Thanks allot nems. I'll add that up to my paper. I also checked allot of games that use massive terrains like aces high 2 and FC3. They use plain skybox and just blend in the far clipped terrain with the horizon color using fog which have the same color as the horizon. I was planning to use morph for lod but i'm not sure how it reacts with stitched terrain. For all this I have to build my own map builder but will be easy thanks to sir sivan's map builder.

One thing that's giving me problem though, some of my units usually air are a physics entity. I'm still A7 user so I use ODE. When a physics entity gets to far enough from the world origin, the objects starts to jitter or shake. Not really noticesable in 3rd person view but in FP view I feel like my aircraft I about to fall apart since each aircraft have it's separate cockpit model and will adopt the aircrafts angle and coordinate. Is there a way to prevent the attached entity from shaking?