Iterated function systems

In the display case between L-systems and classic fractals like the Mandelbrot set, we have IFSs. There is a lot of definitional overlap between these things; mostly the difference is about where they are used and the algorithms used to draw them.

• Why does no-one (seem to) use linearized Gaussian error propagation to choose smoothing kernel size when rendering? would reduce the amount of iterations necessary to overpaint (I think it would; but there must be some reason no-one does it?)
• Is there a meaningful acoustic equivalent?
• At some point I would like to understand how the Barnsley IFS algorithm inferred IFSs from images.
• Construct IFS as a point process / branching process.