What Quest means by that statement is that Bryce uses the boolean technique for filtering layers. So when you are using a grouped pos-neg combination, what's really happening is the negative is "hiding" from the raytracer, with a cool option to paint the texture onto the positive side. I first ran into this when I was hollowing a sphere for use in one of the contests. To illustrate, make a sphere, duplicate it, shrink the duplicate, set the first to positive and the second to neg and then group them of course. Simple enough! I cut through the spheres (now ungrouped again) with a plethora of randomized negative skinny cylinders, to demonstrate what's happening here... The mat for the first is stock red plastic. The mat for the second, inner sphere is ANY volumetric, with density at 100, no fuzz, no softness. Volumetric materials will not render on the inside of Negative Booleans, apparently. Make any sense? It totally does until you try to set the MAIN, POSITIVE sphere to the same volumetric, which renders what you see on the right. Same scene, nothing different except stated materials. So, aside from personality quirks (me), there are problems with our favorite raytracer (Bryce)... But, in my experience, this would have nothing to do with the interior of a house/building/structure. You may just need to re-examine your hierarchies, I've made very complex structures (Black Tower, i.e.) and shot the camera around inside of them just fine... What I mean is, that you CAN make your interior happen, Bryce WILL let you do that. Just takes some planning, and serious attention to grouping and hierarchies. The above image was merely to illustrate what Quest meant about UnTrue Booleans.