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g2root - Man Page

convert GEANT geometry files to ROOT files


g2rootd [-f map_name] geant_name macro_name


You can convert a GEANT (see http://geant.cern.ch/ fore more on GEANT) geometry to ROOT geometry with the following steps


Run the interactive version of GEANT and produce a Zebra RZ file detector.geom, by typing the command:

Geant > rz/file 21 detector.geom on


Run the g2root program to convert the Zebra RZ file into a ROOT macro detector.C:

g2root detector.geom detector.C


Run the following ROOT session;

root [1] .x detector.C
root [2] detector.Draw()
root [3] c1.x3d()   // (this invokes the 3-d Root viewer)
root [4] TFile f("detector.root","NEW") //open a new root file
root [5] detector.Write() //Write the geometry structure
root [6] f.Write()

Note that the TNode structure currently in ROOT was not designed as a replacement for a true geometry package. The idea was mainly to draw simple geometries in event display programs. We are currently investigating several alternatives for a true & efficient geometry package supporting;


a disk data base with storage of multiple geometry versions


an interactive editor and viewer


with 3-d views


but also 2-d cut views


with interfaces to existing or future MC such as GEANT3 or GEANT4

A second program called gh2root (see http://root.cern/root/gh2root.html) generates automatically C++ code corresponding to the GEANT3 Zebra structures JSET, JVERTX, JKINE, JHITS and JDIGI.

See Also


The ROOT Users Guide

available from the main ROOT website:

Original Authors

The ROOT team (see web page above):

Rene Brun and Fons Rademakers


This manual page was written by Christian Holm Christensen <cholm@nbi.dk>, for the Debian GNU/Linux system (but may be used by others).

Referenced By


Version 3 ROOT