Hollow Prim inner wall mismatch?

I was building a game when I stumbled upon something weird (or not...)

If I make an object hollow, and use the inner space to confine other prims, I find that the 'inner walls' of the hollow object seems to stretch for another five say ten cm?

That is, a ball bouncing on the inner side of a hollow object will bounce BEFORE it reaches the inner wall...

I've had another see the phenomenon, and I've seen it on at least three different shapes, so I don't think it's anything local.

Is this a known bug? What can be done about it?

And, I've also noted that I can shoot object 'thru' walls if the velocity is high enough. But I think I can see why, so I shouldn't be surprised, right?

Havok1 has a precision of about 0.1m. This causes a gap between objects and makes objects 'float' or bounce like you described. Havok2 will reduce this gap significantly.

Also Havok1 is 'time frame based' and only checks collision with objects on the 'border area' of them. So this explains the fact it's penetrating shields/walls. As it's on one side of 0.1 gap from your wall in timeframe 1 and already on the other side of the wall on time frame 2.

Don't try to increase the size of the wall, it won't make the collision detection better (like I said, it only checks the 'border area' of the prim.) You could add more walls, but the object could be caught between the walls in that case... causing even more fun
(and lag)

A thousand thanx for an excellent answer!

Two follow-ups, tho;

1. Is the precision 'gridded' or is it a 'tolerance', that is, does the borders absolute position have anything to do with it? Will moving the object change anything?

2. How long is a time-frame? If I knew that, I could calculate a 'maximum safe velocity' given my objects scale, right?

I don't think the absolute position has anything to do with it.

The physics simulation usually runs at a maximum of 45 frames per second, so each frame is 1/45 seconds. This means that a bullet moving at 45 meters per second will move 1 meter per frame. There is a maximum speed of about 256 meters per second.

Havok 1 sometimes does STRANGE things. Last night, I was working on a build, and had a simple 6x10x.15 surface used for a floor that simply wouldn't hold me up. If I was flying, I could fall right through it (but not fly back up from below). If I turned off flying, my AV went nuts, looking like it was trying to swim. One time, my AV settled down into the object at chest level, the way it might look if that were the surface of water in which I was floating. Nothing I could do do the object as far as resizing, linking, etc. would fix the problem.

I made an exact duplicate of the object, and it did not exhibit the same behavior. I think this is the basis of 'prim torture', isn't it? Where a change you make to a prim is not reversible by simply undoing the change. Sometimes this can be done with the editor, sometimes with LSL scripts, which can do a few things the editor can't. I wonder how this behavior will be affected by the update to Havok 2. Will it be possible that certain objects will become impossible to reproduce in Havok 2 if they were made before the upgrade?