[ODE] splitting the world in multiple trimeshes

[Pancini, Ettore]

hi,
right now my world is composed of a big trimesh.
i would like to split the scene in some 'chunks'
subdiving the scene in some smaller trimeshes

so i created a prototype scene, just to proof the concept:

the scene is a checkboard with a sphere rolling over it.
the checkboard is composed of two trimeshes: one trimesh for 
black squares and the other trimesh for the white squares 
(mmm.. let's hope you can mentally visualize it!)

and i incourred in two problems:
1) the minor problem is collision. the two geoms seems to generate a lot of collisions, slowing down a lot the simulation. this seems logical, and i think i'll solve this with collide bitfields 
2) the biggest problem is 'seams'. when the sphere rolls from a black tile to a white tile (effectively passing from trimesh A to  trimesh B), the sphere jumps, like if there was some bumps.

i know my english is bad, i just hope you can understand anyway and give me some advice,
thanks in advance, 
Ettore