CATFinderModule.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#include <tracking/modules/CATFinder/CATFinderModule.h>
 
#include <tracking/dbobjects/CATFinderParameters.h>
#include <tracking/gnnFinder/Utils.h>
#include <tracking/dataobjects/RecoHitInformation.h>
#include <tracking/dataobjects/RecoTrack.h>
 
#include <cdc/dataobjects/CDCHit.h>
#include <cdc/geometry/CDCGeometryPar.h>
#include <framework/database/DBAccessorBase.h>
#include <framework/database/DBObjPtr.h>
#include <framework/logging/Logger.h>
 
#include <algorithm>
#include <cmath>
#include <cstdint>
#include <numeric>
#include <utility>
#include <vector>
 
#include <Math/Vector3D.h>
#include <TMatrixDSym.h>
 
using namespace Belle2;
using Belle2::MVA::ONNX::Tensor;
 
REG_MODULE(CATFinder);
 
CATFinderModule::CATFinderModule() : Module()
{
  setDescription("The GNN-based CDC AI Track Finder, also known as CATFinder.");
  addParam("recoTracksStoreArrayName", m_CDCRecoTracksName, "Name of the output store array of CDC RecoTrack.",
           m_CDCRecoTracksName);
  addParam("catFinderWeightfileName", m_catFinderWeightfileName,
           "Name of the CATFinder weightfile as stored in the conditions database.",
           m_catFinderWeightfileName);
}
 
void CATFinderModule::initialize()
{
  m_CDCHits.isRequired();
  m_wireHitVector.isRequired();
  m_recoHitInformations.registerInDataStore();
  m_CDCRecoTracks.registerInDataStore(m_CDCRecoTracksName);
  m_CDCHits.registerRelationTo(m_CDCRecoTracks);
  m_recoHitInformations.registerRelationTo(m_CDCHits);
  m_CDCRecoTracks.registerRelationTo(m_recoHitInformations);
}
 
void CATFinderModule::beginRun()
{
  DBObjPtr<CATFinderParameters> parameters;
  if (not parameters.isValid())
    B2FATAL("CATFinderParameters is not valid");
 
  auto weightfile = DBAccessorBase(DBStoreEntry::c_RawFile, m_catFinderWeightfileName, true);
  const std::string filename = weightfile.getFilename();
  if (filename == "")
    B2FATAL(m_catFinderWeightfileName << " is not valid");
 
  // Get the relevant parameters
  m_tdcOffset               = parameters->getTDCOffset();
  m_tdcScale                = parameters->getTDCScale();
  m_adcClip                 = parameters->getADCClip();
  m_slayerScale             = parameters->getSLayerScale();
  m_clayerScale             = parameters->getCLayerScale();
  m_layerScale              = parameters->getLayerScale();
  m_spatialCoordinatesScale = parameters->getSpatialCoordinatesScale();
  m_nInputFeatures          = parameters->getNInputFeatures();
  m_latentSpaceNDim         = parameters->getLatentSpaceNDim();
  m_tBeta                   = parameters->getTBeta();
  m_tDistance               = parameters->getTDistance();
  m_maxRadius               = parameters->getMaxRadius();
  m_minNumberHits           = parameters->getMinNumberHits();
  m_inputTFeaturesName      = parameters->getInputTFeaturesName();
  m_outputTBetaName         = parameters->getOutputTBetaName();
  m_outputTCoordinatesName  = parameters->getOutputTCoordinatesName();
  m_outputTMomentumName     = parameters->getOutputTMomentumName();
  m_outputTVertexName       = parameters->getOutputTVertexName();
  m_outputTChargeName       = parameters->getOutputTChargeName();
 
  // Get the weightfile and initialize the ONNX session
 
  m_session = std::make_unique<MVA::ONNX::Session>(filename.c_str());
}
 
void CATFinderModule::event()
{
  CDC::CDCGeometryPar& cdcGeometryPar = CDC::CDCGeometryPar::Instance();
 
  const std::vector<TrackingUtilities::CDCWireHit>& wireHitVector = *m_wireHitVector;
 
  // Use only hits that are not marked as "taken" or "background"
  unsigned int nHits = 0;
  for (const auto& wireHit : wireHitVector) {
    const auto& cell = wireHit.getAutomatonCell();
    if (not(cell.hasTakenFlag() or cell.hasBackgroundFlag()))
      nHits++;
  }
 
  // Nothing to do if there are no hits left...
  if (nHits == 0)
    return;
 
  // Input tensore: features per hit
  auto input_t    = Tensor<float>::make_shared({nHits, m_nInputFeatures});
  // Output tensor: condensation score
  auto beta_t     = Tensor<float>::make_shared({nHits, 1});
  // Output tensor: predicted coordinates in the latent space
  auto coord_t    = Tensor<float>::make_shared({nHits, 3});
  // Output tensor: predicted momentum
  auto momentum_t = Tensor<float>::make_shared({nHits, 3});
  // Output tensor: predicted "vertex"
  auto vertex_t   = Tensor<float>::make_shared({nHits, 3});
  // Output tensor: predicted charge
  auto charge_t   = Tensor<float>::make_shared({nHits, 1});
 
  // Map from tensor row index back to the original wireHitVector index,
  // needed later when adding CDC hits to the RecoTrack
  std::vector<unsigned int> tensorIndexToHitIndex;
  tensorIndexToHitIndex.reserve(nHits);
 
  unsigned int iHit = 0;
  for (unsigned int iWireHit = 0; iWireHit < wireHitVector.size(); ++iWireHit) {
 
    // Again: skip the hits that are not marked as "taken" or "background"
    const auto& cell = wireHitVector[iWireHit].getAutomatonCell();
    if (cell.hasTakenFlag() or cell.hasBackgroundFlag())
      continue;
 
    // Prepare the input features
    const CDCHit* cdcHit = wireHitVector[iWireHit].getHit();
    const unsigned short clayer = cdcHit->getICLayer();
    const unsigned short wire   = cdcHit->getIWire();
    const auto wirePos = cdcGeometryPar.c_Aligned;
 
    const double tdc_scaled  = (static_cast<double>(cdcHit->getTDCCount()) - m_tdcOffset) / m_tdcScale;
    const double adc_clipped = cdcHit->getADCCount() > m_adcClip
                               ? 1.
                               : static_cast<double>(cdcHit->getADCCount()) / m_adcClip;
 
    const B2Vector3D posForward  = cdcGeometryPar.wireForwardPosition(clayer, wire, wirePos);
    const B2Vector3D posBackward = cdcGeometryPar.wireBackwardPosition(clayer, wire, wirePos);
 
    // Prepare the tensor
    input_t->at({iHit, 0}) = 0.5 * (posForward.x() + posBackward.x()) / m_spatialCoordinatesScale;
    input_t->at({iHit, 1}) = 0.5 * (posForward.y() + posBackward.y()) / m_spatialCoordinatesScale;
    input_t->at({iHit, 2}) = tdc_scaled;
    input_t->at({iHit, 3}) = adc_clipped;
    input_t->at({iHit, 4}) = static_cast<double>(cdcHit->getISuperLayer()) / m_slayerScale;
    input_t->at({iHit, 5}) = static_cast<double>(clayer)                   / m_clayerScale;
    input_t->at({iHit, 6}) = static_cast<double>(cdcHit->getILayer())      / m_layerScale;
 
    tensorIndexToHitIndex.push_back(iWireHit);
    ++iHit;
  }
 
  B2DEBUG(29, "CDCWireHits in the event: " << nHits);
  if (nHits != iHit)
    B2ERROR("Different number of hits: something went wrong...");
 
  // Run the GNN inference
  m_session->run(
  {{m_inputTFeaturesName, input_t}},
  {{m_outputTBetaName, beta_t}, {m_outputTCoordinatesName, coord_t}, {m_outputTMomentumName, momentum_t}, {m_outputTVertexName, vertex_t}, {m_outputTChargeName, charge_t}}
  );
 
  // Build an index array sorted by descending beta so we process the most probable condensation points first
  std::vector<unsigned int> betaIndices(nHits);
  std::iota(betaIndices.begin(), betaIndices.end(), 0);
  std::sort(betaIndices.begin(), betaIndices.end(),
  [&](unsigned int i1, unsigned int i2) { return beta_t->at({i1, 0}) > beta_t->at({i2, 0}); });
 
  // A hit is a candidate condensation point only if its beta exceeds the threshold
  std::vector<uint8_t> selectedBetas(nHits);
  for (unsigned int i = 0; i < nHits; ++i)
    selectedBetas[i] = static_cast<uint8_t>(beta_t->at({i, 0}) > m_tBeta);
 
  // A new condensation point is accepted only if it lies farther than m_tDistance
  // from every already-accepted point in latent coordinate space
  std::vector<unsigned int> conPointIndices;
  const float thresholdSquared = m_tDistance * m_tDistance;
 
  // Returns true if hit i is outside the exclusion radius of every accepted condensation point
  auto isOutOfRadius = [&](unsigned int i) {
    for (unsigned int iConPoint : conPointIndices) {
      double d = 0.0;
      d += (coord_t->at({i, 0}) - coord_t->at({iConPoint, 0})) * (coord_t->at({i, 0}) - coord_t->at({iConPoint, 0}));
      d += (coord_t->at({i, 1}) - coord_t->at({iConPoint, 1})) * (coord_t->at({i, 1}) - coord_t->at({iConPoint, 1}));
      d += (coord_t->at({i, 2}) - coord_t->at({iConPoint, 2})) * (coord_t->at({i, 2}) - coord_t->at({iConPoint, 2}));
      if (d <= thresholdSquared)
        return false;
    }
    return true;
  };
 
  for (unsigned int i = 0; i < betaIndices.size(); ++i) {
    unsigned int iBeta = betaIndices[i];
    if (!selectedBetas[iBeta])
      continue;  // Below the beta threshold: not a condensation point candidate
    if (conPointIndices.empty() or isOutOfRadius(iBeta))
      conPointIndices.push_back(iBeta);  // Accept as a new condensation point
    else
      selectedBetas[iBeta] = 0;  // Too close to an existing seed: let's discard it
  }
  B2DEBUG(29, "Condensation points in the event: " << conPointIndices.size());
 
  // Convert the condensation points into RecoTracks: one condensation point -> one RecoTrack
  for (unsigned int iConPoint : conPointIndices) {
 
    std::vector<GNNFinder::Utils::KDTHit> kdtHits;
    kdtHits.reserve(nHits);
 
    // Collect all hits whose clustering coordinates fall within m_maxRadius of this seed
    for (unsigned int i = 0; i < nHits; ++i) {
      const double dx = coord_t->at({iConPoint, 0}) - coord_t->at({i, 0});
      const double dy = coord_t->at({iConPoint, 1}) - coord_t->at({i, 1});
      const double dz = coord_t->at({iConPoint, 2}) - coord_t->at({i, 2});
      if (std::hypot(dx, dy, dz) < m_maxRadius) {
        // Store the wire X and Y coordinatres together with the tensor row index for later lookup
        kdtHits.push_back({input_t->at({i, 0}), input_t->at({i, 1}), static_cast<int>(i)});
      }
    }
 
    // Reject tracks with too few hits
    if (kdtHits.size() < m_minNumberHits)
      continue;
 
    // Retrieve predicted momentum, vertex and charge from the condensation point's output
    const ROOT::Math::XYZVector momentum(
      momentum_t->at({iConPoint, 0}), momentum_t->at({iConPoint, 1}), momentum_t->at({iConPoint, 2}));
    const ROOT::Math::XYZVector position(
      vertex_t->at({iConPoint, 0}) * m_spatialCoordinatesScale,
      vertex_t->at({iConPoint, 1}) * m_spatialCoordinatesScale,
      vertex_t->at({iConPoint, 2}) * m_spatialCoordinatesScale);
    const int charge = (charge_t->at({iConPoint, 0}) >= 0.5) ? 1 : -1;
 
    B2DEBUG(29, LogVar("Condensation point", iConPoint) << LogVar("Attached hits", kdtHits.size())
            << LogVar("Momentum", std::sqrt(momentum.Mag2())) << LogVar("Vertex", std::sqrt(position.Mag2()))
            << LogVar("Charge", charge));
 
    if (std::isnan(position.X()) or std::isnan(momentum.X())) {
      B2WARNING("Skipping track with NaN values.");
      continue;
    }
 
    // Order hits along the helix from the innermost CDC wall outward,
    // starting from where the predicted trajectory intersects the inner wall
    GNNFinder::Utils::HitOrderer hitOrderer;
    auto [startingX, startingY] = GNNFinder::Utils::intersectCylinderXY(position, momentum,
                                  16);  // TODO: find a better way to represent 16...
    std::vector<int> sortedIndices =
      hitOrderer.orderHits(startingX, startingY, std::move(kdtHits));
 
    // Create a new RecoTrack and seed it with the network predictions
    RecoTrack* cdcRecotrack = m_CDCRecoTracks.appendNew();
    cdcRecotrack->setPositionAndMomentum(position, momentum);
    cdcRecotrack->setChargeSeed(charge);
 
    // Use a loose covariance matrix as the seed uncertainty
    auto seedCovariance = TMatrixDSym(6);
    for (int j = 0; j < 6; ++j)
      for (int k = 0; k < 6; ++k)
        seedCovariance[j][k] = 1e-1;
    cdcRecotrack->setSeedCovariance(seedCovariance);
 
    // Add CDC hits in the sorted order
    int iRecoTrackHit = 0;
    for (int tensorIndex : sortedIndices) {
      cdcRecotrack->addCDCHit(wireHitVector[tensorIndexToHitIndex[tensorIndex]].getHit(), iRecoTrackHit);
      ++iRecoTrackHit;
    }
  }
}