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Removed outdated description of stars.dat binary file format from README; 

added a link to the catalog files section of the Celestia WikiBook instead.
ver1_6_1
Chris Laurel 2008-07-13 21:45:31 +00:00
parent 8e729f9a8f
commit ace29126b0
1 changed files with 23 additions and 22 deletions
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README
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@ -213,11 +213,16 @@ own start-up settings. Simply open the file "start.cel" in a plain text
editor and follow the in-file instructions. Also, view the celestia.cfg file editor and follow the in-file instructions. Also, view the celestia.cfg file
in a plain text editor to see additional settings. in a plain text editor to see additional settings.
Celestia allows you to create an entirely fictional universe, by modifying its Celestia allows you to easily add real, hypothetical, or fictional objects
solarsys.ssc, stars.dat, and hdnames.dat files. The easiest file to modify is by creating new catalog files. It is *not* recommended that you alter the
the solar system catalog (solarsys.ssc), since it's a plain text file and the built-in data files; nearly all desired modifications and additions can be
format is very text-editor friendly. It's also quite verbose, but that's not made by placing new catalog files in Celestia's extras folders. There are three
a problem yet. types of catalog files:
- ssc (solar system catalog: planets, moons, spacecraft, etc.)
- stc (star catalog)
- dsc (deep sky catalog: galaxies, star clusters, and nebulae)
All three types of catalog file are text files that can be updated with your
favorite text editing program.
The units used for the solar system data may not be obvious. All angle fields The units used for the solar system data may not be obvious. All angle fields
in the catalog are in degrees. For planets, the period is specified in earth in the catalog are in degrees. For planets, the period is specified in earth
@ -265,25 +270,21 @@ fractal displacement map likenesses of asteroids and small moons. 3DS meshes
are normalized to fit within a unit cube -- the Radius field determines how are normalized to fit within a unit cube -- the Radius field determines how
big they appear within Celestia. big they appear within Celestia.
The stars.dat file is a binary database of stars, processed from the 50+ meg Most of the stars in Celestia are defined in the binary file stars.dat.
HIPPARCOS data set. The first four bytes are an integer (int) value The binary format is used instead of a text stc file because it's more
containing the number of stars in the database. Following that are a bunch of compact and faster to load; the size and speed advantages of a binary file
records of this form: are significant with the over 100,000 stars in the Celestia. Stars.dat was
4 byte int : catalog number generated from the HIPPARCOS data set. Revisions and additions to the
4 byte float : right ascension HIPPARCOS data set appear in the stc files revised.stc, nearstars.stc,
4 byte float : declination visbins.stc (visual binary stars), and spectbins.stc (spectroscopic binary
4 byte float : parallax stars.)
2 byte int : apparent magnitude
2 byte int : stellar class
1 byte : parallax error
RA, declination, and parallax are converted to x, y, z coordinates, and There are two very helpful resources with much more detailed information
apparent magnitude is converted to absolute magnitude when the database is about creating add-ons for Celestia:
read. Selden's "Introduction to Celestia Add-ons" web page:
For more detailed information about creating add-ons for Celestia, please
visit Selden's "Introduction to Celestia Add-ons" web page at:
http://www.lns.cornell.edu/~seb/celestia/addon-intro.html http://www.lns.cornell.edu/~seb/celestia/addon-intro.html
The catalog file reference on the Celestia Wikibook:
http://en.wikibooks.org/wiki/Celestia/Catalog_File_Reference
CELESTIA RESOURCES CELESTIA RESOURCES