fix: kf+gsf: correct hole-tagging for edge case

Core/include/Acts/TrackFitting/KalmanFitter.hpp

@@ -582,8 +582,13 @@ class KalmanFitter {
     Result<void> filter(const Surface* surface, propagator_state_t& state,
                         const stepper_t& stepper, const navigator_t& navigator,
                         result_type& result) const {
+      const bool precedingMeasurementExists = (result.measurementStates > 0);
+      const bool surfaceIsSensitive =
+          (surface->associatedDetectorElement() != nullptr);
+      const bool surfaceHasMaterial = (surface->surfaceMaterial() != nullptr);
+      const auto sourcelink_it = inputMeasurements->find(surface->geometryId());
+
       // Try to find the surface in the measurement surfaces
-      auto sourcelink_it = inputMeasurements->find(surface->geometryId());
       if (sourcelink_it != inputMeasurements->end()) {
         // Screen output message
         ACTS_VERBOSE("Measurement surface " << surface->geometryId()
@@ -638,32 +643,31 @@ class KalmanFitter {
         // the lastTrackIndex.
         result.lastMeasurementIndex = result.lastTrackIndex;
 
-      } else if (surface->associatedDetectorElement() != nullptr ||
-                 surface->surfaceMaterial() != nullptr) {
+      } else if ((precedingMeasurementExists && surfaceIsSensitive) ||
+                 surfaceHasMaterial) {
         // We only create track states here if there is already measurement
         // detected or if the surface has material (no holes before the first
         // measurement)
-        if (result.measurementStates > 0 ||
-            surface->surfaceMaterial() != nullptr) {
-          auto trackStateProxyRes = detail::kalmanHandleNoMeasurement(
-              state, stepper, *surface, *result.fittedStates,
-              result.lastTrackIndex, true, logger(), freeToBoundCorrection);
-
-          if (!trackStateProxyRes.ok()) {
-            return trackStateProxyRes.error();
-          }
+        auto trackStateProxyRes = detail::kalmanHandleNoMeasurement(
+            state, stepper, *surface, *result.fittedStates,
+            result.lastTrackIndex, true, logger(), precedingMeasurementExists,
+            freeToBoundCorrection);
 
-          const auto& trackStateProxy = *trackStateProxyRes;
-          result.lastTrackIndex = trackStateProxy.index();
+        if (!trackStateProxyRes.ok()) {
+          return trackStateProxyRes.error();
+        }
 
-          if (trackStateProxy.typeFlags().test(TrackStateFlag::HoleFlag)) {
-            // Count the missed surface
-            result.missedActiveSurfaces.push_back(surface);
-          }
+        const auto& trackStateProxy = *trackStateProxyRes;
+        result.lastTrackIndex = trackStateProxy.index();
 
-          ++result.processedStates;
+        if (trackStateProxy.typeFlags().test(TrackStateFlag::HoleFlag)) {
+          // Count the missed surface
+          result.missedActiveSurfaces.push_back(surface);
         }
-        if (surface->surfaceMaterial() != nullptr) {
+
+        ++result.processedStates;
+
+        if (surfaceHasMaterial) {
           // Update state and stepper with material effects
           materialInteractor(surface, state, stepper, navigator,
                              MaterialUpdateStage::FullUpdate);

Core/include/Acts/TrackFitting/detail/GsfActor.hpp

@@ -634,6 +634,8 @@ struct GsfActor {
                                    bool doCovTransport) const {
     const auto& surface = *navigator.currentSurface(state.navigation);
 
+    const bool precedingMeasurementExists = result.processedStates > 0;
+
     // Initialize as true, so that any component can flip it. However, all
     // components should behave the same
     bool is_hole = true;
@@ -647,7 +649,8 @@ struct GsfActor {
       // now until we measure this is significant
       auto trackStateProxyRes = detail::kalmanHandleNoMeasurement(
           singleState, singleStepper, surface, tmpStates.traj,
-          MultiTrajectoryTraits::kInvalid, doCovTransport, logger());
+          MultiTrajectoryTraits::kInvalid, doCovTransport, logger(),
+          precedingMeasurementExists);
 
       if (!trackStateProxyRes.ok()) {
         return trackStateProxyRes.error();

Core/include/Acts/TrackFitting/detail/KalmanUpdateHelpers.hpp

@@ -135,7 +135,7 @@ template <typename propagator_state_t, typename stepper_t, typename traj_t>
 auto kalmanHandleNoMeasurement(
     propagator_state_t &state, const stepper_t &stepper, const Surface &surface,
     traj_t &fittedStates, const std::size_t lastTrackIndex, bool doCovTransport,
-    const Logger &logger,
+    const Logger &logger, const bool precedingMeasurementExists,
     const FreeToBoundCorrection &freeToBoundCorrection = FreeToBoundCorrection(
         false)) -> Result<typename traj_t::TrackStateProxy> {
   // Add a <mask> TrackState entry multi trajectory. This allocates storage for
@@ -177,10 +177,14 @@ auto kalmanHandleNoMeasurement(
   if (surface.surfaceMaterial() != nullptr) {
     typeFlags.set(TrackStateFlag::MaterialFlag);
   }
-  if (surface.associatedDetectorElement() != nullptr) {
+  if (surface.associatedDetectorElement() != nullptr &&
+      precedingMeasurementExists) {
     ACTS_VERBOSE("Detected hole on " << surface.geometryId());
     // If the surface is sensitive, set the hole type flag
     typeFlags.set(TrackStateFlag::HoleFlag);
+  } else if (surface.associatedDetectorElement() != nullptr) {
+    ACTS_VERBOSE("Skip hole (no preceding measurements) on surface "
+                 << surface.geometryId());
   } else if (surface.surfaceMaterial() != nullptr) {
     ACTS_VERBOSE("Detected in-sensitive surface " << surface.geometryId());
   }

Examples/Python/tests/root_file_hashes.txt

@@ -77,15 +77,15 @@ test_ML_Ambiguity_Solver__performance_ambiML.root: 284ff5c3a08c0b810938e4ac2f8ba
 test_refitting[odd]__trackstates_gsf_refit.root: 33de1e46b05abc450ff89aebc728d7cb85e3f4dc90e5a21fc79a1ed8e9e04d7d
 test_refitting[odd]__tracksummary_gsf_refit.root: 16951808df6363d2acb99e385aec35ad723b634403ca0724a552ae9d3a2ae237
 test_refitting[generic]__trackstates_gsf_refit.root: ae07a875975a416d323d98b4b16dd3edc5ae672a8993ecb624758a770afdffbd
-test_refitting[generic]__tracksummary_gsf_refit.root: bf46a89e429fa77a380d5ee48babb8af2044196eff872825e84c0d4401357114
-test_truth_tracking_kalman[generic-False-0.0]__trackstates_kf.root: c2a351bb12b81a69549ca0229d36369cb63cbc53a924f0fd0520879d214b9134
-test_truth_tracking_kalman[generic-False-0.0]__tracksummary_kf.root: bf46a89e429fa77a380d5ee48babb8af2044196eff872825e84c0d4401357114
+test_refitting[generic]__tracksummary_gsf_refit.root: 9dd347fcab40d1045bd48e1d7e531fbc9f1e07a2e7e321f196250721befe086c
+test_truth_tracking_kalman[generic-False-0.0]__trackstates_kf.root: 4e49258ae95ef7b7c59ef155545323fbee6de3f160a0cd975225c0458ec27912
+test_truth_tracking_kalman[generic-False-0.0]__tracksummary_kf.root: 9dd347fcab40d1045bd48e1d7e531fbc9f1e07a2e7e321f196250721befe086c
 test_truth_tracking_kalman[generic-False-1000.0]__trackstates_kf.root: 0a2428ff260466f7fe4ea44863664afa3c7e34b0dc388e43ee096d132f3acefb
-test_truth_tracking_kalman[generic-False-1000.0]__tracksummary_kf.root: 055a74d2747d360398cc846cc2791204491528896de78cca66b188e3ff530dc1
-test_truth_tracking_kalman[generic-True-0.0]__trackstates_kf.root: c2a351bb12b81a69549ca0229d36369cb63cbc53a924f0fd0520879d214b9134
-test_truth_tracking_kalman[generic-True-0.0]__tracksummary_kf.root: bf46a89e429fa77a380d5ee48babb8af2044196eff872825e84c0d4401357114
+test_truth_tracking_kalman[generic-False-1000.0]__tracksummary_kf.root: 8be4bcc0f05c90ffeb4ea7bbb517adee217550d59c2eed89a48ed3b4c5145c54
+test_truth_tracking_kalman[generic-True-0.0]__trackstates_kf.root: 4e49258ae95ef7b7c59ef155545323fbee6de3f160a0cd975225c0458ec27912
+test_truth_tracking_kalman[generic-True-0.0]__tracksummary_kf.root: 9dd347fcab40d1045bd48e1d7e531fbc9f1e07a2e7e321f196250721befe086c
 test_truth_tracking_kalman[generic-True-1000.0]__trackstates_kf.root: 0a2428ff260466f7fe4ea44863664afa3c7e34b0dc388e43ee096d132f3acefb
-test_truth_tracking_kalman[generic-True-1000.0]__tracksummary_kf.root: 055a74d2747d360398cc846cc2791204491528896de78cca66b188e3ff530dc1
+test_truth_tracking_kalman[generic-True-1000.0]__tracksummary_kf.root: 8be4bcc0f05c90ffeb4ea7bbb517adee217550d59c2eed89a48ed3b4c5145c54
 test_truth_tracking_kalman[odd-False-0.0]__trackstates_kf.root: a34546ba6cfdbecc3bcf6f02ec782ebcc76f332070e7ff8a64207ed815f65c7e
 test_truth_tracking_kalman[odd-False-0.0]__tracksummary_kf.root: 7f1bb68b39e52da7a77ea295819fa3776e947568455338738c3a6436c2d7599c
 test_truth_tracking_kalman[odd-False-1000.0]__trackstates_kf.root: 0344aa50ba6c14152cf0f29b6f6da8af88fd61556a99baa62bef2fdbbc121ac8