algorithms/tracking/TrackerHitReconstruction.cc

0001 // SPDX-License-Identifier: LGPL-3.0-or-later
0002 // Copyright (C) 2022 Whitney Armstrong, Sylvester Joosten, Wouter Deconinck, Dmitry Romanov
0003
0004 #include "TrackerHitReconstruction.h"
0005
0006 #include <Evaluator/DD4hepUnits.h>
0007 #include <Math/GenVector/Cartesian3D.h>
0008 #include <Math/GenVector/DisplacementVector3D.h>
0009 #include <edm4eic/CovDiag3f.h>
0010 #include <edm4eic/EDM4eicVersion.h>
0011 #include <edm4hep/Vector3f.h>
0012 #include <fmt/core.h>
0013 #include <spdlog/common.h>
0014 #include <stddef.h>
0015 #include <iterator>
0016 #include <utility>
0017 #include <vector>
0018
0019 namespace eicrecon {
0020
0021 namespace {
0022     inline double get_resolution(const double pixel_size) {
0023         constexpr const double sqrt_12 = 3.4641016151;
0024         return pixel_size / sqrt_12;
0025     }
0026     inline double get_variance(const double pixel_size) {
0027         const double res = get_resolution(pixel_size);
0028         return res * res;
0029     }
0030 } // namespace
0031
0032 void TrackerHitReconstruction::init(const dd4hep::rec::CellIDPositionConverter* converter, std::shared_ptr<spdlog::logger>& logger) {
0033
0034     m_log = logger;
0035
0036     m_converter = converter;
0037 }
0038
0039 std::unique_ptr<edm4eic::TrackerHitCollection> TrackerHitReconstruction::process(const edm4eic::RawTrackerHitCollection& raw_hits) {
0040     using dd4hep::mm;
0041
0042     auto rec_hits { std::make_unique<edm4eic::TrackerHitCollection>() };
0043
0044     for (const auto& raw_hit : raw_hits) {
0045
0046         auto id = raw_hit.getCellID();
0047
0048         // Get position and dimension
0049         auto pos = m_converter->position(id);
0050         auto dim = m_converter->cellDimensions(id);
0051
0052         // >oO trace
0053         if(m_log->level() == spdlog::level::trace) {
0054             m_log->trace("position x={:.2f} y={:.2f} z={:.2f} [mm]: ", pos.x()/ mm, pos.y()/ mm, pos.z()/ mm);
0055             m_log->trace("dimension size: {}", dim.size());
0056             for (size_t j = 0; j < std::size(dim); ++j) {
0057                 m_log->trace(" - dimension {:<5} size: {:.2}",  j, dim[j]);
0058             }
0059         }
0060
0061         // Note about variance:
0062         //    The variance is used to obtain a diagonal covariance matrix.
0063         //    Note that the covariance matrix is written in DD4hep surface coordinates,
0064         //    *NOT* global position coordinates. This implies that:
0065         //      - XY segmentation: xx -> sigma_x, yy-> sigma_y, zz -> 0, tt -> 0
0066         //      - XZ segmentation: xx -> sigma_x, yy-> sigma_z, zz -> 0, tt -> 0
0067         //      - XYZ segmentation: xx -> sigma_x, yy-> sigma_y, zz -> sigma_z, tt -> 0
0068         //    This is properly in line with how we get the local coordinates for the hit
0069         //    in the TrackerSourceLinker.
0070  #if EDM4EIC_VERSION_MAJOR >= 7
0071        auto rec_hit =
0072  #endif
0073        rec_hits->create(
0074             raw_hit.getCellID(), // Raw DD4hep cell ID
0075             edm4hep::Vector3f{static_cast<float>(pos.x() / mm), static_cast<float>(pos.y() / mm), static_cast<float>(pos.z() / mm)}, // mm
0076             edm4eic::CovDiag3f{get_variance(dim[0] / mm), get_variance(dim[1] / mm), // variance (see note above)
0077             std::size(dim) > 2 ? get_variance(dim[2] / mm) : 0.},
0078                 static_cast<float>((double)(raw_hit.getTimeStamp()) / 1000.0), // ns
0079             m_cfg.timeResolution,                            // in ns
0080             static_cast<float>(raw_hit.getCharge() / 1.0e6),   // Collected energy (GeV)
0081             0.0F);                                       // Error on the energy
0082 #if EDM4EIC_VERSION_MAJOR >= 7
0083         rec_hit.setRawHit(raw_hit);
0084 #endif
0085
0086     }
0087
0088     return std::move(rec_hits);
0089 }
0090
0091 } // namespace eicrecon