occlusion culling (Nearest big areas disappears)

Hello, Nearest Big areas disappears in occlusion culling when my 1rst Person viewer walk in...

Here is my project :

http://www.scam3D.fr/Scam3d-V26.html

I have experimented many settings (big occlusion areas, differents occlusion areas), and I always have big areas of the scene that disappears when I walk through, and i don't know why... (Maybe because the trees, but i am not sure...)

The Occlusion Culling settings are:

View cell size 10 (If I put a lower setting, it is very long to bake, and it is worse)

Near Clip Plane 0.01

far clip Plane 600

Bake Quality "Production".

I have a unity pro license, and I work on a macintosh 2x2,66 GHz 6-Core with 8GB DDR3

Here are snapshots of the project

All the architecture is done with C4D

http://www.noomuseum.net/img/Scam3d-C4D-PL.JPG

and is imported as an single object set in static

http://www.noomuseum.net/img/Scam3d-YMinh-010.JPG

Other objects are groups under empty objects by localisation in the different rooms of the museum

http://www.noomuseum.net/img/Scam3d-YMinh-011.JPG

Here is the inspector for the occlusion area box

http://www.noomuseum.net/img/Scam3d-YMinh-012.JPG

The Occlusion Culling They are no target because I don't have moving objects others than the First Person Viewer. In this view we can see that Some objects disappear

http://www.noomuseum.net/img/Scam3d-YMinh-001.JPG

The edit view

http://www.noomuseum.net/img/Scam3d-YMinh-002.JPG

The occlusion culling area. I set it like that, without the garden and terrain in the front, because the garden disappear when i put it in the occlusion culling area

http://www.noomuseum.net/img/Scam3d-YMinh-003.JPG

http://www.noomuseum.net/img/Scam3d-YMinh-004.JPG

http://www.noomuseum.net/img/Scam3d-YMinh-005.JPG

http://www.noomuseum.net/img/Scam3d-YMinh-006.JPG

played the browsergame and walked all the way towards the back of the museum without trouble.. I don't really know what's the problem but I did get an error when I played a video which shut my tab down. Nice job on the moddeling by the way.

Ok, The bug come from the trees.

I have made different experiments and it seems that the trees generate some bugs in the occlusion culling Bake.

http://www.noomuseum.net/img/Scam3d-YMinh-014.JPG

I have disactivated the trees http://www.noomuseum.net/img/Scam3d-YMinh-015.JPG

And render a new bake for the occlusion culling http://www.noomuseum.net/img/Scam3d-YMinh-016.JPG

And activated again the trees after the baking http://www.noomuseum.net/img/Scam3d-YMinh-017.JPG

And it works fine now, no more area disappear.

Hope that help...