Digistar II VLA file format

Written by Paul Bourke
June 2002


A Digistar II VLA file is supported by a number of utilities supplied with the Digistar system, it facilitates the migration of geometry from third party applications to the Digistar planetarium dome projection. The files are text (ascii) only, they consist of a header section followed by the coordinate information. The text in a VLA file is case insensitive. A line starting with a semicolon ";" is taken to be a comment, these may appear anywhere and the comment continues until the end of the line.

Header

The header consists of a number of keywords indicating different header information, each line is of the following form.

   set keyword data_for_this_keyword

The keywords can be from the following list, they can appear in any order, not all are required eg: author, and some can occur many times, eg: comments.

Coordinate data

Each line contains one geometric element consisting of the following fields.

   datatype  x  y  z  intensity

The datatype can be one of the following, it is based upon the notion of moving a beam in either an on or off state in a similar way to pen plotters for example.

Cube example

The following is a simple example of a unit cube sitting on the x-y plane. Note that this could be made much more efficient by reducing the number of "P" commands and drawing longer sequences of connected lines, this is an important consideration for more complicated models where the vector throughput may limit the datarate.

set comment cube.vla created by IVCON.
set intensity EXPLICIT
set parametric NON_PARAMETRIC
set filecontent LINES
set filetype NEW
set depthcue 0
set defaultdraw STELLAR
set coordsys RIGHT
set author IVCON
set site Buhl Planetarium
set library_id UNKNOWN
P -0.500000 -0.500000 1.000000 1.00
L 0.500000 -0.500000 1.000000 1.00
L 0.500000 0.500000 1.000000 1.00
L -0.500000 0.500000 1.000000 1.00
L -0.500000 -0.500000 1.000000 1.00
P 0.500000 -0.500000 0.000000 1.00
L -0.500000 -0.500000 0.000000 1.00
L -0.500000 0.500000 0.000000 1.00
L 0.500000 0.500000 0.000000 1.00
L 0.500000 -0.500000 0.000000 1.00
P -0.500000 -0.500000 0.000000 1.00
L -0.500000 -0.500000 1.000000 1.00
L -0.500000 0.500000 1.000000 1.00
L -0.500000 0.500000 0.000000 1.00
L -0.500000 -0.500000 0.000000 1.00
P 0.500000 -0.500000 1.000000 1.00
L 0.500000 -0.500000 0.000000 1.00
L 0.500000 0.500000 0.000000 1.00
L 0.500000 0.500000 1.000000 1.00
L 0.500000 -0.500000 1.000000 1.00
P -0.500000 -0.500000 0.000000 1.00
L 0.500000 -0.500000 0.000000 1.00
L 0.500000 -0.500000 1.000000 1.00
L -0.500000 -0.500000 1.000000 1.00
L -0.500000 -0.500000 0.000000 1.00
P -0.500000 0.500000 1.000000 1.00
L 0.500000 0.500000 1.000000 1.00
L 0.500000 0.500000 0.000000 1.00
L -0.500000 0.500000 0.000000 1.00
L -0.500000 0.500000 1.000000 1.00
From the Digistar technical overview

Evans & Sutherland's star projection system, Digistar II, is a real-time, computer graphics based system intended to entertain and educate large audiences. Show producers can create environments that completely immerse audiences in 3D real-time computer generated images. Digistar II is a special-purpose computer graphics system that can do everything a conventional planetarium system can do in addition to other advanced features. Besides simulating traditional planetarium objects, Digistar II generates new special effects, such as dynamic proper motion and travel through three-dimensional space.

Further examples

galaxy.vla.gz galaxy.gif
knot.vla.gz knot.gif
lorenz.vla.gz lorenz.gif
pulsar.vla.gz pulsar.gif
tritorus.vla.gz tritorus.gif
universe.vla.gz universe.gif