size());
if (poses.size() < 2)
throw(TriangulationUnderconstrainedException());
// construct projection matrices from poses & calibration
auto projection_matrices = projectionMatricesFromPoses(poses, sharedCal);
// Undistort the measurements, leaving only the pinhole elements in effect.
auto undistortedMeasurements =
undistortMeasurements<CALIBRATION>(*sharedCal, measurements);
// Triangulate linearly
Point3 point =
triangulateDLT(projection_matrices, undistortedMeasurements, rank_tol);
// Then refine using non-linear optimization
if (optimize)
point = triangulateNonlinear<CALIBRATION> //
(poses, sharedCal, measurements, point, model);
#ifdef GTSAM_THROW_CHEIRALITY_EXCEPTION
// verify that the triangulated point lies in front of all cameras
for(const Pose3& pose: poses) {
const Point3& p_local = pose.transformTo(point);
if (p_local.z() <= 0)
throw(TriangulationCheiralityException());
}
#endif
return point;
}
/**
* Function to triangulate 3D landmark point from an arbitrary number
* of poses (at least 2) using the DLT. This function is similar to the one
* above, except that each camera has its own calibration. The function
* checks that the resulting point lies in front of all cameras, but has
* no other checks to verify the quality of the triangulation.
* @param cameras pinhole cameras
* @param measurements A vector of camera measurements
* @param rank_tol rank tolerance, default 1e-9
* @param optimize Flag to turn on nonlinear refinement of triangulation
* @return Returns a Point3
*/
template<class CAMERA>
Point3 triangulatePoint3(
const CameraSet<CAMERA>& cameras,
const typename CAMERA::MeasurementVector& measurements, double rank_tol = 1e-9,
bool optimize = false,
const SharedNoiseModel& model = nullptr) {
size_t m = cameras.size();
assert(measurements.size() == m);
if (m < 2)
throw(TriangulationUnderconstrainedException());
// construct projection matrices from poses & calibration
auto projection_matrices = projectionMatricesFromCameras(cameras);
// Undistort the measurements, leaving only the pinhole elements in effect.
auto undistortedMeasurements =
undistortMeasurements<CAMERA>(cameras, measurements);
Point3 point =
triangulateDLT(projection_matrices, undistortedMeasurements, rank_tol);
// The n refine using non-linear optimization
if (optimize)
point = triangulateNonlinear<CAMERA>(cameras, measurements, point, model);
#ifdef GTSAM_THROW_CHEIRALITY_EXCEPTION
// verify that the triangulated point lies in front of all cameras
for(const CAMERA& camera: cameras) {
const Point3& p_local = camera.pose().transformTo(point);
if (p_local.z() <= 0)
throw(TriangulationCheiralityException());
}
#endif
return point;
}
/// Pinhole-specific version
template<class CALIBRATION>
Point3 triangulatePoint3(
const CameraSet<PinholeCamera<CALIBRATION> >& cameras,
const Point2Vector& measurements, double rank_tol = 1e-9,
bool optimize = false,
const SharedNoiseModel& model = nullptr) {
return triangulatePoint3<PinholeCamera<CALIBRATION> > //
(cameras, measurements, rank_tol, optimize, model);
}
struct GTSAM_EXPORT TriangulationParameters {
double rankTolerance; ///< threshold to decide whether triangulation is result.degenerate
///< (the rank is the number of singular values of the triangulation matrix which are larger than rankTolerance)
bool enableEPI; ///< if set to true, will refine triangulation using LM
/**
* if the landmark is triangulated at distance larger than this,
* result is flagged as degenerate.
*/
double landmarkDistanceThreshold; //
/**
* If this is nonnegative the we will check if the average reprojection error
* is smaller than this threshold after triangulation, otherwise result is
* flagged as degenerate.
*/
double dynamicOutlierRejectionThreshold;
SharedNoiseModel noiseModel; ///< used in the nonlinear triangulation
/**
* Constructor
* @param rankTol tolerance used to check if point triangulation is degenerate
* @param enableEPI if true refine triangulation with embedded LM iterations
* @param landmarkDistanceThreshold flag as degenerate if point further than this
* @param dynamicOutlierRejectionThreshold or if average error larger than this
* @param noiseModel noise model to use during nonlinear triangulation
*
*/
TriangulationParameters(const double _rankTolerance = 1.0,
const bool _enableEPI = false, double _landmarkDistanceThreshold = -1,
double _dynamicOutlierRejectionThreshold = -1,
const SharedNoiseModel& _noiseModel = nullptr) :
rankTolerance(_rankTolerance), enableEPI(_enableEPI), //
landmarkDistanceThreshold(_landmarkDistanceThreshold), //
dynamicOutlierRejectionThreshold(_dynamicOutlierRejectionThreshold),
noiseModel(_noiseModel){
}
// stream to output
friend std::ostream &operator<<(std::ostream &os,
const TriangulationParameters& p) {
os << "rankTolerance = " << p.rankTolerance << std::endl;
os << "enableEPI = " << p.enableEPI << std::endl;
os << "landmarkDistanceThreshold = " << p.landmarkDistanceThreshold
<< std::endl;
os << "dynamicOutlierRejectionThreshold = "
<< p.dynamicOutlierRejectionThreshold << std::endl;
os << "noise model" << std::endl;
return os;
}
private:
/// Serialization function
friend class boost::serialization::access;
template<class ARCHIVE>
void serialize(ARCHIVE & ar, const unsigned int version) {
ar & BOOST_SERIALIZATION_NVP(rankTolerance);
ar & BOOST_SERIALIZATION_NVP(enableEPI);
ar & BOOST_SERIALIZATION_NVP(landmarkDistanceThreshold);
ar & BOOST_SERIALIZATION_NVP(dynamicOutlierRejectionThreshold);
}
};
/**
* TriangulationResult is an optional point, along with the reasons why it is
* invalid.
*/
class TriangulationResult : public boost::optional<Point3> {
public:
enum Status { VALID, DEGENERATE, BEHIND_CAMERA, OUTLIER, FAR_POINT };
Status status;
private:
TriangulationResult(Status s) : status(s) {}
public:
/**
* Default constructor, only for serialization
*/
TriangulationResult() {}
/**
* Constructor
*/
TriangulationResult(const Point3& p) : status(VALID) { reset(p); }
static TriangulationResult Degenerate() {
return TriangulationResult(DEGENERATE);
}
static TriangulationResult Outlier() { return TriangulationResult(OUTLIER); }
static TriangulationResult FarPoint() {
return TriangulationResult(FAR_POINT);
}
static TriangulationResult BehindCamera() {
return TriangulationResult(BEHIND_CAMERA);
}
bool valid() const { return status == VALID; }
bool degenerate() const { return status == DEGENERATE; }
bool outlier() const { return status == OUTLIER; }
bool farPoint() const { return status == FAR_POINT; }
bool behindCamera() const { return status == BEHIND_CAMERA; }
// stream to output
friend std::ostream& operator<<(std::ostream& os,
const TriangulationResult& result) {
if (result)
os << "point = " << *result << std::endl;
else
os << "no point, status = " << result.status << std::endl;
return os;
}
private:
/// Serialization function
friend class boost::serialization::access;
template <class ARCHIVE>
void serialize(ARCHIVE& ar, const unsigned int version) {
ar& BOOST_SERIALIZATION_NVP(status);
}
};
/// triangulateSafe: extensive checking of the outcome
template<class CAMERA>
TriangulationResult triangulateSafe(const CameraSet<CAMERA>& cameras,
const typename CAMERA::MeasurementVector& measured,
const TriangulationParameters& params) {
size_t m = cameras.size();
// if we have a single pose the corresponding factor is uninformative
if (m < 2)
return TriangulationResult::Degenerate();
else
// We triangulate the 3D position of the landmark
try {
Point3 point =
triangulatePoint3<CAMERA>(cameras, measured, params.rankTolerance,
params.enableEPI, params.noiseModel);
// Check landmark distance and re-projection errors to avoid outliers
size_t i = 0;
double maxReprojError = 0.0;
for(const CAMERA& camera: cameras) {
const Pose3& pose = camera.pose();
if (params.landmarkDistanceThreshold > 0
&& distance3(pose.translation(), point)
> params.landmarkDistanceThreshold)
return TriangulationResult::FarPoint();
#ifdef GTSAM_THROW_CHEIRALITY_EXCEPTION
// verify that the triangulated point lies in front of all cameras
// Only needed if this was not yet handled by exception
const Point3& p_local = pose.transformTo(point);
if (p_local.z() <= 0)
return TriangulationResult::BehindCamera();
#endif
// Check reprojection error
if (params.dynamicOutlierRejectionThreshold > 0) {
const typename CAMERA::Measurement& zi = measured.at(i);
Point2 reprojectionError = camera.reprojectionError(point, zi);
maxReprojError = std::max(maxReprojError, reprojectionError.norm());
}
i += 1;
}
// Flag as degenerate if average reprojection error is too large
if (params.dynamicOutlierRejectionThreshold > 0
&& maxReprojError > params.dynamicOutlierRejectionThreshold)
return TriangulationResult::Outlier();
// all good!
return TriangulationResult(point);
} catch (TriangulationUnderconstrainedException&) {
// This exception is thrown if
// 1) There is a single pose for triangulation - this should not happen because we checked the number of poses before
// 2) The rank of the matrix used for triangulation is < 3: rotation-only, parallel cameras (or motion towards the landmark)
return TriangulationResult::Degenerate();
} catch (TriangulationCheiralityException&) {
// point is behind one of the cameras: can be the case of close-to-parallel cameras or may depend on outliers
return TriangulationResult::BehindCamera();
}
}
// Vector of Cameras - used by the Python/MATLAB wrapper
using CameraSetCal3Bundler = CameraSet<PinholeCamera<Cal3Bundler>>;
using CameraSetCal3_S2 = CameraSet<PinholeCamera<Cal3_S2>>;
using CameraSetCal3DS2 = CameraSet<PinholeCamera<Cal3DS2>>;
using CameraSetCal3Fisheye = CameraSet<PinholeCamera<Cal3Fisheye>>;
using CameraSetCal3Unified = CameraSet<PinholeCamera<Cal3Unified>>;
using CameraSetSpherical = CameraSet<SphericalCamera>;
} // \namespace gtsam