Celestia Forums

As posted in http://www.shatters.net/forum/viewtopic.php?f=2&t=10779, please consider allowing the use of 3DConnexion (or others) space mice.

Thank you,
Tony

Hey,

I want to pick up a thread which has been posted some months ago.
It's a post from Guckytos mentioning the topic "Ground Tracking of satellites", that can be found in this thread:

viewtopic.php?f=2&t=5661&p=108256&hilit=visual+tracking&sid=30c8effa8a85132c7e673f4c1c8354c9#p108256

Guckytos wrote:....

You probably all know those big wall screens from NASA operations center, where they show on a flat earth those sinusoidal tracks of (mostly) the ISS and space shuttle missions.

Now couldn't we add a similar feature to Celestia? I certainly know that we wouldn't see a sinusoidal track on a ball, but we could show a point on earth, where the orbiting object is perpendicular above.
This point could then be resampled every few seconds and drawn a new one, or directly a line?
Then in an option menu, you could choose how many orbits you want to be shown.

...

What do you think about that?

Regards,
Guckytos

Has there been any progress concerning tracking of satellites on the ground?
Is it possible to visualize an orbit which is calculated by a scriptedOrbit-function?

Thanks,
Stuffer

Stuffer wrote:Hey,

I want to pick up a thread which has been posted some months ago.
It's a post from Guckytos mentioning the topic "Ground Tracking of satellites", that can be found in this thread:

viewtopic.php?f=2&t=5661&p=108256&hilit=visual+tracking&sid=30c8effa8a85132c7e673f4c1c8354c9#p108256
...
Has there been any progress concerning tracking of satellites on the ground?

See viewtopic.php?f=6&t=13047&
and viewtopic.php?f=7&t=13060&
It's expeced to be in v1.7.

Is it possible to visualize an orbit which is calculated by a scriptedOrbit-function?

Only if it's a closed orbit and its period is specified in the Lua function. See http://en.wikibooks.org/wiki/Celestia/T ... iptedOrbit

Having the ability to orient and change positions of models in real time would be useful. Instead of having to go back and forth to the SSC file you could just click on a object and adjust it's orientation and position to where you want it then lock it into place.

Stuffer wrote:Hey,

I want to pick up a thread which has been posted some months ago.
It's a post from Guckytos mentioning the topic "Ground Tracking of satellites", that can be found in this thread:

viewtopic.php?f=2&t=5661&p=108256&hilit=visual+tracking&sid=30c8effa8a85132c7e673f4c1c8354c9#p108256

Guckytos wrote:....

You probably all know those big wall screens from NASA operations center, where they show on a flat earth those sinusoidal tracks of (mostly) the ISS and space shuttle missions.

Now couldn't we add a similar feature to Celestia? I certainly know that we wouldn't see a sinusoidal track on a ball, but we could show a point on earth, where the orbiting object is perpendicular above.
This point could then be resampled every few seconds and drawn a new one, or directly a line?
Then in an option menu, you could choose how many orbits you want to be shown.

...

What do you think about that?

Regards,
Guckytos

Has there been any progress concerning tracking of satellites on the ground?
Is it possible to visualize an orbit which is calculated by a scriptedOrbit-function?

Thanks,
Stuffer

I've done some work on this, but it won't make it into the 1.6.0 release. Soon afterward, however...

See this example:

http://www.youtube.com/watch?v=R20d8sJae4E

--Chris

Reiko wrote:Having the ability to orient and change positions of models in real time would be useful. Instead of having to go back and forth to the SSC file you could just click on a object and adjust it's orientation and position to where you want it then lock it into place.

That's already possible for the orientation.
Please take a look at http://www.lepp.cornell.edu/~seb/celest ... d.html#6.0
It describes how to do it with a DSC object, but a similar technique works for SSC objects.

selden wrote:

Reiko wrote:Having the ability to orient and change positions of models in real time would be useful. Instead of having to go back and forth to the SSC file you could just click on a object and adjust it's orientation and position to where you want it then lock it into place.

That's already possible for the orientation.
Please take a look at http://www.lepp.cornell.edu/~seb/celest ... d.html#6.0
It describes how to do it with a DSC object, but a similar technique works for SSC objects.

Does it also work for stc and other objects?
Are there exceptions?

duds26 wrote:Does it also work for stc and other objects?
Are there exceptions?

The realtime orientation command only works for SSC and DSC objects, not for STC objects. A better permanent solution is to change the model itself or change its rotation parameters in its catalog file.

Hey,

Since one could activate displaying of body axes and sun and velocity vectors, is it possible to display random vectors?
Can those vectors' legth be controlled manually?

What I intend to do with that is displaying which ground station a s/c is currently connected/ sending data to. It would be sufficient if this was just a simple line or sth. like that. And when it gets out of the sation's range the vector should aim to the next station or just be gone if no station is available.
Do I have to implement such a thing with an own obeject's file?

Thanks in advance
Stuffer

This sounds like a cool idea, and it seems to me that it should be quite easy to do if you have access to the code.

In short...
Find the code that calculates and displays the sun direction reference frame arrow.
Create a version which substitutes an arbitrary or selected target for the Sun.
Set the length of the arrow to the distance between the satellite and the selected target (you'll probably need to calculate this, but thee will be code somewhere which you'll be able to scavenge for this purpose).

How and when you call this version will depend on what you want to achieve.

CC

A slightly crude version of such an arrow can be done without modifying Celestia.
I call it crude because the arrow's entire size changes. It'd be nice if only its length changed.
(There are ways that can be faked, too.)

The things you'd need to do are
1. provide a model of an arrow
2. write ScriptedOrbit and ScriptedRotation Lua functions for the arrow which
a. determine the distance from object a to object b.
b. determine the direction from object a toward object b.
c. set the radius of the arrow proportional the the value of interest (the function setradius() is available in v1.5.1.)
d. return position (ScriptedOrbit) and orientation (ScriptedRotation) values to specify the arrow's position and pointing direction.

Chuft-Captain and Selden, thanks for your answers.

I'm trying to realize Selden's suggestion first because I'd rather not change Celestia's source code for now. But of course this seems to be the more appropriate solution. Anyway....

I observed a new problem though:
I'm reading the position and rotation values from a socket and write them into a global table from where I call those values in the ScriptedOrbit functions.
Since I want to have the arrow extremely near to the s/c for now I simply take the same coordinates for both "spacecrafts". But they aren't displayed at the same position. Actually if I'm looking a closer look at one of them I can't see the other one. But I can't see where this could from since they are supposed to read the same values.

Of course it takes Celestia some time to call the one position function and then the other so the coordinate values have changed but is that the only reason that they are this far from each other? Even if I have a very high orbitperiod they are quite far away from each other.
Can I use the same ScriptedOrbit for two s/c's? would this help?
Thanks


Edit: in hte axisarrows.cpp I found a part:
/****** BodyToBodyDirectionArrow implementation ******/

Most likely this is what I should use in case but I'm not sure if I could handle this the right way.
The SunVector seems to be an appropriate example but as said I'm not sure if I can figure out when it gets called and which values are needed to provide with the function calls.

You are supposed to be able to use the same Scripted functions for multiple objects. Of course, it's also possible to write them so they assume things which are only true for specific objects. If the code is sufficiently general, then they should work.


I now have a vague recollection of there being a discussion about BodyToBody vectors. I don't recall the details, though. I suspect it's used for the RMB menu item Show Sun Direction. ChrisL or Vincent are likely to remember more about it.

Thanks Selden,

You've been right, I am able to use the same Sripted function several times when having several models in the same add-on folder. But still their positions don't match and I can't see why.

Do they orbit the same body?

The coordinates returned by the ScriptedOrbit function are in the object's current OrbitFrame. If that's different, they'll be in different positions.

Selden,

you were right again. They are orbiting the same body, but I had a reference frame for only one of them.
I wonder how you can have all those things in your mind .

Thanks a lot.

Stuffer wrote:I wonder how you can have all those things in your mind .

Thanks a lot.

You're quite welcome.

I tend to remember things when I've done them a thousand times.
(My Hale Telescope addon has grown to more than a thousand components.)

selden wrote:

Reiko wrote:Having the ability to orient and change positions of models in real time would be useful. Instead of having to go back and forth to the SSC file you could just click on a object and adjust it's orientation and position to where you want it then lock it into place.

That's already possible for the orientation.
Please take a look at http://www.lepp.cornell.edu/~seb/celest ... d.html#6.0
It describes how to do it with a DSC object, but a similar technique works for SSC objects.

Thank you, works like a charm.

One thing I noticed though. When reorienting an object it doesn't change the axis orientation.

Before





And after



As a result I can no longer have the object rotate along it's longest axis or else it will tumble at an odd angle.

Request for adding spiral orbits.

They could be used for objects falling onto/into other objects.
(Simulation of attraction to a point.)

e.g. the orbit of objects falling into a black hole.
the orbit of a spaceship or meteor crashing on the moon or other planet.

Wikipedia link: https://en.wikipedia.org/wiki/Spiral

Enhance info-url
Multiple Info-url possible.
This would enhance celestia a lot.

For a lot of bodies there are a lot of multiple sources with good information.
Now most url's have a link to the eight planets website: http://www.nineplanets.org/
But many would like a link to other sources than this website e.g. wikipedia, NASA and ESA-site about the subject.

Please don't make it possible to set any visible text and adding and assigning an actual url to it.
Then we never see what the url actually is, this kind of thing is a security disaster.