Yep.

Not good to view the back side of a polygon - takes forever to render.

I'm off to bed, but I did do one good demo render.

Ground plane, two dark one-sided squares, very large, and two spheres.

Light is uniform white IBL, 80% intensity.

Observe the differences in the spheres. The one on the lower right is occluded by two polygons to the left, so its left edge is strongly occluded. The ball on the left is only occluded by one wall on either side, so both left and right edges are bright. The ball on the left, being sandwiched is picking up some occlusion from the more distant parts of the walls.

Observe the bottoms of the spheres. The upper left is 15 inches from the floor and the bottom is somewhat occluded by the ground plane. The one on the right, being only 5 inches from the floor, is experiencing very little occlusion from the ground plane.

The ground plane is experiencing strong occlusion where it is hidden by both walls, on the right side. I didn't include it in this composition, but the to the left of both walls it is also strongly occluded.

Between the walls, there is very little occlusion on the ground, mostly from the distant (higher) parts of the walls and some mutual occlusion between the left ball and the ground. The right side of the ground is also experience proper strong occlusion from the nearer ball.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)