Terrain2Objetc use parameters and modify parameters by default ?

Hi

I look for an explanation detailed(retailed) on Terrain2Object.
I found only this link http: // wiki.unity3d.com / index.php? Title=Object2Terrain.

I make road projects. My working zone is made by edges of ground of 512x512m of quoted(esteemed).
On my current project, I have a zone of 15 km approximately (30 edges) by 10 km (approximately 20 edges)

I try to have an optimization of the resources of the pc.

I know to what are of use Tree distance, Bilboard start, Max Mesh Trees, but not for the other details
I put these parameters



I also try to modify by default the parameters.
Example paves 512 x 512 instead of 2000x2000 by default.....