Move cluster error to weighted mean position error, based on cell size

cms-sw · Nov 28, 2022 · 3342528 · 3342528
1 parent 71654b0
commit 3342528
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Showing 3 changed files with 18 additions and 3 deletions.
diff --git a/DataFormats/FTLRecHit/interface/FTLCluster.h b/DataFormats/FTLRecHit/interface/FTLCluster.h
@@ -127,6 +127,18 @@ class FTLCluster {
     return weighted_mean(this->theHitENERGY, y_pos);
   }
 
+  inline float positionError(const float sigmaPos) const {
+    float sumW2(0.f), sumW(0.f);
+    for (const auto& hitW : theHitENERGY) {
+      sumW2 += hitW * hitW;
+      sumW += hitW;
+    }
+    if (sumW > 0)
+      return sigmaPos * std::sqrt(sumW2) / sumW;
+    else
+      return -999.f;
+  }
+
   inline float time() const {
     auto t = [this](unsigned int i) { return this->theHitTIME[i]; };
     return weighted_mean(this->theHitENERGY, t);

diff --git a/RecoLocalFastTime/FTLClusterizer/interface/MTDCPEBase.h b/RecoLocalFastTime/FTLClusterizer/interface/MTDCPEBase.h
@@ -80,6 +80,8 @@ class MTDCPEBase : public MTDClusterParameterEstimator {
   virtual TimeValue clusterTime(DetParam const& dp, ClusterParam& cp) const;
   virtual TimeValueError clusterTimeError(DetParam const& dp, ClusterParam& cp) const;
 
+  static constexpr float sigma_flat = 1.f / std::sqrt(12.f);
+
 protected:
   //---------------------------------------------------------------------------
   //  Data members

diff --git a/RecoLocalFastTime/FTLClusterizer/src/MTDCPEBase.cc b/RecoLocalFastTime/FTLClusterizer/src/MTDCPEBase.cc
@@ -66,10 +66,11 @@ LocalPoint MTDCPEBase::localPosition(DetParam const& dp, ClusterParam& cp) const
 }
 
 LocalError MTDCPEBase::localError(DetParam const& dp, ClusterParam& cp) const {
-  constexpr double one_over_twelve = 1. / 12.;
   MeasurementPoint pos(cp.theCluster->x(), cp.theCluster->y());
-  MeasurementError simpleRect(one_over_twelve, 0, one_over_twelve);
-  return dp.theTopol->localError(pos, simpleRect);
+  float sigma2 = cp.theCluster->positionError(sigma_flat);
+  sigma2 *= sigma2;
+  MeasurementError posErr(sigma2, 0, sigma2);
+  return dp.theTopol->localError(pos, posErr);
 }
 
 MTDCPEBase::TimeValue MTDCPEBase::clusterTime(DetParam const& dp, ClusterParam& cp) const {