The project of Himmelstadt asks if self-organizing system could be systematically regulated according to the user’s preference for global behavior. Self-organizing has benn appreciated by architects and urban planners for its richness in the emerged global behaviors, however, design and self-organizing is contradict in principle:

the former approach often assumes a methodical step-by-step planning process with predictable outcomes, whereas the later involves nondeterministic spontaneous dynamics with emergent features. - Prokopenko 2008

This experiment is to evolve the rules of Cellular Automata (CA) according to the observer’s preference for global patterns. A CA with eight neighbors is employed, the state of a cell in the next iteration is determined by the current states of the 3×3 grid around it. Thus, the updating rules is a function that has nine boolean inputs and one boolean output. The task is to derive a specific function which leads to a preferred global behavior. Based on the interface, the user could select one particular CA to see an animation of the evolving process. By these images or animations, the user could input his preferences (give high scores to several favourite ones ). Then the computer would create a new generation of CAs by reproducing, mutating and crossing the preferred ones. The procedure is very similar to genetic algorithm, in which the new generation always has new variations and probabilistically moves towards certain direction imposed by the selection.

At the final stage, the selected CA is used to simulate the development of a city district. There are two aspects which are valuable for architects or planners. One is about the form which might contain interesting shapes or special topological structures; the other is about the stability of the dynamical system: some CAs would convergence to a certain pattern (towards equilibrium) even with different initial states; by contrast some others would have very different results even with similar initial states.

Programmed in Processing

CAAD/ETH MAS module with Brian

January 2010

video:

Evolution of Cellular Automata based on user preference