Interactive Evolution of L-System Grammars

Evolution of Lindenmayer Systems (L-Systems) provides a powerful method for creating complex computer graphics and animations. This paper describes an interactive modelling system for computer graphics in which the user is able to “evolve” grammatical rules and surface equations. Starting from any initial L-System grammar the evolution proceeds via repeated random mutation and user selection. Sub-classes of the mutation process depend on the context of the current symbol or rule being mutated and include mutation of: parametric equations and expressions, growth functions, rules and productions. As the grammar allows importation of parametric surfaces, these surfaces can be mutated and selected as well. The mutated rules are then interpreted to create a three-dimensional, time-dependent model composed of parametric and polygonal geometry. L-System evolution allows with minimal knowledge of L-Systems to create complex, “lifelike” images and animations that would be difficult and far more time-consuming to achieve by writing rules and equations explicitly.