Fix ITS L2G matrix generation

Account for the difference between ITS chip and epitaxial layer matrices

Author: shahor02

Detectors/Align/include/Align/AlignableSensorITS.h

@@ -36,6 +36,8 @@ class AlignableSensorITS final : public AlignableSensor
   AlignableSensorITS(const char* name, int vid, int iid, Controller* ctr);
   ~AlignableSensorITS() final = default;
   void prepareMatrixT2L() final;
+  void prepareMatrixL2G(bool reco = false) final;
+  void prepareMatrixL2GIdeal() final;
   //
  protected:
   //

Detectors/Align/include/Align/Controller.h

@@ -282,6 +282,7 @@ class Controller final : public TObject
   int getDebugOutputLevel() const { return mDebugOutputLevel; }
   void setDebugOutputLevel(int i) { mDebugOutputLevel = i; }
   void setDebugStream(o2::utils::TreeStreamRedirector* d) { mDBGOut = d; }
+  o2::utils::TreeStreamRedirector* getDebugStream() { return mDBGOut; }
 
   void setTPCParam(const o2::gpu::GPUParam* par) { mTPCParam = par; }
   const o2::gpu::GPUParam* getTPCParam() const { return mTPCParam; }

Detectors/Align/src/AlignableSensorITS.cxx

@@ -66,5 +66,40 @@ void AlignableSensorITS::prepareMatrixT2L()
   setMatrixT2L(t2l);
 }
 
+void AlignableSensorITS::prepareMatrixL2G(bool reco)
+{
+  // Note that for ITS2 it is NOT the same as GeometryManager::getMatrix() (i.e. that of the alignable volule)
+  // since we need the matrix of epitaxial layer and not the whole chip
+  auto geom = o2::its::GeometryTGeo::Instance();
+  const auto* m = geom->extractMatrixSensor(getVolID());
+  if (!m) {
+    LOGP(fatal, "Failed on :GeometryTGeo::extractMatrixSensor({})", getVolID());
+  }
+  reco ? setMatrixL2GReco(*m) : setMatrixL2G(*m);
+}
+
+void AlignableSensorITS::prepareMatrixL2GIdeal()
+{
+  // Note that for ITS2 it is NOT the same as GeometryManager::getOriginalMatrix (i.e. that of the alignable volule)
+  // since we need the matrix of epitaxial layer and not the whole chip
+  auto geom = o2::its::GeometryTGeo::Instance();
+  TGeoHMatrix mtmp;
+  if (!base::GeometryManager::getOriginalMatrix(getSymName(), mtmp)) { // this is chip ideal matrix, not that of the epitaxial layer
+    LOG(fatal) << "Failed to find ideal L2G matrix for " << getSymName();
+  }
+  // we have to apply to it the difference between the aligner epitaxial layer matrix and that of the chip
+  const auto* malgSens = geom->extractMatrixSensor(getVolID());
+  if (!malgSens) {
+    LOGP(fatal, "Failed on :GeometryTGeo::extractMatrixSensor({})", getVolID());
+  }
+  const auto* malgChip = geom->getMatrix(getVolID());
+  // correct chip original matrix by the difference between aligneg chip and sensor matrices
+  // Sens_ideal = Chip_ideal * Chip_aligned^-1 * Sens_aligned
+  auto chAlignInv = malgChip->Inverse();
+  chAlignInv.Multiply(*malgSens);
+  mtmp.Multiply(chAlignInv);
+  setMatrixL2GIdeal(mtmp);
+}
+
 } // namespace align
 } // namespace o2

Detectors/ITSMFT/ITS/base/include/ITSBase/GeometryTGeo.h

@@ -338,7 +338,6 @@ class GeometryTGeo : public o2::itsmft::GeometryTGeo
 
   TString getMatrixPath(int index) const;
 
- protected:
   /// Get the transformation matrix of the SENSOR (not necessary the same as the chip)
   /// for a given chip 'index' by quering the TGeoManager
   TGeoHMatrix* extractMatrixSensor(int index) const;
@@ -349,6 +348,7 @@ class GeometryTGeo : public o2::itsmft::GeometryTGeo
   // get sensor tracking frame alpha and x
   void extractSensorXAlpha(int isn, float& x, float& alp);
 
+ protected:
   /// This routine computes the layer number a given the chip index
   /// \param int index The chip index number, starting from zero.
   /// \param int indexInLr The chip index inside a layer, starting from zero.