WHAT COULD ROOT GEOMETRY OFFER ?

Andrei Gheata, LC Software WorkshopCERN 28-29 May 2009

Available in ROOT since 2001 – initiative of ALICE offline and ROOT teamsThe development mainly motivated by the need of a tool to unify the geometry description in relation with simulation transport engines, but not only.First presented at CHEP 2003 - Some of the bonuses were foreseen at the time …

A full-fledged geometry modeler

Features

A CSG hierarchical model based on an extended set of solid body primitives (shapes) 20 shape types supporting Boolean operations & scaling

Navigation functionality extensively tuned for performance and reliability

Several built-in features to ease-up detector geometry definition (divisions, assemblies, geometry builder GUI)

Full navigation functionality benchmarked and optimized for a big (~30) set of geometries coming from G3 Integrated in Virtual Monte Carlo framework , implemented for

most popular transportation engines (GEANT3, GEANT4 and FLUKA) via navigation interfaces

Parallel navigation available with minimal changes (already proved to work) – see CHEP’09 contribution #460

API available for other potential customers (reconstruction)

Other features

Dynamic activation of geometry details in navigation One does not need 2 geometry representations for coarse or detailed

geometry Native support for dynamic misalignment

Directly used in simulation and reconstruction High-performance geometry checking tools

Overlap checker, raytracing utilities Built-in support for geometry rendering

Hi-quality OpenGL visualization, client for event displays (see talk of Matevz Tadel)

Ray tracing for high-definition images ROOT I/O (fast) + import/export for other formats

GDML reader/writer Export as C++ code

Radionuclide support (elements composing materials and mixtures) Evolution in time according Bateman equation

Complete GUI library for geometry editing

ROOT geometry and simulation TGeo can act as navigator for G3, G4

and FLUKA via VMC framework Navigation fully validated against native

geometries – reported at CHEP Ongoing physics comparisons and

fine tunes (G4 physics lists) in ALICE In production in ALICE

Used by many other experiments

ROOT geometry and simulation TGeo can act as navigator for G3, G4

and FLUKA via VMC framework Navigation fully validated against native

geometries – reported at CHEP Ongoing physics comparisons and

fine tunes (G4 physics lists) in ALICE

ROOT geometry and reconstruction Tracking is using the full geometry to

compute material budget-related corrections ALICE has 4.3 Mio volumes in the

detailed geometry Alignment data is loaded on top of

the ideal geometry and used directly To apply corrections at the level of digits

(position) As input by alignment procedures that

produce corrections to alignment objects

Visualization & Event display Native OGL rendering

Supporting clipping, transparency, projections, …

Very good interactivity even for large level of detail

Used as component by EVE (see talk of Matevz) Very powerful and versatile event

display

Visualization & Event display

Instead of conclusions

Geometry is obviously something needed by several HEP SW components

The ROOT geometry package provides the functionality, API and interfaces required by most of them

Embedding big efforts for tuning and flawless quality, the tool is in production as core component in ALICE software Adopted also as geometry baseline by other

experiments