Friday, February 16, 2007

Jonathan McCabe - Very Cellular Automata

A new year, and another exhibition from Jonathan McCabe at Canberra gallery/cafe The Front. The show, Travelling Wave, was shared with painter Luke Nilsen; it included some collaborative canvases, with Nilsen painting over McCabe's digital patterns, and new works from McCabe's Butterfly Origami and Nervous States processes. But also on the (very crowded) walls were images from a new McCabe process, based on cellular automata. In themselves the images are chunks of psychedelic maximalism, similar to McCabe's earlier work. But once again the real hook here is the mind bending and unusually rich generative process.

The generative system involves four linked cellular automata - think of them as layers. "Linked" because at each time step, a cell's state depends both on its neighbours in that layer, and on the states of the corresponding cells in the other three layers. Something like a three-dimensional CA, but not quite; the four layers influence each other through a weighted network of sixteen connections (a bit like a neural net). The pixels in the output image use three of the four CA layers for their red, green and blue values. (The images here show the full image on the left, and a 1:1 detail on the right)

As in a conventional CA, each cell looks to its neighbours to determine its future state. This is a "totalistic" CA, which means each simply sums the values of its neighbours, then changes its state based on a table of transition rules. Now for the really good part: each cell also uses its recent history as an "offset" into that transition table. In other words, the past states of a cell transform the rules that cell is using. The result is a riot of feedback cycles operating between state sequences and rulesets; stable or periodically oscillating regions form, bounded by membrane-like surfaces where these feedback cycles compete. Structures even form inside the membranes - rule/state networks that can only exist between other zones.

The images reinforce the biological analogy, but philosophically (ontologically?) this system is even wilder. It's inspiring to see a formal system where "the rules" are local and variable, rather than global and static. The way things are (or have just been) controls the rules that determine how things will be next - that much is historical relativism I suppose. But here we see regions of self-perpetuating but incompatible realities, competing for space - even states of being that only emerge where two or more reality-attractors meet. An ecology of ontologies, if you will.

McCabe has put up a page with lots of these images, including full resolution (2048x2048) jpegs.

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