English: The xy-plane here represents the Re[c] and Im[c] plane, just as canonical Mandelbrot sets are considered. The z axis encodes the values that z[n] takes during its iteration. Thus, the areas unbounded (not in the Mandelbrot set) are mostly dark, and the areas bounded during iteration add up.

This file was rendered using open-source code freely available here: https://github.com/jonnyhyman/Chaos

For a YouTube video by Veritasium, as seen here:

https://www.youtube.com/watch?v=ovJcsL7vyrk