Posts by NASA_SimGuy

by NASA_SimGuy
19.05.2020, 13:44
Forum: Locations
Topic: Why is Period needed for Kepler inputs
Replies: 1
Views: 139

Why is Period needed for Kepler inputs

Why is the orbital period needed for Kepler inputs? Our simulation determines the orbital speed around the moon as a function of radius from the moon. I comented out the period and the vehicle did not initialize properly. Is there a way to have Celestia's velocity use the radius from the moon? Ellip...
by NASA_SimGuy
12.05.2020, 13:15
Forum: Utilities
Topic: High Fidelity Gravity Models
Replies: 2
Views: 157

High Fidelity Gravity Models

Anyone know if there are high fidelity gravity models for objects like Earth's Moon in Celestia? We have a few models in our simulations but I would like to cross check them with Celestia. We are using LP100 and GRAIL.
by NASA_SimGuy
23.03.2020, 16:39
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

Re: reading my ECEF pos/vel and quaternions

I tried "onetwothree"s suggestion by swapping around my quaternion's eigen values. such as: x y z w -> x -z y w I was never able to get the proper rotation. The Captain said not to use Orientation with BodyFrame. I want to try to insert my 3D model's rotation (such as the Orientation ) int...
by NASA_SimGuy
23.03.2020, 12:16
Forum: Scripting
Topic: Reading a file in a Lua script
Replies: 11
Views: 431

Reading a file in a Lua script

The 'wait(0)' fixed my problem. I also modified the celestia.cfg so I don't get the nag message.

I am testing the attachment process with my nag message.
Thanks again for you help.
by NASA_SimGuy
20.03.2020, 19:03
Forum: Scripting
Topic: Reading a file in a Lua script
Replies: 11
Views: 431

Reading a file in a Lua script

Sorry, onetwothree. My celestia:requestsystemaccess statement was ambiguous. I placed the celestia:requestsystemaccess statement at the top of my script. I still am getting the same missing io error. There was no error on the line where I added celestia:requestsystemaccess. Thanks Seldon, for the zi...
by NASA_SimGuy
20.03.2020, 18:19
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

Re: reading my ECEF pos/vel and quaternions

That sounds like it might work. I tried different combinations of swapping axis (and negative signs) but I can't get my model to move in the direction of the velocity vector. I figure there is around 16 different combinations of rotations. My 3D model has the +x pointing in the direction of the velo...
by NASA_SimGuy
20.03.2020, 18:07
Forum: Scripting
Topic: Reading a file in a Lua script
Replies: 11
Views: 431

Re: Reading a file in a Lua script

I moved "C:\Program Files (x86)\Celestia" to MyDocuments and I still get the io error. I added celestia:requestsystemaccess() at the top but I get the error. I right clicked on the Celestia Desktop short cut and ran it "As Administrator" but I get the error. Did you have to add t...
by NASA_SimGuy
20.03.2020, 16:42
Forum: Scripting
Topic: Reading a file in a Lua script
Replies: 11
Views: 431

Re: Reading a file in a Lua script

my lua5.1.dll is 236kbytes. I am using Celetstia 1.6.1. I tried celestia:requestsystemaccess() but I received the same io error. I wasn't aware that any version is more recent than 1.6.1. Is there an installer of do I have to build it? Maybe my quaternions will work with the new verison 1.7. I went ...
by NASA_SimGuy
20.03.2020, 15:23
Forum: Scripting
Topic: Reading a file in a Lua script
Replies: 11
Views: 431

Reading a file in a Lua script

I want to read a large events file in my.celx script. I will use this to print event text to the screen during a "spacecraft" trajectory flight. I noticed that the io.open will not work because the io.dll is not included in Celestia. Is there a "work around" to getting my large t...
by NASA_SimGuy
20.03.2020, 13:25
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

pos/vel and quaternions

One of Selden's comments back in 2008 stated: "values are the 4 components of the object's orientation specified as a quaternion relative to the object's BodyFrame." My assumptions are that the necessary quaternion is a rotation from the inertial to body coordinate frame. My quat output is...
by NASA_SimGuy
19.03.2020, 18:37
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

pos/vel and quaternions

Seldon: I been reading on rotation and orientation all day because my quaternions are still not working. I found your suggested *.ssc many moons ago relating to Frames (see below). Why did you suggest OrbitFrame and BodyFrame in the same object? Does order of Frames matter in an ssc file? Were your ...
by NASA_SimGuy
18.03.2020, 19:28
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

Re: reading my ECEF pos/vel and quaternions

Thanks Seldon, I understand more about the Celestia inputs from your response. I now have my SLS rocket starting at Kennedy. Now, my orientation is not pointing towards my velocity vector. I started to write a velocity fudge at the commented out portion of the bottom but I really want to get my quat...
by NASA_SimGuy
17.03.2020, 15:55
Forum: Celestia Users
Topic: reading my ECEF pos/vel and quaternions
Replies: 12
Views: 402

reading my ECEF pos/vel and quaternions

I have ECEF position and ECEF velocity in the BET files referenced below. They are in kilometers and kilometers/sec as documented. I also have the quaternions for this trajectory as inertial to body. I setup my *.ssc file and started Celestia but the SLS_PB vFS trajectory does not start out at Kenne...
by NASA_SimGuy
14.11.2018, 18:17
Forum: Ideas & News
Topic: Interstellar routes? Saving markers?
Replies: 4
Views: 2879

Re: Interstellar routes? Saving markers?

John71 said: The easiest is to replace the file "asterisms.dat" with one which draws your routes instead of constellations. What text do I place in the asterisms.dat file to draw lines? Is this documented somewhere? I need to draw 3D lines as I receive UDP packets with my trajectory state ...
by NASA_SimGuy
29.10.2018, 11:53
Forum: Scripting
Topic: Adding a spacecraft dynamically in Lua script
Replies: 10
Views: 2706

Re: Adding a spacecraft dynamically in Lua script

The y and Z might be swapped because Celestia uses a "Wandering frame" to reduce the changes of singularities when propagating.
by NASA_SimGuy
26.10.2018, 14:04
Forum: Scripting
Topic: Adding a spacecraft dynamically in Lua script
Replies: 10
Views: 2706

Scripted Positions/Quaternions

I want to learn about Celestia frames. Please don't just point me to the Wiki. Gironde wrote that I will have to swap y and z coordinates. Why is this? What coordinate system has huge z values w.r.t. x and y? I thought universal, ecliptic and universal were all the same. I see where I can get the ob...
by NASA_SimGuy
22.10.2018, 15:49
Forum: Scripting
Topic: Adding a spacecraft dynamically in Lua script
Replies: 10
Views: 2706

Adding a spacecraft dynamically in Lua script

I now have an SLS vehicle with a ScriptedPosition and Rotation :smile: I need to use my ScriptedPosition Function "vFSPos" to set the SLS position. I can hard code the orbit:position(tjd)'s returned position to a float but I want to make calls like celestia:find("Earth") and use ...
by NASA_SimGuy
19.10.2018, 19:10
Forum: Scripting
Topic: Adding a spacecraft dynamically in Lua script
Replies: 10
Views: 2706

Not allowed to Navigate to Scripted Spacecraft

Thanks selden, I created an SLS.ssc file defined below but I cannot Navigation|"Select Object" like I do for the ISS. I know the 3D model works because I substituted it in the ISS.scc and it showed up. I would have added the files if I knew how to attach a file to the forum. Thoughts? # Sp...
by NASA_SimGuy
18.10.2018, 18:20
Forum: Scripting
Topic: Adding a spacecraft dynamically in Lua script
Replies: 10
Views: 2706

Adding a spacecraft dynamically in Lua script

I have a working Lua script but I want to add a new spacecraft to the scene. I want to add several spacecrafts and there states using the accessors similar to celestia:newframe("universal") After adding the spacecraft to the scene, I want to update the states from inside the Lua script. Is...

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