Optimizing the Milky Way Atlas
Optimizing the Milky Way Atlas
While technology is quickly catching up with the graphics power our Atlas demands, some people still find that the Atlas runs sluggishly on their computers. There are a few things you can do to reduce your computer's strain.
Threshold the Stars
The most common culprits in the Milky Way Atlas are the stars. We distribute a star catalog with more than 100,000 stars, mostly from Hipparcos and a few from the Gliese Catalog. Many computers cannot handle all of these stars with their points and textures. Using the Partiview command thresh, you can remove many of the stars from view, improving the performance.
We have placed many preset threshold statements for the stars in the mw.cf file. Some threshold distance, others the star's color. One threshold useful for eliminating most of the stars without altering the night sky view is a threshold on the stars' brightness, called the apparent magnitude.
The system of stellar magnitudes has its roots in ancient times. The scale is such that the brighter the object is, the smaller its apparent magnitude is. The brightest object in the sky, the Sun, has a magnitude of -26; the moon's is -12. The brightest star in the sky other than the Sun, Sirius, has a magnitude of -1. Our eyes can see to about +6.5 magnitude, so thresholding the stars that are dimmer than this will preserve the night sky while cutting out many of the stars.
We have set up a threshold statement in the mw.cf file that removes all stars over 7.5 apparent magnitude. To activate it, type
see m75at Partiview's Command Line. Alternatively, you could enter the command by typing thresh appmag < 7.5. This leaves you with about 25,000 stars and, we hope, improved performance. If you are still having troubles, though, please read on.
Turning Points or Polygons Off
If thresholding the stars did not improve your flight speed, then try turning off a few other things.
Try turning off the points on the stars. Compare that with turning off their polygons to see what works best. Visually, both of these have drawbacks. Viewing stars as points leaves you without proper depth cuing, making it difficult to judge what is near and what is far. Conversely, turning the polygons on and the points off leaves the stars rather fuzzy.
All-Sky Surveys
Another possible drain on your graphics resources is the all-sky images. While they add beauty, they also tax your hardworking computer. Turning them off may make your computer a whole lot faster.
Save Your Changes
Once you have the settings configured for your system, open the mw.cf file in a text editor and alter the file to suit the improved custom configuration.
© 2002-2005 American Museum of Natural HistoryLast Modified: 2007-12-19 by Brian Abbott