Collision on small objects doesn't work?

I’m experimenting with several things in BGE for a couple of game ideas. I have several “marbles” (actually just a simple plane with a glowing orb texture UV mapped to it and set to Halo) set up as Rigid Body actors under the Logic panel. These marbles do need to be a little bit on the small side.

I notice that if I set the collision radius smaller than 1, usually below 0.7, or if I set the size of the marble objects small enough, a few or all of the marbles will pass through the floor. This happens whether or not the object is an actual solid object versus a flat plane. If I make the marbles or the collision field big enough, it will sort of work, but then I still have the issue where, 1. they look too big for the scene, 2. they seem to “hover” above the floor, 3. if I still set the collision field too small to compensate for larger marbles they’ll pass through the floor, and 4. if I make the marbles small but have the collision field big enough to compensate they can’t get in close proximity the way I want.

Is there a correction for this or is this just a bug that I have to bear and keep my objects/collision large enough? And if that’s the case, why even allow for collision fields too small to be detected? It makes no sense if it’s not usable with the physics engine if I have to have a bunch of small objects going everywhere. Ideally I want small objects to be able to interact with each other in close proximity, but the BGE seems very flawed in a lot of respects when it comes to physics.

It really is just the physics engine failing. They’re not really good at calculating collisions between really small objects.

You could scale up your entire scene until the working marbles are small enough in comparison to the rest of the scene…

I figured as much. I was hoping to avoid that, but if I must, then I suppose I must. I dare say they need to really work on the physics engine a lot more. It could be better in all respects. Collision is pretty bad and gravity and mass just don’t work the way I’d expect them to. Furthermore there’s this seriously annoying issue of solid objects “floating” above a floor. A derivative of this issue is if you have several objects in very close proximity that suddenly “jump” and move away from each other when you go into game mode. In fact, objects won’t even actually touch most of the time, just bounce off an invisible barrier. I would expect something as simple as collision on that level to have been implemented better than it is.

Blender 2.48 has a new Bullet version that’s supposed to allow for much closer collision bounds, you can set the margin yourself in the advanced settings, setting it high could help with small object collision.