I am not sure this thread is talking about collision but from my little experience the ellipsoid collision is tricky to tune for desire result.
For moving object over a un-even surface, the sphere collision hull that mean a sphere collider is prefer over ellipsoid. i.e. in my old project in order to make the tank move smoothly I use c_setminmax to make a sphere collision hull.
From 3DGS manual:
http://www.conitec.net/beta/collision.htmGliding can be restricted to the XY plane by setting disable_z_glide to 1. By default the ellipsoid can move up any slope, no matter how steep it is. To restrict this motion you can alter the global variable move_min_z. If the contact normal's Z axis is less than this minimum value no gliding along Z will take place at all. Hitting the ground plane will result in a normal.z value of 1.0 (pointing straight up). Hitting the ceiling will yield -1.0 (straight down) and a head on collision with a perpendicular wall will have a normal.z value of 0. The default value of move_min_z is -1 which allows gliding at all angles. If you were to set it to 0.5 instead all slopes steeper than 60 degrees (=acos[0.5]) would cause the entity to stop and not glide up. This example is valid only for a spherical hull. For an ellipsoid some trial and error is required to find the right value. Rather than relying on move_min_zit is recommended that you place invisible entities in front of steep walls to block them off.
Since not much object is totally spherical and no level is just a flat surface, that's I think is the problem of collision system in 3DGS.
Though I haven't got much experience in Unity, I feel that their Capsule Collider is much more sophisticate compare to 3DGS's ellipsoid collision. I don't know the math behind collision, but I think the hemisphere of the Capsule is the key to make the collision works.
http://unity3d.com/support/documentation/Components/class-CapsuleCollider.htmlOf course that is just my understand and it could be wrong.
