Celestia Forums

When I go to see stuff on the surface of planets (such as the Mars pathfinder or the Atlantis shuttle sitting on the launch pad in Florida), Celestia zooms way in toward the planet, an extreme close-up of the planet's texture fills the screen, then before I see the spacecraft model, the planet completely disappears and I see the thing that's supposedly on the planet surface floating out in space.

Is this just a limitation of my (marginal) system (16 MB Voodoo3 card), or is that just how Celestia does it, or is it something I can fix?

(Speaking of Atlantis, does anyone have some orbital numbers to put the "flying" model in orbit -- maybe near the ISS?)

There is at least two ways to explain what you see.

1- The model is placed at a wrong distance from the planet's center. It's standing UNDER the surface. This can be corrected in its .ssc file and is relatively easy to do. You must know the planet exact radius in km.

2- The model may be placed at the right distance and is standing ON the surface. However, you're watching the model from UNDER the ground, so the ground is disapearing. This is a feature, not a bug, and can't be changed.

In my opinion, all models placed on a planet surface should be associated with a tangent plane with some texture on it, because it's really dull to watch a model standing on a blurry ground (one color actually). If only Celestia was able to drop a shadow under the model, so we can feel it touching the ground, but I'm dreaming !

This is bringing me to an idea.

Is there any addons which put important objects, famous sites, on the earth, using 3ds models ? It could be nice, for example, to have addons which adds to the right location and orientation

1- The Eiffel tower,
2- The egyptian pyramids,
3- Pisa tower,
4- Some famous buildings in New York,
5- The Sagrada Familia in Barcelona,
6- the Machhu Pichhu in Peru,
7- Angkor Vat in Cambodgia,
8- Your car (or your dog, or, ..., wathever).
9- etc...

I know there's the Stonedge from Jestr, but anything else ?

Celestia approaches a selected object directly, so you will fly through the earth and see the object from inside the earth and underneath the object. If you right-click and drag you should see the earth surface come into view as you rotate around the target.

The easiest way to add your shuttle is to copy the ISS orbital parameters, but increase the orbit size slightly, i.e

"Atlantis" "Sol/Earth"
{
Class "spacecraft"
Mesh "Atlantis.3ds"
Radius 0.02

EllipticalOrbit {
Period 0.064176392
SemiMajorAxis 6767.04
Eccentricity 0.0016886
Inclination 51.5684
AscendingNode 343.1518
ArgOfPericenter 346.2476
MeanAnomaly 13.8216
Epoch 2452028.18381755
}
Orientation [90 0 0 1]
RotationOffset -90
Obliquity 30
}

You might need to change the "Atlantis.3ds" to whatever model you have, and here I've just added .04 to the SemiMajorAxis to put it above the ISS. Change the numbers and experiment with the effects.

Thanks for the Shuttle orbit. I thought about trying to duplicate the ISS one, but I didn't know which parameter(s) to tweak (or what magnitude to tweak them) to put it in a similar orbit but not right on top of it.

Maybe I was looking at the models from the wrong angle, but I don't think so. For some of them I was looking straight down on them then zooming out to see where they were on the planet then zooming back in to see the model again. Maybe they're sitting just under the surface (specifically, I'm trying to look at the shuttle sitting on the pad at Kennedy Space Center, and the Pathfinder/Rover models on Mars).

Which parameter would I adjust if I wanted to try moving them slightly above the surface (to make sure they weren't underneath it)?

Try changing the SemiMajorAxis number. It's a measure of the size of the elliptical orbit, like the radius is a measure of the size of a circle.

When the eccentricity is 0, the elliptical orbit becomes a perfect circle.

Is there any addons which put important objects, famous sites, on the earth, using 3ds models ? It could be nice, for example, to have addons which adds to the right location and orientation

Why stop at Earth? With the Pathfinder/MER missions, you could also add some close-up surface textures for Mars. Meaning, instead of just having Spirit sitting on a gray, featureless landscape, the photos from the mission could be used to make it actually show the terrain around it.

I've some shuttle models...I'm not sure if they all have sscs though. Check them out at my shuttle page.
http://www.berasan.com/celestia/bhshuttle.html
Regards...bh.
If they don't orbit correctly...pm me and I'll send you the code I'm using.