Celestia Forums

Having been very impressed with Celestia, I've started a project for it. Being a 3d modeller by trade, I'll be supplying 3D models to go with my add ons. But I have an idiot newbie question:

The data I have for the stuff I'm doing lists epoch year, epoch day and epoch revolution, but in the .ssc files, I only see an 'epoch' value. How does this relate to the previous three I listed?

And what are radius and albedo? I presume radius is some visibility value?

The value for epoch is a Julian Date. There's a converter and a decent explanation here:

http://aa.usno.navy.mil/data/docs/JulianDate.html

Radius is a scaling parameter. For spheroid planets, it's the equatorial radius. For an irregular objects like a spacecraft or asteroid, it's half the length of the longest axis of the object. The radius is always specified in units of kilometers.

Albedo is the fraction of visible light reflected by an object. It ranges from 0.0 for a completely absorbtive (black) object to 1.0 for a perfect reflector. It's actually adjusted for the geometry of an object, so spacecraft have fairly low albedos because they reflect significantly less radiation than their bounding sphere would.

--Chris

I too have been seriously wanting to make some 3ds models
for Celestia. It's tough because I expend an awful lot of energy
to make a living, like everyone else I guess.

But I really would like to model SoHo, because it's a big baby and
it has a very interesting orbit between earth and the sun.

If anyone has any good reference web-sites for SoHo let me know
(besides the many I have already visited).

Vic

Thanks for the info. More details on the project once I get a good working copy of my .ssc file sorted out :)

I've just started playing around with the .cel files and I was wondering if anyone with the rare commoditty of free time could give me some advice, such as :
How do you use them in the program without modifying the file "start.cel" ?
How do you use the sychronous command ? I've tried it, and sometimes it works fine, sometimes it decides to zoom out to over 200 A.U.
When using the "goto" command I first get a smooth zoom in then suddenly the selected object appears out of nowhere at the specified distance - can't I make it zoom in in the usual smooth style the program does automatically ?
Is there a way of rotating your view of the selected object ?
And any other hints and tips would be welcomed too....

Also if anyone knows where I could get hold of a half-decent (i.e. moron proof) cheap (preferably free, if possible) piece of software for making 3D models comptable with Celestia I would be in their eternal debt, and would possibly consider worshiping them as a God.

3D Canvas can make 3D models and export them to .3ds format. It's $30 I think from http://www.amabilis.com .....

Try a program called openFX. Its free and opensource

http://www.openfx.org/news/index.php

In the windows preview version of 1.2.4 there is a "load file" command to load cel files.

The goto sometimes jumps because the program may be pausing while loading a texture for that planet

to rotate you view use the mouse and the buttons.

Thanks for the help and suggestions. I tried downloading OpenFX, it ran once (with an error in the animator, but I liked the designer screen), but crashed when I tried it a second time. In fact I got a message telling me my computer had recovered from a serious error, so I won't be trying THAT program again anytime soon. The search continues.....

I did not have any probs with OpenFX-1.0 under Windows ME, even after playing for quite a while with it (until I got bored and trashed it again;-))

Fridger

It's propably just another undocumented, unpublicised, unusual error with Windows XP, then. Damn Microsoft.... never mind.

This program only crashes for me when I exit. They are porting it to linux right now and hopefully newer versions will come out after that. Now that blender is dead this is probably the best free 3d modeller/animator available

Shame about Blender. I don't suppose there's anywhere on the net I can still get a copy ? (that would be asking too much, wouldn't it ?) I will try the smallest version of OpenFX, if that doesn't work I'll just give up.
Back on the subject of .cel files, how do I use the synchronous command (any parameters needed ?), and is there a way of rotating the planets automatically ?