PixelThresholdClusterizer.cc

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//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

// Our own includes
#include "RecoLocalTracker/SiPixelClusterizer/interface/PixelThresholdClusterizer.h"
#include "RecoLocalTracker/SiPixelClusterizer/interface/SiPixelArrayBuffer.h"
#include "CondFormats/SiPixelObjects/interface/SiPixelGainCalibrationOffline.h"
// Geometry
#include "Geometry/TrackerGeometryBuilder/interface/PixelGeomDetUnit.h"
#include "Geometry/CommonTopologies/interface/PixelTopology.h"
//#include "Geometry/CommonTopologies/RectangularPixelTopology.h"

// STL
#include <stack>
#include <vector>
#include <iostream>
using namespace std;

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
PixelThresholdClusterizer::PixelThresholdClusterizer
  (edm::ParameterSet const& conf) :
    conf_(conf), bufferAlreadySet(false), theNumOfRows(0), theNumOfCols(0), detid_(0) 
{
  // Get thresholds in electrons
  thePixelThreshold   = 
    conf_.getParameter<int>("ChannelThreshold");
  theSeedThreshold    = 
    conf_.getParameter<int>("SeedThreshold");
  theClusterThreshold = 
    conf_.getParameter<double>("ClusterThreshold");
  theConversionFactor = 
    conf_.getParameter<int>("VCaltoElectronGain");
  theOffset = 
    conf_.getParameter<int>("VCaltoElectronOffset");
  
  
  // Get the constants for the miss-calibration studies
  doMissCalibrate=conf_.getUntrackedParameter<bool>("MissCalibrate",true); 
  doSplitClusters = conf.getParameter<bool>("SplitClusters");
  theBuffer.setSize( theNumOfRows, theNumOfCols );
}
PixelThresholdClusterizer::~PixelThresholdClusterizer() {}

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
bool PixelThresholdClusterizer::setup(const PixelGeomDetUnit * pixDet) 
{
  // Cache the topology.
  const PixelTopology & topol = pixDet->specificTopology();
  
  // Get the new sizes.
  int nrows = topol.nrows();      // rows in x
  int ncols = topol.ncolumns();   // cols in y
  
  theNumOfRows = nrows;  // Set new sizes
  theNumOfCols = ncols;
  
  if ( nrows > theBuffer.rows() || 
       ncols > theBuffer.columns() ) 
    { // change only when a larger is needed
      //if( nrows != theNumOfRows || ncols != theNumOfCols ) {
      //cout << " PixelThresholdClusterizer: pixel buffer redefined to " 
      // << nrows << " * " << ncols << endl;      
      //theNumOfRows = nrows;  // Set new sizes
      //theNumOfCols = ncols;
      // Resize the buffer
      theBuffer.setSize(nrows,ncols);  // Modify
      bufferAlreadySet = true;
    }
  
  return true;   
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
void PixelThresholdClusterizer::clusterizeDetUnit( const edm::DetSet<PixelDigi> & input,
                           const PixelGeomDetUnit * pixDet,
                           const std::vector<short>& badChannels,
                                                   edmNew::DetSetVector<SiPixelCluster>::FastFiller& output) {
  
  DigiIterator begin = input.begin();
  DigiIterator end   = input.end();
  
  // Do not bother for empty detectors
  //if (begin == end) cout << " PixelThresholdClusterizer::clusterizeDetUnit - No digis to clusterize";
  
  //  Set up the clusterization on this DetId.
  if ( !setup(pixDet) ) 
    return;
  
  detid_ = input.detId();
  
  //  Copy PixelDigis to the buffer array; select the seed pixels
  //  on the way, and store them in theSeeds.
  copy_to_buffer(begin, end);
  
  //  At this point we know the number of seeds on this DetUnit, and thus
  //  also the maximal number of possible clusters, so resize theClusters
  //  in order to make vector<>::push_back() efficient.
  // output.reserve ( theSeeds.size() ); //GPetruc: It is better *not* to reserve, with the new DetSetVector!
  
  
  //  Loop over all seeds.  TO DO: wouldn't using iterators be faster?
  //  edm::LogError("PixelThresholdClusterizer") <<  "Starting clusterizing" << endl;
  for (unsigned int i = 0; i < theSeeds.size(); i++) 
    {
      
      // Gavril : The charge of seeds that were already inlcuded in clusters is set to 1 electron
      // so we don't want to call "make_cluster" for these cases 
      if ( theBuffer(theSeeds[i]) >= theSeedThreshold ) 
    {  // Is this seed still valid?
      //  Make a cluster around this seed
      SiPixelCluster cluster = make_cluster( theSeeds[i] , output);
      
      //  Check if the cluster is above threshold  
      // (TO DO: one is signed, other unsigned, gcc warns...)
      if ( cluster.charge() >= theClusterThreshold) 
        {
          //    cout << "putting in this cluster" << endl;
          output.push_back( cluster );
        }
    }
    }
  
  // Erase the seeds.
  theSeeds.clear();
  
  //  Need to clean unused pixels from the buffer array.
  clear_buffer(begin, end);
  
}

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
void PixelThresholdClusterizer::clear_buffer( DigiIterator begin, DigiIterator end ) 
{
  for(DigiIterator di = begin; di != end; ++di ) 
    {
      theBuffer.set_adc( di->row(), di->column(), 0 );   // reset pixel adc to 0
    }
}

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
void PixelThresholdClusterizer::copy_to_buffer( DigiIterator begin, DigiIterator end ) 
{
  for(DigiIterator di = begin; di != end; ++di) 
    {
      int row = di->row();
      int col = di->column();
      int adc = calibrate(di->adc(),col,row); // convert ADC -> electrons
      if ( adc >= thePixelThreshold) 
    {
      theBuffer.set_adc( row, col, adc);
      if ( adc >= theSeedThreshold) 
        { 
          theSeeds.push_back( SiPixelCluster::PixelPos(row,col) );
        }
    }
    }
}

//----------------------------------------------------------------------------
// Calibrate adc counts to electrons
//-----------------------------------------------------------------
int PixelThresholdClusterizer::calibrate(int adc, int col, int row) 
{
  int electrons = 0;
  
  if ( doMissCalibrate ) 
    {
      // do not perform calibration if pixel is dead!
      
      if ( !theSiPixelGainCalibrationService_->isDead(detid_,col,row) && 
       !theSiPixelGainCalibrationService_->isNoisy(detid_,col,row) )
    {
      
      // Linear approximation of the TANH response
      // Pixel(0,0,0)
      //const float gain = 2.95; // 1 ADC = 2.95 VCALs (1/0.339)
      //const float pedestal = -83.; // -28/0.339
      // Roc-0 average
      //const float gain = 1./0.357; // 1 ADC = 2.80 VCALs 
      //const float pedestal = -28.2 * gain; // -79.
      
      float DBgain     = theSiPixelGainCalibrationService_->getGain(detid_, col, row);
      float DBpedestal = theSiPixelGainCalibrationService_->getPedestal(detid_, col, row) * DBgain;
      
      
      // Roc-6 average
      //const float gain = 1./0.313; // 1 ADC = 3.19 VCALs 
      //const float pedestal = -6.2 * gain; // -19.8
      // 
      float vcal = adc * DBgain - DBpedestal;
      
      // atanh calibration 
      // Roc-6 average
      //const float p0 = 0.00492;
      //const float p1 = 1.998;
      //const float p2 = 90.6;
      //const float p3 = 134.1; 
      // Roc-6 average
      //const float p0 = 0.00382;
      //const float p1 = 0.886;
      //const float p2 = 112.7;
      //const float p3 = 113.0; 
      //float vcal = ( atanh( (adc-p3)/p2) + p1)/p0;
      
      electrons = int( vcal * theConversionFactor + theOffset); 
    }
    }
  else 
    { // No misscalibration in the digitizer
      // Simple (default) linear gain 
      const float gain = 135.; // 1 ADC = 135 electrons
      const float pedestal = 0.; //
      electrons = int(adc * gain + pedestal);
    }
  
  return electrons;
}

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
SiPixelCluster 
PixelThresholdClusterizer::make_cluster( const SiPixelCluster::PixelPos& pix, 
                     edmNew::DetSetVector<SiPixelCluster>::FastFiller& output) 
{
  
  //First we acquire the seeds for the clusters
  int seed_adc;
  stack<SiPixelCluster::PixelPos, vector<SiPixelCluster::PixelPos> > pixel_stack;
  stack<SiPixelCluster::PixelPos, vector<SiPixelCluster::PixelPos> > dead_pixel_stack;
  
  //The individual modules have been loaded into a buffer.
  //After each pixel has been considered by the clusterizer, we set the adc count to 1
  //to mark that we have already considered it.
  //The only difference between dead/noisy pixels and standard ones is that for dead/noisy pixels,
  //We consider the charge of the pixel to always be zero.

  if ( theSiPixelGainCalibrationService_->isDead(detid_,pix.col(),pix.row()) || 
       theSiPixelGainCalibrationService_->isNoisy(detid_,pix.col(),pix.row()) )
    {
      seed_adc = 0;
      theBuffer.set_adc(pix, 1);
    }
  else
    {
      seed_adc = theBuffer(pix.row(), pix.col());
      theBuffer.set_adc( pix, 1);
    }
  
  SiPixelCluster cluster( pix, seed_adc );
  
  //Here we search all pixels adjacent to all pixels in the cluster.
  pixel_stack.push( pix);
  bool dead_flag = false;
  while ( ! pixel_stack.empty()) 
    {
      //This is the standard algorithm to find and add a pixel
      SiPixelCluster::PixelPos curpix = pixel_stack.top(); pixel_stack.pop();
      for ( int r = curpix.row()-1; r <= curpix.row()+1; ++r) 
    {
      for ( int c = curpix.col()-1; c <= curpix.col()+1; ++c) 
        {
          if ( theBuffer(r,c) >= thePixelThreshold) 
        {
          
          SiPixelCluster::PixelPos newpix(r,c);
          cluster.add( newpix, theBuffer(r,c));
          theBuffer.set_adc( newpix, 1);
          pixel_stack.push( newpix);
        }
         

          /* //Commenting out the addition of dead pixels to the cluster until further testing -- dfehling 06/09
          //Check on the bounds of the module; this is to keep the isDead and isNoisy modules from returning errors 
          else if(r>= 0 && c >= 0 && (r <= (theNumOfRows-1.)) && (c <= (theNumOfCols-1.))){ 
          //Check for dead/noisy pixels check that the buffer is not -1 (already considered).  Check whether we want to split clusters separated by dead pixels or not.
          if((theSiPixelGainCalibrationService_->isDead(detid_,c,r) || theSiPixelGainCalibrationService_->isNoisy(detid_,c,r)) && theBuffer(r,c) != 1){
          
          //If a pixel is dead or noisy, check to see if we want to split the clusters or not.  
          //Push it into a dead pixel stack in case we want to split the clusters.  Otherwise add it to the cluster.
          //If we are splitting the clusters, we will iterate over the dead pixel stack later.
          
          SiPixelCluster::PixelPos newpix(r,c);
          if(!doSplitClusters){
          
          cluster.add(newpix, theBuffer(r,c));}
          else if(doSplitClusters){
          dead_pixel_stack.push(newpix);
          dead_flag = true;}
          
          theBuffer.set_adc(newpix, 1);
          } 
          
          }
          */
        


        }
    }
      
    }
  
  //Here we split the cluster, if the flag to do so is set and we have found a dead or noisy pixel.
  
  if (dead_flag && doSplitClusters) 
    {
      //Set the first cluster equal to the existing cluster.
      SiPixelCluster first_cluster = cluster;
      bool have_second_cluster = false;
      while ( !dead_pixel_stack.empty() )
    {
      //consider each found dead pixel
      SiPixelCluster::PixelPos deadpix = dead_pixel_stack.top(); dead_pixel_stack.pop();
      theBuffer.set_adc(deadpix, 1);
     
      //Clusterize the split cluster using the dead pixel as a seed
      SiPixelCluster second_cluster = make_cluster(deadpix, output);
      
      //If both clusters would normally have been found by the clusterizer, put them into output
      if ( second_cluster.charge() >= theClusterThreshold && 
           first_cluster.charge() >= theClusterThreshold )
        {
          output.push_back( second_cluster );
          have_second_cluster = true;   
        }
      
      //We also want to keep the merged cluster in data and let the RecHit algorithm decide which set to keep
      //This loop adds the second cluster to the first.
      const std::vector<SiPixelCluster::Pixel>& branch_pixels = second_cluster.pixels();
      for ( unsigned int i = 0; i<branch_pixels.size(); i++)
        {
          int temp_x = branch_pixels[i].x;
          int temp_y = branch_pixels[i].y;
          int temp_adc = branch_pixels[i].adc;
          SiPixelCluster::PixelPos newpix(temp_x, temp_y);
          cluster.add(newpix, temp_adc);}
    }
      
      //Remember to also add the first cluster if we added the second one.
      if ( first_cluster.charge() >= theClusterThreshold && have_second_cluster) 
    {
      output.push_back( first_cluster );
    }
    }
  
  return cluster;
}