Configuration

ViSAGE reads all simulation parameters directly from the SAGE .par file. No separate config file is needed.

CLI options

Option	Default	Description
--par FILE	(required unless --lightcone)	Path to SAGE .par file. Omit both --par and --lightcone to start in Launch Mode
--lightcone FILE	—	Path to a cli_lightcone HDF5 output file — opens the full Explore UI on the lightcone instead of a SAGE box
--snap N	last snap	Initial snapshot number
--port N	8080	Trame server port
--n-jobs N	usable CPUs − 1	Parallel workers for halo loading (respects a cluster job's CPU allocation)
--cache-gb GB	half of RAM	Snapshot cache budget; half of physical RAM, or of an HPC job's memory limit. Also VISAGE_CACHE_GB
--perf	off	Print frame timing (fps, render / encode / between ms, frame size) every few seconds while the view moves. Also VISAGE_PERF=1
--gpu MODE	auto	Which GPU renders: auto prefers the discrete GPU on a Windows laptop with hybrid graphics; high / low force the discrete / integrated GPU; system leaves the OS default. Also VISAGE_GPU
--min-particles N	20 (the setup screens' choice)	Resolution: haloes with at least N dark-matter particles are kept, and galaxies from the stellar mass where 90% of centrals live in such haloes, worked out per snapshot (per redshift shell in a lightcone)
--min-halo-mass MSUN	—	A fixed halo mass floor (Msun), instead of --min-particles
--min-stellar-mass MSUN	—	A fixed stellar mass floor (Msun), instead of --min-particles
--max-halos N	100000	Downsample ceiling for haloes per snapshot

The mass cuts follow the simulation's resolution (its particle mass) rather than one number for every run. The particles a resolved halo needs (20, 50 or 100; default 20) are chosen under Resolved haloes on the SAGE26 and LightSAGE setup screens, and kept for every model opened afterwards.

Galaxies have no display cap — every galaxy passing the mass floor is loaded (all snapshots are preloaded, so there's no need to downsample for playback speed).

Par file fields used

ViSAGE reads the following fields from the .par file:

Field	Used for
OutputDir	Locating SAGE HDF5 galaxy output
FileNameGalaxies	Galaxy output file base name
FirstFile / LastFile	Range of tree files to read
SimulationDir	Directory containing the merger tree files (lhalo_binary or lhalo_hdf5)
TreeName	Base name of tree files (e.g. trees_063)
FileWithSnapList	Scale factor list file
LastSnapShotNr	Number of snapshots
Hubble_h	Unit conversion
BoxSize	Camera framing and zoom-to-box

Performance tuning

For interactive use on a laptop with miniMillennium:

visage --par input/millennium.par \
  --max-halos 30000 \
  --min-halo-mass 1e11 \
  --n-jobs 4

For cluster use with full data:

visage --par input/millennium.par \
  --max-halos 100000 \
  --n-jobs 16 \
  --port 8080