HOWTO save tracking results to an HDDM or EVIO file for later playback

Introduction

Full reconstruction of GlueX data is dominated by charged track reconstruction. As such, it is useful to save the (expensively produced) results from tracking to an output file that can be re-read later. Recently (May 2010) two mechanisms were checked into the repository to meet this need. One writes out HDDM formatted files (the format used by the GlueX Simulation) and the other writes out EVIO formatted files (the format that the DAQ system will store the raw data in). This HOWTO documents how to save and read in files of both types.

HDDM Files

One can write out HDDM formatted files with reconstructed charged tracks (DTrackTimeBased objects) using the danahddm plugin.

NOTE: THIS CAN ONLY BE USED WHEN THE INPUT FILE IS ITSELF AND HDDM FILE (see below)

The plugin is not currently built by default, but may be in the near future once it has been deemed more stable. The source code for the plugin is kept in:

sim-recon/src/programs/Utilities/plugins/danahddm

To build the plugin, make sure you have a recent version of the source code (rev. 6363 or later) and, (re)build the entire source tree, and do a "make" in the danahddm directory. It is important to build the full source tree since the data model was modified to contain a reconView branch for hold reconstructied data. This first incarnation only saves DTrackTimeBased objects, but presumably others will be added later.