Celestia Forums

Hello All,
I wanted to create my own spacecraft model but i want the scale to be accurate relative to my planet.
When creating my 3ds model in max 9, what scale and units etc do I use for creating my model to make sure when I use in celestia its the correct scale?
Is a meter in max the same as a meter in celestia solor system?
also
I also wanted to know if its possibe to hide planets but have the spacecraft still show in celestia?
I have noticed that if i hide planets so hide all the spacecraft.

thanks
steve

A meter is a meter, if it's in a 3d program or celestia (it's a standard) it supposed to be the same because of being a standard.
Yes, it's the same.

Note that Celestia defines the radius of an object, not the length; so if you are making a spacecraft 100 metres long you need to give the object a radius of 50 metres in the .ssc file (if that is what you are using). This measurement assumes that the spacecraft is a sphere- so an irregular shaped craft may appear smaller if it does not fill the sphere completely (few spacecraft do).

I don't know how spacecraft modellers ensure that their models are the right size by using a radius declaration- would anyone care to elaborate?

Celestia does not directly use the units specified in the model.

For use in Celestia, the units you specify within the modeling program are whatever is convenient while modeling. The size drawn by Celestia is determined by the Radius that you specify in the object's SSC catalog file. Celestia normalizes the size to the largest dimension of the model and multiplies that by the Radius value.

When designing multiple models which are movable components of a larger assembly, I usually include identical boundary meshes in all of the pieces composed of invisible materials and outside the dimensions of the largest component. Then when they are defined with identical Radius values, they fit together perfectly. Otherwise one has to calculate individual Radius and relative position values, which sometimes can be difficult.

Hi
there was another part of question I didnt hear an opinion about.
"I also wanted to know if its possibe to hide planets but have the spacecraft still show in celestia?
I have noticed that if i hide planets so hide all the spacecraft."
perhaps i should restate question.
I was trying to replace planet mercury with a box but then hide the planet leaving only the box.
Can I do this?
So far I can create a box in additon to mercury and the box moves spins , rotates and acts just like Mercury.
I just wanted to hide the planet leaving only a box that behaves like Mercury.

You could say that I want Mercury to be a cube rather than sphere if that helps you understand me.
I imagine I would use the "Replace" in my addon .ssc but I dont have understanding how that works"

Any suggestions?
thanks for all the help so far.
steve

You can make an object invisible by creating an SSC containing an entry like the following. Class "invisible" was first available in Celestia v1.3.0.



When using Celestia from svn (i.e. v1.6 or later), you can manipulate an object's visiblity at runtime by using a CELX script like the following

or the equivalent


None of these should affect objects orbiting the invisible object.