selden wrote:Cham wrote:selden wrote:Somewhere above I recall seeing a question of just how much slower Celestia is when it has a million stars. You can find that out by installing the data sets of 1 and 2 million stars derived from the Tycho Catalog and which are available on the MotherLode. With that many stars, it's reasonable to build a replacement binary star database in order to reduce the load time and to improve the runtime performance slightly.
Could you elaborate a bit more on this ? Can I make a binary version of my STC file while keeping it in the extra folder ? If so, how can I convert a STC file to a binary version ?
The file that comes with Celestia contains only the Hipparcos catalog of stars.
Yes, but including the new reduction by Floor van Leeuwen, 2007.
http://www.atlasoftheuniverse.com/hr.htmlThis means the best available parallaxes for the calculation of the required
absolute magnitudes!
Much of the respective work has been done already in Andrew's Perl script
buildstardb.pl that resides in src/tools/stardb. The script also contains a host of needed conversion routines, including magnitudes in various standardized filter bases and abs.mag <-> app.mag conversion using the parallaxes. Since MACs include a complete UNIX on the command-line level, I suppose Perl is also available by default.
In addition, there is the C++ code of binary <-> ascii converters (
startextdump,
makestardb ) for Celestia stars in the same directory.
Edit: But that material is partly outdated and/or not yet ported to the Eigen library etc:
[
The startextdump program converts a binary Celestia star database to an
easy to edit ASCII format. The command line is:
startextdump [options] [<input file> [<output file>]]
The resulting ASCII file can be used very easily also with
Maple, Mathematica. Perl can directlyl read in the binary stars.dat file, making another converter superfluous.
Of course, the reverse tool is also available in this directory in source-code form:
Makestardb converts an ASCII star database created by startextdump to a
binary star database readable by Celestia. Makestardb does not support the old star database format; the output files it produces are only usable with versions of Celestia
newer than 1.3.2.
The command line is:
makestardb [--spherical] [<input file> [<output file>]]
]
Edit:
A working binary version of
startextdump.exe for new stars may be found at ChrisL's familiar file archive:
http://www.celestiaproject.net/~claurel/celest ... xtdump.exeFridger