High Precession Rates lead to bad orbit projection

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Topic author
MKruer
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High Precession Rates lead to bad orbit projection

Post #1by MKruer » 01.02.2005, 09:11

High Precession Rates for planets lead to bad orbit projection of moon/satellite

This is a possible bug.

For moons/satellites that are orbiting Planets with high Precession Rate, the orbits fail to display properly. Instead of orbit also adjusting for the Precession Rate, the orbit defaults to J2000 and stays like that. This creates a odd situation where the moon/satellite is in an orbit 90 degrees to the projected one.

Use the Following example to illustrate

Code: Select all

"Gigus" "Rylix"
{
   Texture "gigus.png"
   NightTexture "gigus_night.png"
   SpecularColor [ 0.6 0.6 0.4 ]
   SpecularPower 35.0
   HazeColor [ 0.6 0.6 0 ]   
   HazeDensity 0.3
   Radius 78641             
   Oblateness 0.1034       
   Albedo 0.51             
   RotationPeriod          7.8     
   Obliquity               91.1     
   EquatorAscendingNode    304.404     
   PrecessionRate          0.05364186 #degrees/day = 360/(Period*6711.1770)


   EllipticalOrbit
   {
      Period           18.3868
      SemiMajorAxis      7.401
   Eccentricity      0.0484
   Inclination       3.1252
   AscendingNode    100.556
   LongOfPericenter  14.7539
      MeanLongitude     34.404
   }
   
Rings
   {
      Inner  157810
   Outer  183210
   Texture "gigus_rings.png"
   }

}

 
#####   S/2113 G14   #####                                                                                    
"S/2113 G14" "Rylix/Gigus"                                                                        
{                                                                                          
   Texture       "default.*"                                                                                 
   Albedo       0.50      
   Radius       22.50                                                                                       
   Mass         2.44E+17                                                                                 
   Density      5.12                                                                                       
#   RotationPeriod    0.00                                                                                       
#   Obliquity      0.00                                                                                       
                                                                                          
   EllipticalOrbit                                                                                       
   {                                                                                       
      Period       0.00060671                                                                              
      SemiMajorAxis    215213.262                                                                        
      Eccentricity    0.104                                                         
      Inclination    15.13                                                                  
#      AscendingNode    -                                                                                    
   }                                                                                    
}

Michael Kilderry
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Location: London, UK

Post #2by Michael Kilderry » 02.02.2005, 05:49

This is probably a bit off-topic, but is the Rylix System still available? I saw it near the beginning of the Celestia Addons board and thought it looked interesting, but the link there didn't work.

Michael Kilderry :)
My shatters.net posting milestones:

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- Michael

Topic author
MKruer
Posts: 501
Joined: 18.09.2002
With us: 22 years 2 months

Post #3by MKruer » 02.02.2005, 07:38

Michael Kilderry wrote:This is probably a bit off-topic, but is the Rylix System still available? I saw it near the beginning of the Celestia Addons board and thought it looked interesting, but the link there didn't work.

Michael Kilderry :)


Short Answer:
No!

Long Answer:
I have been working on another project (shameless plug http://vegastrike.sourceforge.net) and have not had time to continue to develop the Rylix system. I am now getting back into developing the Rylix System, so you can expect a re-release sometime in the future.

Michael Kilderry
Posts: 499
Joined: 11.10.2004
With us: 20 years 1 month
Location: London, UK

Post #4by Michael Kilderry » 02.02.2005, 08:24

Sounds great. :D

Michael Kilderry :)
My shatters.net posting milestones:



First post - 11th October 2004

100th post - 11th November 2004

200th post - 23rd January 2005

300th post - 21st February 2005

400th post - 23rd July 2005



First addon: The Lera Solar System



- Michael

Topic author
MKruer
Posts: 501
Joined: 18.09.2002
With us: 22 years 2 months

Post #5by MKruer » 02.02.2005, 18:43

I don?€™t know if this is an error on my part, but isn?€™t the inclination of the moon, based upon the equatorial axis of the planet? If it is, then there is another bug, because the if the inclination of the moon is set to 0, it does not match up to the equatorial axis of the planet.

Topic author
MKruer
Posts: 501
Joined: 18.09.2002
With us: 22 years 2 months

Post #6by MKruer » 07.02.2005, 17:49

MKruer wrote:I don?€™t know if this is an error on my part, but isn?€™t the inclination of the moon, based upon the equatorial axis of the planet? If it is, then there is another bug, because the if the inclination of the moon is set to 0, it does not match up to the equatorial axis of the planet.


After reviewing my data, this error was on my part. However the Precession issue still exists

chris
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Post #7by chris » 11.02.2005, 16:52

MKruer wrote:I don?€™t know if this is an error on my part, but isn?€™t the inclination of the moon, based upon the equatorial axis of the planet? If it is, then there is another bug, because the if the inclination of the moon is set to 0, it does not match up to the equatorial axis of the planet.


Yes, the orbit of a moon is relative to the equatorial plane of the planet it orbits. I've promised an option to use different reference planes for moon orbits, but still haven't gotten around to implementing anything. I'll look at the precession rate bug . . .

--Chris

Topic author
MKruer
Posts: 501
Joined: 18.09.2002
With us: 22 years 2 months

Post #8by MKruer » 16.12.2005, 19:06

Bump: Has this bug been fixed in the latest prereleases?
Update: No this has not been fixed as of yet. Adding to the 1.4prev9 bug report thread.

This is a top view of Gigus, and the moons rotating around it. Notice how the moons orbit around the equator, but because of the high precession rate, the rendered orbit paths are off, and static to the J2000 start date.
Image


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