Celestia Forums

File can be found here:

http://www.geocities.com/doctorshnub/galaxies.txt

Rename TXT to DAT, remembering to back up your previous galaxies.dat before replacing it with this one.
I really hope that the galaxy brightness setting well enough to see the structure of the Local Supercluster, it's quite interesting how heterogenous it is.

The more adventurous might like to try this file:

http://www.geocities.com/doctorshnub/galaxies_and_clusters.txt

This contains the measured galaxy clusters out to 4 billion ly, rendered as "big galaxies". It doesn't really look right, of course, and it runs slow and overflows the z-buffer, but hey, it's just an experiment. It's interesting to see the supercluster structure, and it's nice to be able to fill the Universe with something...
It'd be really nice if someone wrote a shader to render a galaxy cluster, even if it worked like the galaxy one but instead of a cloud of diffuse blobs, it rendered little lenticular shapes.

More galaxies to come later...

Great Paul, I can't wait to test it! Unfortunately though I started having problems with your previous galaxies file; sometimes it freezes my pc on starting Celestia (OK, I admit, I run Win ME... ). And I don't see them anymore, only the labels. Maybe I'm overloading my system with too much big dds's, stars, asteroids, etc. etc.

Beautiful...Stunning....Ok this is just teasing me now....KILL THE DAMN 16k ly BOUNDRY DAMMIT!!!!! Ok Im better now...

Aha! A visibility boundary! That explains everything! I hope this can be solved.

It will eventually...Theres something new Ive noticed now with this updated galaxies.dat...Im using the biggest one btw...And its NOT due to the dat file its Celestia itself....The galaxies flicker due to overlapping renders...The milky way goes unaffected but several of the galaxies on the outer limits flicker a bit...And when approacing some of them they disappear when looking away from its galactic center...Like I said this is not because of Pauls dat file its just something not progammed into Celestia yet...well as far as I know...seems a logical assumption...

Paul wrote:File can be found here:

http://www.geocities.com/doctorshnub/galaxies.txt

Rename TXT to DAT, remembering to back up your previous galaxies.dat before replacing it with this one.
I really hope that the galaxy brightness setting well enough to see the structure of the Local Supercluster, it's quite interesting how heterogenous it is.

The more adventurous might like to try this file:

http://www.geocities.com/doctorshnub/galaxies_and_clusters.txt

This contains the measured galaxy clusters out to 4 billion ly, rendered as "big galaxies". It doesn't really look right, of course, and it runs slow and overflows the z-buffer, but hey, it's just an experiment. It's interesting to see the supercluster structure, and it's nice to be able to fill the Universe with something...
It'd be really nice if someone wrote a shader to render a galaxy cluster, even if it worked like the galaxy one but instead of a cloud of diffuse blobs, it rendered little lenticular shapes.

More galaxies to come later...

Thanks for generating this file . . . I'll have Celestia working properly with it before the next prerelease. There is a visibility limit that's causing some of the trouble, but I don't know if the flickering is related. Galaxies need to be selectable with the mouse, and there needs to be some sort of brightness control for them.

Paul, does the catalog from which you derived galaxies_and_clusters.txt contain orientations for the galaxies?

--Chris

Well, given that strongly increasing list of galaxies, I am glad that I recently introduced some efficient culling in the galaxy render list;-)

So people who want to play with Paul's new large list, make sure that you are using the most recent version of celestia 1.25preX!

I see virtually NO slowing down even with the list that includes the O(1k) galaxy clusters...

Bye Fridger

Both files work very well after all! It appears that if I start Celestia near Earth (with big dds and bumpmap), my poor little machine can't handle it if I also want to load a larger galaxy file, but when I start near the Sun there is no problem.

Beautiful...Stunning....Ok this is just teasing me now....KILL THE DAMN 16k ly BOUNDRY DAMMIT!!!!! Ok Im better now...

Actually, it would be extremely cool to be able to add stars and planets in other galaxies... is that what you were talking about? Oooh, I'd love to see the view from a planet in the middle of the Coma cluster...

Paul, does the catalog from which you derived galaxies_and_clusters.txt contain orientations for the galaxies?

It's Tully's Nearby Galaxies Catalogue:
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=VII/145
The orientations aren't complete, only inclination from face-on is specified. I hand-coded some orientations by hand for the more notable galaxies (like M51), but it's time-consuming and frankly there are other, more important problems:
1. Ellipticals don't seem to use orientation.
2. S0 (lenticular) galaxies are just rendered as normal spirals (there are a surpsisingly high proportion of these);
3. Almost all of the small (and plentiful!) irregular galaxies are bar-shaped. It'd be nice if the "Irr" type reflected this.
4. I haven't been able to work out exactly how Axis and Angle work. I know Axis is a vector, but that makes them hard to adjust by hand. Usually I just 'borrow' the Axis from M31 or the Milky Way, and try various values of Angle until it looks about right. Again, time-consuming.

What would be nice would be an Orientation [i,n] where i is the inclination from face-on, and n is the angle the axis makes with celestial North. This would make entering the orientations very easy.

I did a bit of work on galaxies . . .

I fixed the culling so that it works better outside the Milky Way--galaxies no longer blink in and out randomly. I also made galaxies pickable with the mouse, which makes navigating among them a lot easier. There's still the flickering problem and the dreaded 16,000 light year limit (applies only to stars, not galaxies). I think that the flickering arises from some sort of roundoff error--OpenGL seems to get fussy about rendering objects 300 million light years distance.

--Chris

Might be one of those things like breaking the sound barrier hehe...

Thanx again for your efforts Chris!