Amazing what you can find on wikipedia... Now I am fascinated with the idea of a concave hollow Earth.
I was wondering... is there any means in TG to turn the whole planet inside-out, just like this outlandish theory posits? Or create this type of terrain somehow? In other words, to build a scene on the inside rather than the outside?
No, putting camera underneath the surface is not the "simple" solution - if the camera is "fossilized" you get pitch-black shadows.
So anyway, is there any chance to render this in TG? ;) See the graceful picture attached to this message to get the visual idea of what I'm talking about.
https://en.wikipedia.org/wiki/Hollow_Earth#/media/File:Concave_hollow_Earths.svg
I attempted caves by using a sphere with negative radius. Works. Lighting is the problem, because the sphere creates its own shadow, so you need other means.
Um, yeah... Obviously you need to put sun in there somehow. :-\
Maybe this is a wacky idea but... If you move the entire world to where the sun origin is located in the program...?
Just use a new lightsource (which the sun also is of course), inside the sphere/planet. But it's a bit awkward all.