You can try make the track, and separate in parts and make a group of every part (if you use Sketchup) and then export to 3drad the separated parts of the tracks. And in game you can use level of detail, when the player is close to a part of the track and hide the part of the track when is not in camera anymore.

Ah you didn't said that on the topic, but the idea was for the skinmesh so...

Ah you didn't said that on the topic, but the idea was for the skinmesh so...

yes your idea is for skinmesh.
Thanks Facujk101 for your help.

can anyone help me?

first of all... it would be best to use a rigidbody as a non visual element for physics interaction in this circumstance... which would prompt one to wonder, why would you need to implement LOD for a non visual element...

Hi Mike
I can't Understand your mean "non visual element" can you explain more clearly?

non visual  means you don't see it...

--Mike

I know 

I need explain more clearly about Rigidbody that why is non visual element and can't implement LOD for it? I know Rigidbody use for Physics and can't see it, but my model have big size and much polygon (About 25000-30000 polygon) and might decrease FPS. you say don't Need use LOD for it. can you give a little explanation? and if I make my mode as Rigidbody in 3drad is correct?

Thanks.

you know??!!  then why'd you ask in the first place...

I know the Mean "non visual" is  "means you don't see it"

hey, i'm gonna assume that this is a language thing, and continue... 

Right, I don't good Explain what is my mean.

Level of detail
From Wikipedia, the free encyclopedia
In computer graphics, accounting for level of detail involves decreasing the complexity of a 3D object representation as it moves away from the viewer or according other metrics such as object importance, viewpoint-relative speed or position. Level of detail techniques increases the efficiency of rendering by decreasing the workload on graphics pipeline stages, usually vertex transformations. The reduced visual quality of the model is often unnoticed because of the small effect on object appearance when distant or moving fast.

Right, LOD make decrease quality of a 3D model according distance.

second, ask yourself the following...

if LOD is implemented for a large scale rigidbody track... when will the second stage of the LOD implementation be activated... if it's a single big track, when will it ever be far enough from the viewer to have the second stage of LOD pop in...

I don't understand.

I no knowledge about some things so I ask the questions and thank you for your answers. sometimes your answer is very hard to understand and Makes me confused because I don't have Previous knowledge about it.

I need know some things before made tracks. but still I can't understand your answer. if Possible take the time to answer my questions, thank you Mike.

I understood :
LOD make decrease quality of a 3D model according distance. and can't implementation for Rigidbody because Rigidbody is non visual.

Now need understand for use track in 3drad I should make it as Rigidbody. right? I think can't make as skin Mesh because the Cars can't be placed on it.
if your answer is yes, I want know split one track to some objects is the right way? however I can't implementation LOD for it.

And what do you suggest for non decrease FPS after import big track into 3drad?

Thanks

1- I want create track in jungle like Jungle racer game. with maximum 25000 - 30000 polygon.

2 - my track have straight and curves.