It sounds like your TriMesh tiles are colliding with each other.
You need to create a sub-space containing all of the TriMesh tiles...
Global Space=dHashSpaceCreate(0)
Global SceneSpace=dHashSpaceCreate(Space) ; <<< Sub-Space for TriMesh tiles
Then disable internal space collisions to prevent them colliding with each other...
dSetInternalSpaceCollideMode(0)
Make sure you specify 'SceneSpace' instead of 'Space' in the CreateTriMesh function calls...
trimesh(xx,yy)=CreateTriMesh(SceneSpace,Land_mesh(xx,yy))
The 'CarDemo-TriMesh-X4' demo shows the above method in action.
You need to create a sub-space containing all of the TriMesh tiles...
Global Space=dHashSpaceCreate(0)
Global SceneSpace=dHashSpaceCreate(Space) ; <<< Sub-Space for TriMesh tiles
Then disable internal space collisions to prevent them colliding with each other...
dSetInternalSpaceCollideMode(0)
Make sure you specify 'SceneSpace' instead of 'Space' in the CreateTriMesh function calls...
trimesh(xx,yy)=CreateTriMesh(SceneSpace,Land_mesh(xx,yy))
The 'CarDemo-TriMesh-X4' demo shows the above method in action.