All animations and stills copyright (c) 1993+ Ryan M. Geiss.
I recently touched up an old C++ ray-marcher I'd written
(like a raytracer, but more versatile),
adding surface-crawling, fractal noise, and
ambient occlusion ray-casting (for lighting).
Here are some of the cool images that I generated with it.
Warning: some of them are very large.
(...and the real versions are often much larger)
Batch 1: added Jan 5, 2010
Batch 2: added Jan 30, 2010
Then, after porting it to the GPU:
Batch 3: added Jan 23, 2011
Batch 4: added June 11, 2011
Batch 5: added March 25, 2012
Here are some much older images,
generated with simpler techniques:
Images added 1996-2000