basic doubts in unity

Scene & World Building Terrain
1

a few doubts i had regarding unity

  1. where do i find occluders, portals and zoning.
  2. how can i get my terrain tree in side and use them as terrain brush( i placed my obj file and textures in the Assets\Standard Assets\Trees Ambient-Occlusion but still do not get them as brush)
  3. is there any double sided material and normal flip option in unity.
2

  1. There are no such mechanisms outside of Unity iPhone unless you implement them

  2. You can not. Terrains must be created from heightmap (see the terrain menu on top)

  3. that can be achieved through modifying the shaders to render two passes, one in normal and one with inverted normals. There are examples on this on the board.

3

thank you