For those who want to create similar looking (in quality) graphics: Check out asymptote [1] (IMO one of the most undervalued software in the TeX community). It has a pretty nice programming language only made for drawing. It's got types, structs, modules etc and is a real joy to program. It's also very quick to compile which allows for very quick feedback loop (almost "live" editing with a keybinding on vim/emacs)

Of course, if you're already a TikZ pro then just stick with that.

To give you a taste:

http://www.marris.org/asymptote/animations/index.html

http://www.piprime.fr/developpeur/asymptote/surveys-asy/frac... (many more examples)

[1] http://asymptote.sourceforge.net/