Houdini models - bug or artifact?

[rjcraig]

In trying to familiarize myself in one fell swoop with models and textures and .ssc files, I've done something a bit odd: creating a hollowed out asteroid "colony" and trying to set it in an orbit with Sol and Alpha Centauri A as the foci. The model has some color display problems that I haven't figured out yet (any color I try to use comes out black) and I'm not quite sure how to orient the orbit exactly (through trial and error I've managed to come within 0.0883 ly of ALF Cen A at Sol aphelion, but can't seem to get it closer).

Here are the contents of the ssc file I have in the extras folder:

"Arkimedes" "Sol"
{
Class "spacecraft"
Mesh "arkimedes.3ds" # based on Bacchus
Texture "asteroid.jpg"
Color [ 0.52 0.47 0.42 ]
Radius 50

EllipticalOrbit
{
Period 600.0
SemiMajorAxis 139000.0
Eccentricity 0.99999999
Inclination 95.7
AscendingNode 64.85
ArgOfPericenter 44.0
}
}

Ignoring for a moment the unrealistic aspects of this (eg. at Sol perihelion the object is moving at several times c), how should I go about calculating the values for the orbit I want?

More important (and the real subject of this post), at 2014 Nov 28 14:25:11 JST (05:25:11 UTC), the model disappears from view and remains invisible until 2585 02 07 18:34:49 UTC. Since this "now you see it, now you don't" phenomenon repeats every orbit, I'm wondering if it has to do with the distance of the object from Sol.

I've searched through the forums for mention of similar problems but haven't found anything. Any ideas or suggestions? (Other than "find something else to worry over")

Ron

Celestia 1.3.1-1
Mac OS 10.3.1 / PowerBook G4 / 64 MB ATI / 1280 x 854 32-bit LCD

[granthutchison]

Celestia doesn't go looking for objects that are farther from their parent star than the nearby stars ... so by putting your object in an orbit that passes beyond Alpha Cen, you're making it drop over Celestia's rendering horizon, which I imagine is why it's disappearing for part of its orbit.

Grant

[rjcraig]

Thanks, Grant.

I figured it was something like that.

Would it be possible to model this with an XYZ file, then? Or will this run into the same limit? (A problem eventually for simulating the Voyager probes, no?)

Ron

[JackHiggins]

Would it be possible to model this with an XYZ file, then? Or will this run into the same limit? (A problem eventually for simulating the Voyager probes, no?)

Yup, same limit for xyz files, but the voyagers xyz's end in 2040, WELL before the rendering limit would start to affect them.

[rjcraig]

Yup, same limit for xyz files, but the voyagers xyz's end in 2040, WELL before the rendering limit would start to affect them.

Thanks for the reply, Jack. Makes sense that it holds true in all cases.

This is a completely different topic, but do you know if the relative motions of stars will ever be implemented? (Is there enough information available for all the stars in the catalogue?) Maybe realistic revolution around the galactic core is a bit much to hope for, but a better representation of the orbits of binary/multiple systems would be nice.

--Ron

[maxim]

There had been some discussion om proper motion in threats around here.
See for example http://216.231.48.101/forum/viewtopic.php?t=4727&start=0. Perhaps you can contribute.

maxim