refactor!: Remove smoothing and extrapolation from core CKF

[andiwand]

After #2539 I want to finally refactor the CKF and remove the smoothing and the reference surface targeting from the core algorithm in order to make it more composable and less complicated.

Before the CKF was basically only usable with smoothing turned on otherwise we would not receive any tracks. Now it always runs without smoothing and the user can decide what and how to smooth. Afterwards the user can decide which track state they want to extrapolate to a reference surface if necessary.

IMO this makes the algorithm flow much easier to comprehend and gives the user more flexibility. This also makes an implementation of a two way finding easier as discovered in #2717

blocked by

• refactor: Make MaterialInteractor noise mode independent from direction #2723

---

Users can smooth and extrapolate tracks after the CKF returns them. Extrapolation can be achieved using the Propagator while smoothing can be done by the GainMatrixSmoother.

For convenience this PR also includes helper functions to smooth and extrapolate single tracks or a whole track container.

Example of smoothing and extrapolating tracks after the CKF

acts/Examples/Algorithms/TrackFinding/src/TrackFindingAlgorithm.cpp

Lines 172 to 189 in 9818689

	auto smoothingResult =
	Acts::smoothTrack(ctx.geoContext, tracksTemp, track, logger());
	if (!smoothingResult.ok()) {
	ACTS_ERROR("Smoothing for seed "
	<< iseed << " and track " << track.index()
	<< " failed with error " << smoothingResult.error());
	continue;
	}
	auto extrapolationResult = Acts::extrapolateTrackToReferenceSurface(
	track, *pSurface, extrapolator, extrapolationOptions,
	m_cfg.extrapolationStrategy, logger());
	if (!extrapolationResult.ok()) {
	ACTS_ERROR("Extrapolation for seed "
	<< iseed << " and track " << track.index()
	<< " failed with error " << extrapolationResult.error());
	continue;
	}

[codecov]

Codecov Report

Attention: Patch coverage is 9.67742% with 28 lines in your changes are missing coverage. Please review.

Project coverage is 49.01%. Comparing base (9e72306) to head (8e11c91).

Files	Patch %	Lines
...de/Acts/TrackFinding/CombinatorialKalmanFilter.hpp	15.00%	12 Missing and 5 partials ⚠️
Core/src/Utilities/TrackHelpers.cpp	0.00%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2722      +/-   ##
==========================================
+ Coverage   48.99%   49.01%   +0.02%     
==========================================
  Files         490      491       +1     
  Lines       28996    28886     -110     
  Branches    13743    13685      -58     
==========================================
- Hits        14206    14159      -47     
+ Misses       4951     4938      -13     
+ Partials     9839     9789      -50     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

📊: Physics performance monitoring for 8e11c91

Full contents

physmon summary

• ✅ CKF truth_smeared
• ✅ IVF truth_smeared
• ✅ AMVF truth_smeared
• ✅ Track Summary CKF truth_smeared
• ✅ Seeding truth_estimated
• ✅ CKF truth_estimated
• ✅ IVF truth_estimated
• ✅ AMVF truth_estimated
• ✅ Track Summary CKF truth_estimated
• ✅ Seeding seeded
• ✅ CKF seeded
• ✅ IVF seeded
• ✅ AMVF seeded
• ✅ AMVF (+grid seeder) seeded
• ✅ Track Summary CKF seeded
• ✅ Seeding orthogonal
• ✅ CKF orthogonal
• ✅ IVF orthogonal
• ✅ AMVF orthogonal
• ✅ Track Summary CKF orthogonal
• ✅ Ambisolver seeded
• ✅ Ambisolver orthogonal
• ✅ Seeding ttbar
• ✅ CKF ttbar
• ✅ Ambisolver
• ✅ Track Summary CKF ttbar
• ✅ AMVF ttbar
• ✅ AMVF (+grid seeder) ttbar
• ✅ Truth tracking (GSF)
• ✅ Truth tracking
• ✅ Truth tracking (GX2F)
• ✅ Particles fatras
• ✅ Particles geant4

[AJPfleger]

Please add diff to description as discussed

[acts-project-service]

✅ Athena integration test results [d9f775f]

✅ All tests successful

status	job	report
🟢	run_unit_tests
🟢	test_ActsEFTrackFit
🟢	test_ActsPersistifySeeds
🟢	test_ActsBenchmarkWithSpot
🟢	test_ActsAnalogueClustering
🟢	test_ActsConversionWorkflow
🟢	test_ActsWorkflowFastTracking
🟢	test_ActsWorkflow
🟢	test_ActsValidateAmbiguityResolution
🟢	test_ActsValidateResolvedTracks
🟢	test_ActsValidateTracks
🟢	test_ActsValidateActsCoreSpacePoints
🟢	test_ActsValidateActsSpacePoints
🟢	test_ActsValidateSeeds
🟢	test_ActsValidateOrthogonalSeeds
🟢	test_ActsValidateClusters
🟢	test_ActsPersistifyEDM
🟢	test_ActsGSFRefitting
🟢	test_ActsKfRefitting
🟢	test_ActsExtrapolationAlgTest
🟢	test_ActsITkTest
🟢	run_workflow_tests_run4_mc
🟢	run_workflow_tests_run2_mc
🟢	run_workflow_tests_run2_data
🟢	run_workflow_tests_run3_mc
🟢	run_workflow_tests_run3_data
🟢	run_art_test: test_data18_13TeV_1000evt
🟢	run_art_test: test_ttbarPU40_reco

[paulgessinger]

Let's go!