I don’t really know much about ray tracing but I think Mojoworld uses it. There is an algorithm in “Texture & Modeling A procedural Approach, third edition” but I’m not sure if it’s even close to what you need. I haven’t looked at it in detail because I’m not doing ray tracing. I bought Mojoworld just to try it out but the frame rate is pretty low. It’s engine would not be suitable for games, but it’s still a cool program.

In any case your problem sounds like a Kenton Musgrave sort of thing. I think he either started Pandromeda (they sell Mojoworld) or at least he works there. He’s also a pretty famous author and fractal expert. He sent me email personally when I some issue installing the program. We even had a short email exchange. He sounded like a supper nice guy. You might want to look into his work or contact him.

Has anyone worked on a method for efficiently ray-stepping through the “inside” of 3D+ non-affine fractals ?

I’m asking as I am working on code to ray-trace fractals that will include transparency/diffraction.

So far the only relevant text I’ve found is the brief outline on Wikipedia regarding Distance Estimation for the “inside” but the algorithm requires too many iterations and is not generic enough for the purposes of rendering general 4D number systems.

I’d appreciate any thoughts on the subject :)