refactor: Refactor how the bound state covariance is handled without transport

Core/include/Acts/TrackFinding/CombinatorialKalmanFilter.hpp

@@ -572,7 +572,9 @@ class CombinatorialKalmanFilter {
         if (!boundStateRes.ok()) {
           return boundStateRes.error();
         }
-        auto boundState = *boundStateRes;
+        auto& boundState = *boundStateRes;
+        auto& [boundParams, jacobian, pathLength] = boundState;
+        boundParams.covariance() = state.stepping.cov;
 
         // Retrieve the previous tip and its state
         // The states created on this surface will have the common previous tip
@@ -940,9 +942,7 @@ class CombinatorialKalmanFilter {
       const auto& [boundParams, jacobian, pathLength] = boundState;
       // Fill the track state
       trackStateProxy.predicted() = boundParams.parameters();
-      if (boundParams.covariance().has_value()) {
-        trackStateProxy.predictedCovariance() = *boundParams.covariance();
-      }
+      trackStateProxy.predictedCovariance() = boundParams.covariance().value();
       trackStateProxy.jacobian() = jacobian;
       trackStateProxy.pathLength() = pathLength;
       // Set the surface

Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp

@@ -447,17 +447,14 @@ class Gx2Fitter {
               result.result = res.error();
               return;
             }
-            auto& [boundParams, jacobian, pathLength] = *res;
+            const auto& [boundParams, jacobian, pathLength] = *res;
 
             // Fill the track state
-            trackStateProxy.predicted() = std::move(boundParams.parameters());
-            if (boundParams.covariance().has_value()) {
-              trackStateProxy.predictedCovariance() =
-                  std::move(*boundParams.covariance());
-            }
+            trackStateProxy.predicted() = boundParams.parameters();
+            trackStateProxy.predictedCovariance() = state.stepping.cov;
 
-            trackStateProxy.jacobian() = std::move(jacobian);
-            trackStateProxy.pathLength() = std::move(pathLength);
+            trackStateProxy.jacobian() = jacobian;
+            trackStateProxy.pathLength() = pathLength;
           }
 
           // We have predicted parameters, so calibrate the uncalibrated input

Core/include/Acts/TrackFitting/KalmanFitter.hpp

@@ -744,17 +744,14 @@ class KalmanFitter {
           if (!res.ok()) {
             return res.error();
           }
-          auto& [boundParams, jacobian, pathLength] = *res;
+          const auto& [boundParams, jacobian, pathLength] = *res;
 
           // Fill the track state
-          trackStateProxy.predicted() = std::move(boundParams.parameters());
-          if (boundParams.covariance().has_value()) {
-            trackStateProxy.predictedCovariance() =
-                std::move(*boundParams.covariance());
-          }
+          trackStateProxy.predicted() = boundParams.parameters();
+          trackStateProxy.predictedCovariance() = state.stepping.cov;
 
-          trackStateProxy.jacobian() = std::move(jacobian);
-          trackStateProxy.pathLength() = std::move(pathLength);
+          trackStateProxy.jacobian() = jacobian;
+          trackStateProxy.pathLength() = pathLength;
         }
 
         // We have predicted parameters, so calibrate the uncalibrated input

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

@@ -10,6 +10,7 @@
 
 #include "Acts/EventData/MultiTrajectory.hpp"
 #include "Acts/EventData/SourceLink.hpp"
+#include "Acts/EventData/TrackParameters.hpp"
 #include "Acts/EventData/detail/CorrectedTransformationFreeToBound.hpp"
 #include "Acts/Surfaces/Surface.hpp"
 #include "Acts/Utilities/CalibrationContext.hpp"
@@ -59,17 +60,14 @@ auto kalmanHandleMeasurement(
                                          << " failed: " << res.error());
       return res.error();
     }
-    auto &[boundParams, jacobian, pathLength] = *res;
+    const auto &[boundParams, jacobian, pathLength] = *res;
 
     // Fill the track state
-    trackStateProxy.predicted() = std::move(boundParams.parameters());
-    if (boundParams.covariance().has_value()) {
-      trackStateProxy.predictedCovariance() =
-          std::move(*boundParams.covariance());
-    }
+    trackStateProxy.predicted() = boundParams.parameters();
+    trackStateProxy.predictedCovariance() = state.stepping.cov;
 
-    trackStateProxy.jacobian() = std::move(jacobian);
-    trackStateProxy.pathLength() = std::move(pathLength);
+    trackStateProxy.jacobian() = jacobian;
+    trackStateProxy.pathLength() = pathLength;
   }
 
   // We have predicted parameters, so calibrate the uncalibrated input
@@ -154,17 +152,14 @@ auto kalmanHandleNoMeasurement(
     if (!res.ok()) {
       return res.error();
     }
-    auto &[boundParams, jacobian, pathLength] = *res;
+    const auto &[boundParams, jacobian, pathLength] = *res;
 
     // Fill the track state
-    trackStateProxy.predicted() = std::move(boundParams.parameters());
-    if (boundParams.covariance().has_value()) {
-      trackStateProxy.predictedCovariance() =
-          std::move(*boundParams.covariance());
-    }
+    trackStateProxy.predicted() = boundParams.parameters();
+    trackStateProxy.predictedCovariance() = state.stepping.cov;
 
-    trackStateProxy.jacobian() = std::move(jacobian);
-    trackStateProxy.pathLength() = std::move(pathLength);
+    trackStateProxy.jacobian() = jacobian;
+    trackStateProxy.pathLength() = pathLength;
 
     // Set the filtered parameter index to be the same with predicted
     // parameter

Core/src/Propagator/detail/CovarianceEngine.cpp

@@ -50,17 +50,13 @@ Result<BoundState> detail::boundState(
   // Covariance transport
   std::optional<BoundSquareMatrix> cov = std::nullopt;
   if (covTransport) {
-    // Initialize the jacobian from start local to final local
-    fullTransportJacobian = BoundMatrix::Identity();
     // Calculate the jacobian and transport the covarianceMatrix to final local.
     // Then reinitialize the transportJacobian, derivatives and the
     // boundToFreeJacobian
     transportCovarianceToBound(geoContext, surface, boundCovariance,
                                fullTransportJacobian, freeTransportJacobian,
                                freeToPathDerivatives, boundToFreeJacobian,
                                freeParameters, freeToBoundCorrection);
-  }
-  if (boundCovariance != BoundSquareMatrix::Zero()) {
     cov = boundCovariance;
   }
 
@@ -82,16 +78,12 @@ CurvilinearState detail::curvilinearState(
   // Covariance transport
   std::optional<BoundSquareMatrix> cov = std::nullopt;
   if (covTransport) {
-    // Initialize the jacobian from start local to final local
-    fullTransportJacobian = BoundMatrix::Identity();
     // Calculate the jacobian and transport the covarianceMatrix to final local.
     // Then reinitialize the transportJacobian, derivatives and the
     // boundToFreeJacobian
     transportCovarianceToCurvilinear(
         boundCovariance, fullTransportJacobian, freeTransportJacobian,
         freeToPathDerivatives, boundToFreeJacobian, direction);
-  }
-  if (boundCovariance != BoundSquareMatrix::Zero()) {
     cov = boundCovariance;
   }
 

Tests/UnitTests/Core/Propagator/CovarianceEngineTests.cpp

@@ -110,12 +110,10 @@ BOOST_AUTO_TEST_CASE(covariance_engine_test) {
   BOOST_CHECK_EQUAL(parameters, startParameters);
 
   // Produce a curvilinear state without covariance matrix
-  auto covarianceBefore = covariance;
   auto curvResult = detail::curvilinearState(
       covariance, jacobian, transportJacobian, derivatives, boundToFreeJacobian,
       parameters, particleHypothesis, false, 1337.);
-  BOOST_CHECK(std::get<0>(curvResult).covariance().has_value());
-  BOOST_CHECK_EQUAL(*(std::get<0>(curvResult).covariance()), covarianceBefore);
+  BOOST_CHECK(!std::get<0>(curvResult).covariance().has_value());
   BOOST_CHECK_EQUAL(std::get<2>(curvResult), 1337.);
 
   // Reset
@@ -136,7 +134,7 @@ BOOST_AUTO_TEST_CASE(covariance_engine_test) {
   BOOST_CHECK_EQUAL(std::get<2>(curvResult), 1337.);
 
   // Produce a bound state without covariance matrix
-  covarianceBefore = covariance;
+  auto covarianceBefore = covariance;
   auto boundResult =
       detail::boundState(tgContext, *surface, covariance, jacobian,
                          transportJacobian, derivatives, boundToFreeJacobian,