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bug: navigation suggests `pathCorrection=inf` on cylinderSurface
Issue
We might encounter a FPEDIV in the path correction of the cylinder surface. This could happen when we end up parallel to the cylinder.
https://github.com/acts-project/acts/blob/dc1a1d35f97d60d90a51ef3255501cf41b115bcd/Core/src/Surfaces/CylinderSurface.cpp#L164
Stacktrace
15:26:16 Sequencer INFO -----------------------------------
15:26:16 Sequencer INFO FPE summary for Algorithm: TrackFittingAlgorithm
15:26:16 Sequencer INFO -----------------------------------
15:26:16 Sequencer INFO - FLTDIV: (3 times)
0# Acts::CylinderSurface::pathCorrection(Acts::ContextType const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&) const at /builds/acts/ci-bridge/src/Core/src/Surfaces/CylinderSurface.cpp:174
1# Acts::Layer::compatibleSurfaces(Acts::ContextType const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&, Acts::NavigationOptions<Acts::Surface> const&) const at /builds/acts/ci-bridge/src/Core/src/Geometry/Layer.cpp:151
2# bool Acts::Navigator::resolveSurfaces<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> >, Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer> >(Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> >&, Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer> const&) const [clone .isra.0] at /builds/acts/ci-bridge/src/Core/include/Acts/Propagator/Navigator.hpp:1055
3# void Acts::Navigator::preStep<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> >, Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer> >(Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> >&, Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer> const&) const at /builds/acts/ci-bridge/src/Core/include/Acts/Propagator/Navigator.hpp:356
4# Acts::Result<void, std::error_code> Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::propagate<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> > >(Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>::State<Acts::PropagatorOptions<Acts::ActionList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Actor<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> > >, Acts::AbortList<Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::Aborter<Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> >, Acts::PathLimitReached> >, Acts::Experimental::Gx2FitterResult<Acts::VectorMultiTrajectory> >&) const at /builds/acts/ci-bridge/src/Core/include/Acts/Propagator/Propagator.ipp:48
5# std::enable_if<!(false), Acts::Result<Acts::TrackContainer<Acts::VectorTrackContainer, Acts::VectorMultiTrajectory, std::shared_ptr>::TrackProxy, std::error_code> >::type Acts::Experimental::Gx2Fitter<Acts::Propagator<Acts::EigenStepper<Acts::StepperExtensionList<Acts::DefaultExtension>, Acts::detail::VoidAuctioneer>, Acts::Navigator>, Acts::VectorMultiTrajectory>::fit<__gnu_cxx::__normal_iterator<Acts::SourceLink const*, std::vector<Acts::SourceLink, std::allocator<Acts::SourceLink> > >, Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis>, Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis>, Acts::VectorTrackContainer, std::shared_ptr, false>(__gnu_cxx::__normal_iterator<Acts::SourceLink const*, std::vector<Acts::SourceLink, std::allocator<Acts::SourceLink> > >, __gnu_cxx::__normal_iterator<Acts::SourceLink const*, std::vector<Acts::SourceLink, std::allocator<Acts::SourceLink> > >, Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> const&, Acts::Experimental::Gx2FitterOptions<Acts::VectorMultiTrajectory> const&, Acts::TrackContainer<Acts::VectorTrackContainer, Acts::VectorMultiTrajectory, std::shared_ptr>&) const at /builds/acts/ci-bridge/src/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp:789
6# (anonymous namespace)::GlobalChiSquareFitterFunctionImpl::operator()(std::vector<Acts::SourceLink, std::allocator<Acts::SourceLink> > const&, Acts::GenericBoundTrackParameters<Acts::ParticleHypothesis> const&, ActsExamples::TrackFitterFunction::GeneralFitterOptions const&, ActsExamples::MeasurementCalibratorAdapter const&, Acts::TrackContainer<Acts::VectorTrackContainer, Acts::VectorMultiTrajectory, std::shared_ptr>&) const at /builds/acts/ci-bridge/src/Examples/Algorithms/TrackFitting/src/GlobalChiSquareFitterFunction.cpp:110
7# ActsExamples::TrackFittingAlgorithm::execute(ActsExamples::AlgorithmContext const&) const at /builds/acts/ci-bridge/src/Examples/Algorithms/TrackFitting/src/TrackFittingAlgorithm.cpp:148
Reproduce
Running truth_tracking_gx2f.py with 2.5 < |eta| < 3.0 can result in the above behaviour. When it happens, the gx2f pushed the updated parameters so far, that the first encountered surface is Pixels::Barrel instead of BeamPipe::Barrel:
oldChi2sum = 153.944
chi2sum = 1184.32
13:26:57 Gx2fFitter DEBUG chi2 not converging monotonically
13:26:57 Gx2fFitter VERBOSE nUpdate = 4/17
13:26:57 Gx2fFitter VERBOSE updated params:
loc0: -31.48 +- 1 1.000
loc1: 10.62 +- 1 0.000 1.000
phi: -2.856 +- 0.01745 0.000 0.000 1.000
theta: 0.1068 +- 0.01745 0.000 0.000 0.000 1.000
q/p: 0.1268 +- 0.1 0.000 0.000 0.000 0.000 1.000
time: -239.7 +- 299.8 0.000 0.000 0.000 0.000 0.000 1.000
on surface undefined of type Acts::PerigeeSurface
13:26:57 Gx2fNavigato VERBOSE No Volume | Initialization.
13:26:57 Gx2fNavigato VERBOSE No Volume | Current surface set to start surface undefined
13:26:57 Gx2fNavigato VERBOSE No Volume | Slow start initialization through search.
13:26:57 Gx2fNavigato VERBOSE No Volume | Starting from position (-8.8604, 30.2046, 10.6162) and direction (-0.1023, -0.0300, 0.9943)
13:26:57 Gx2fNavigato VERBOSE No Volume | Start volume resolved.
13:26:57 Gx2fPropagat VERBOSE Path aborter limit set to 41316.4 (full helix = 82632.8, previous limit = 1.79769e+308)
13:26:57 Gx2fPropagat VERBOSE Entering propagation.
13:26:57 Gx2fFitterAc VERBOSE Surface undefined detected.
13:26:57 Gx2fFitterAc INFO Actor: This case is not implemented yet
13:26:57 Gx2fFitterAc DEBUG result.processedMeasurements: 0
inputMeasurements.size()13
13:26:57 Gx2fPropagat VERBOSE PathLimit aborter | Target stepSize (path limit) updated to ( +∞, +∞, 41316.4, +∞)
13:26:57 Gx2fPropagat VERBOSE Starting stepping loop.
13:26:57 Gx2fNavigato VERBOSE Pixels::Barrel | Entering navigator::preStep.
13:26:57 Gx2fNavigato VERBOSE Pixels::Barrel | Start layer to be resolved.
cosAlpha: 0
However, we can also find sometimes values, that are just close to zero:
oldChi2sum = 1184.32
chi2sum = 4.08138
13:26:57 Gx2fFitter VERBOSE nUpdate = 5/17
13:26:57 Gx2fFitter VERBOSE updated params:
loc0: -31.08 +- 1 1.000
loc1: 9.863 +- 1 0.000 1.000
phi: -2.859 +- 0.01745 0.000 0.000 1.000
theta: 0.1068 +- 0.01745 0.000 0.000 0.000 1.000
q/p: 0.1254 +- 0.1 0.000 0.000 0.000 0.000 1.000
time: -239.7 +- 299.8 0.000 0.000 0.000 0.000 0.000 1.000
on surface undefined of type Acts::PerigeeSurface
13:26:57 Gx2fNavigato VERBOSE No Volume | Initialization.
13:26:57 Gx2fNavigato VERBOSE No Volume | Current surface set to start surface undefined
13:26:57 Gx2fNavigato VERBOSE No Volume | Slow start initialization through search.
13:26:57 Gx2fNavigato VERBOSE No Volume | Starting from position (-8.6749, 29.8417, 9.8631) and direction (-0.1024, -0.0298, 0.9943)
13:26:57 Gx2fNavigato VERBOSE No Volume | Start volume resolved.
13:26:57 Gx2fPropagat VERBOSE Path aborter limit set to 41791.9 (full helix = 83583.9, previous limit = 1.79769e+308)
13:26:57 Gx2fPropagat VERBOSE Entering propagation.
13:26:57 Gx2fFitterAc VERBOSE Surface undefined detected.
13:26:57 Gx2fFitterAc INFO Actor: This case is not implemented yet
13:26:57 Gx2fFitterAc DEBUG result.processedMeasurements: 0
inputMeasurements.size()13
13:26:57 Gx2fPropagat VERBOSE PathLimit aborter | Target stepSize (path limit) updated to ( +∞, +∞, 41791.9, +∞)
13:26:57 Gx2fPropagat VERBOSE Starting stepping loop.
13:26:57 Gx2fNavigato VERBOSE Pixels::Barrel | Entering navigator::preStep.
13:26:57 Gx2fNavigato VERBOSE Pixels::Barrel | Start layer to be resolved.
cosAlpha: 3.46945e-18
Solution
There have been a few attempts to solve this issue:
- https://github.com/acts-project/acts/pull/3254
- https://github.com/acts-project/acts/pull/3255
In the end, we decided not to treat the symptoms, but rather find the underlying issue.
Since it only occurred for the GX2F, this issue might solve itself during further development. However, I don't see it as the GX2F's responsible to check if the navigation will work with newly suggested parameters.
13:26:57 Gx2fFitter VERBOSE updated params:
loc0: -31.48 +- 1 1.000
loc1: 10.62 +- 1 0.000 1.000
phi: -2.856 +- 0.01745 0.000 0.000 1.000
theta: 0.1068 +- 0.01745 0.000 0.000 0.000 1.000
q/p: 0.1268 +- 0.1 0.000 0.000 0.000 0.000 1.000
time: -239.7 +- 299.8 0.000 0.000 0.000 0.000 0.000 1.000
This suggests that the fitter is unstable for certain inputs / scenarios. I would argue that the navigation is supposed to break in this scenario.
Note that eta for these parameters is almost 3 which is at the edge of what the ODD can handle usually.
I also quickly checked the input vectors and they are practically orthogonal in XY.
In [8]: p = np.array([-8.8604, 30.2046, 10.6162])
In [9]: p[:2] / np.linalg.norm(p[:2])
Out[9]: array([-0.2814848 , 0.95956569])
In [10]: d = np.array([-0.1023, -0.0300, 0.9943])
In [11]: d[:2] / np.linalg.norm(d[:2])
Out[11]: array([-0.95958925, -0.28140447])
All in all I would argue that this is not a bug of the navigation but a bug of the fitter as the start parameters for the propagation are unphysical for what it is trying to fit.
This issue/PR has been automatically marked as stale because it has not had recent activity. The stale label will be removed if any interaction occurs.
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#3411 does not solve the underlying issue but rather avoids getting there in the first place. I would keep it open for now.
This issue/PR has been automatically marked as stale because it has not had recent activity. The stale label will be removed if any interaction occurs.
This issue/PR has been automatically marked as stale because it has not had recent activity. The stale label will be removed if any interaction occurs.
This issue/PR has been automatically marked as stale because it has not had recent activity. The stale label will be removed if any interaction occurs.