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Axes in FlightGear?

arno

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Does anybody know what axes FlightGear uses for its objects? I am working on reading the AC3D format, but it seems my object is mirrored.

In FS the axes are usually XZY, it seems now that FlightGear uses XZ-Y, but can anybody confirm that?
 

arno

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I have just put the AC3D reader and writer in the ModelConverterX development release, but I am still looking for clarification on these axes. I think the AC3D files I export now are not correct for FlightGear because the axes are different.
 

arno

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Hi Mike,

Not really, but the Wiki helped. I now found another page:

http://wiki.flightgear.org/Howto:_3D_Aircraft_Models

That seems to explain the coordinates used for aircraft. Although in the AC3D files I have found until now the Z is not up, the Y is up (like in FS). So I will do some more searching.
 

arno

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I just had a quick scan of it, it seems they have many systems indeed. Although I did not see a confirmation of what I found in the AC3D models, that looks like to be different again. I'll do some more reading.
 
I wonder why both FS and XP chose not to use the conventional aircradft axis system:

x +ve forward
y +ve starboard
z + ve downwards?
 
Both FlightGear and X-Plane use the ac3d model format which dictates the axis system they use.
 

arno

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I don't think the AC3D modelling format dictates anything, I could also export it just as XYZ, with Z pointing up and the file is still valid.

Actually the FlightGear axes seem a little more logical to me, since at least it is a right-handed coordinate system. In FS it is left-handed.

I guess I'll just use some trial and error on this. I have downloaded FlightGear now and I will just try to insert some models I converted with ModelConverterX. That should show quickly enough if the axes are right or not.
 
The disadvantage of non-conventional axis system is its incositence with real-world aerodynamic data.
 
The disadvantage of non-conventional axis system is its inconsistency with real-world aerodynamic data.
 

arno

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Yesterday I exported and placed some objects to FlightGear. They seem ok, so I guess I got the axes right now in ModelConverterX.
 
Arno, just for your information, FlightGear has an active forum, at which you can get any help you might need. At least you'll reach far more FG developers than you'll find here ;)

http://www.flightgear.org/forums

Btw, does this mean you started to check whether it is possible to use NL-2000 scenery in FlightGear? :rolleyes:

Gijs
FlightGear scenery (and too much to name) developer

PS: You can always drop me a message if you need help on anything.
 

scruffyduck

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Arno, just for your information, FlightGear has an active forum, at which you can get any help you might need. At least you'll reach far more FG developers than you'll find here ;)

http://www.flightgear.org/forums

Btw, does this mean you started to check whether it is possible to use NL-2000 scenery in FlightGear? :rolleyes:

Gijs
FlightGear scenery (and too much to name) developer

PS: You can always drop me a message if you need help on anything.
Gijs

Thanks for coming by and joining our forum. I have taken your advice and joined up over on the FG forum. What I said there represents my position on MSFS and FG of course and I do not speak for others :)
 

arno

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Hi Gijs,

I'll check the FlightGear forum as well, thanks for the tip.

Btw, does this mean you started to check whether it is possible to use NL-2000 scenery in FlightGear? :rolleyes:
I am just one of the team members of NL2000 of course, but who knows :). I first want to understand better what the similarities and differences are between the ways scenery is made for the different sims.
 
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