ITS: TrackExtension allow steering of cuts&directions

Author: f3sch

Detectors/ITSMFT/ITS/tracking/include/ITStracking/Configuration.h

@@ -94,11 +94,17 @@ struct TrackingParameters {
   unsigned long MaxMemory = 12000000000UL;
   float MaxChi2ClusterAttachment = 60.f;
   float MaxChi2NDF = 30.f;
-  bool UseTrackFollower = false;
   bool FindShortTracks = false;
   bool PerPrimaryVertexProcessing = false;
   bool SaveTimeBenchmarks = false;
   bool DoUPCIteration = false;
+  /// Cluster attachment
+  bool UseTrackFollower = false;
+  bool UseTrackFollowerTop = false;
+  bool UseTrackFollowerBot = false;
+  bool UseTrackFollowerMix = false;
+  float TrackFollowerNSigmaCutZ = 1.f;
+  float TrackFollowerNSigmaCutPhi = 1.f;
 };
 
 inline int TrackingParameters::CellMinimumLevel()

Detectors/ITSMFT/ITS/tracking/include/ITStracking/TrackingConfigParam.h

@@ -72,7 +72,9 @@ struct TrackerParamConfig : public o2::conf::ConfigurableParamHelper<TrackerPara
   float diamondPos[3] = {0.f, 0.f, 0.f};
   bool useDiamond = false;
   unsigned long maxMemory = 0;
-  int useTrackFollower = -1;
+  int useTrackFollower = -1;          // bit 0: allow mixing implies bits 1&2; bit 1: topwards; bit2: downwards; => 0 off
+  float trackFollowerNSigmaZ = 1.f;   // sigma in z-cut for track-following search rectangle
+  float trackFollowerNSigmaPhi = 1.f; // sigma in phi-cut for track-following search rectangle
   float cellsPerClusterLimit = -1.f;
   float trackletsPerClusterLimit = -1.f;
   int findShortTracks = -1;

Detectors/ITSMFT/ITS/tracking/src/Tracker.cxx

@@ -502,8 +502,16 @@ void Tracker::getGlobalConfiguration()
     if (tc.maxMemory) {
       params.MaxMemory = tc.maxMemory;
     }
-    if (tc.useTrackFollower >= 0) {
-      params.UseTrackFollower = tc.useTrackFollower;
+    if (tc.useTrackFollower > 0) {
+      params.UseTrackFollower = true;
+      // Bit 0: Allow for mixing of top&bot extension --> implies Bits 1&2 set
+      // Bit 1: Allow for top extension
+      // Bit 2: Allow for bot extension
+      params.UseTrackFollowerMix = ((tc.useTrackFollower & (1 << 0)) != 0);
+      params.UseTrackFollowerTop = ((tc.useTrackFollower & (1 << 1)) != 0);
+      params.UseTrackFollowerBot = ((tc.useTrackFollower & (1 << 2)) != 0);
+      params.TrackFollowerNSigmaCutZ = tc.trackFollowerNSigmaZ;
+      params.TrackFollowerNSigmaCutPhi = tc.trackFollowerNSigmaPhi;
     }
     if (tc.cellsPerClusterLimit >= 0) {
       params.CellsPerClusterLimit = tc.cellsPerClusterLimit;

Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx

@@ -679,10 +679,11 @@ void TrackerTraits::extendTracks(const int iteration)
     for (auto& track : mTimeFrame->getTracks(rof)) {
       auto backup{track};
       bool success{false};
-      if (track.getLastClusterLayer() != mTrkParams[iteration].NLayers - 1) {
+      // the order here biases towards top extension, tracks should probably be fitted separately in the directions and then compared.
+      if ((mTrkParams[iteration].UseTrackFollowerMix || mTrkParams[iteration].UseTrackFollowerTop) && track.getLastClusterLayer() != mTrkParams[iteration].NLayers - 1) {
         success = success || trackFollowing(&track, rof, true, iteration);
       }
-      if (track.getFirstClusterLayer() != 0) {
+      if ((mTrkParams[iteration].UseTrackFollowerMix || (mTrkParams[iteration].UseTrackFollowerBot && !success)) && track.getFirstClusterLayer() != 0) {
         success = success || trackFollowing(&track, rof, false, iteration);
       }
       if (success) {
@@ -888,7 +889,7 @@ bool TrackerTraits::trackFollowing(TrackITSExt* track, int rof, bool outward, co
       const float ePhi{o2::gpu::CAMath::Sqrt(hypoParam.getSigmaSnp2() / hypoParam.getCsp2())};
       const float z{hypoParam.getZ()};
       const float eZ{o2::gpu::CAMath::Sqrt(hypoParam.getSigmaZ2())};
-      const int4 selectedBinsRect{getBinsRect(iLayer, phi, mTrkParams[iteration].NSigmaCut * ePhi, z, mTrkParams[iteration].NSigmaCut * eZ)};
+      const int4 selectedBinsRect{getBinsRect(iLayer, phi, mTrkParams[iteration].TrackFollowerNSigmaCutPhi * ePhi, z, mTrkParams[iteration].TrackFollowerNSigmaCutZ * eZ)};
       if (selectedBinsRect.x == 0 && selectedBinsRect.y == 0 && selectedBinsRect.z == 0 && selectedBinsRect.w == 0) {
         continue;
       }
@@ -905,7 +906,6 @@ bool TrackerTraits::trackFollowing(TrackITSExt* track, int rof, bool outward, co
       }
 
       // check all clusters in search windows for possible new hypotheses
-#pragma omp parallel for num_threads(mNThreads) shared(hypotheses)
       for (int iPhiCount = 0; iPhiCount < phiBinsNum; iPhiCount++) {
         int iPhiBin = (selectedBinsRect.y + iPhiCount) % mTrkParams[iteration].PhiBins;
         const int firstBinIndex{mTimeFrame->mIndexTableUtils.getBinIndex(selectedBinsRect.x, iPhiBin)};
@@ -946,10 +946,7 @@ bool TrackerTraits::trackFollowing(TrackITSExt* track, int rof, bool outward, co
           }
           tbupdated.setChi2(tbupdated.getChi2() + predChi2); /// This is wrong for outward propagation as the chi2 refers to inward parameters
           tbupdated.setExternalClusterIndex(iLayer, nextCluster.clusterId, true);
-#pragma omp critical
-          {
-            hypotheses.emplace_back(tbupdated);
-          }
+          hypotheses.emplace_back(tbupdated);
         }
       }
     }