In "Panspermia" by Karl Sims, a seed falls onto a barren planet and sprouts all kinds of different plants.

"Panspermia" is the name for the theory that life exists and is distributed throughout the universe in the form of germs or spores. This piece depicts a single life cycle of an inter-galactic life form, as an unusual example of a self propagating system A seed crashes onto a barren planet and explodes into aggressive forms of botanical life, which grow into tangled forests and cover the planet's surface. Eventually cannon shaped plants emerge and fire new seeds back out into space to complete the cycle.

In this work, I attempt to bring together several concepts; chaos, complexity, evolution, self propagating entities, and the nature of life itself This unusual botanical form of life, reproducing itself from planet to planet throughout space, is in many ways analogous to other self replicating systems, including humans, entire species, and even ideas. A window into this panspermic system will hopefully expand awareness of self propagating systems in general, as well as inspire thoughts about our entire planet of life as a single entity.

Technical Background

Original software was used to procedurally generate the structures and movements in this work. Plant growing simulations, particle systems techniques, and physical simulations were combined, to create a variety of effects. These simulations as well as the 3D rendering calculations were performed in parallel using Connection Machine CM-2 computers.

The plant structures in "Panspermia" were procedurally created with a continuous growth model. A set of 20 "genetic" parameters describing fractal limits, branching factors, scaling, stochastic contributions, phototropism, etc., were used to generate 3D tree structures consisting of connected segments. Locally acting growth rules use these 20 parameters, and the hierarchy location of each segment in the tree, to determine how fast each segment should grow, when it should generate new buds, and in which directions. Using this approach, plants could be grown in arbitrarily small increments for easy simulation and animation of the developmental process.

"Artificial evolution" techniques were used to find sets of values for these genetic parameters that specified plants of a wide variety of shapes and sizes. The computer generates random mutations of sets of parameters, and the user interactlvely selects those resulting tree structures that survive and reproduce to create each new generation. This process of "survival of the prettiest" repeats until interesting shapes emerge. Plants can also be mated with one another to mix traits from separate individuals.

This artificial evolutlon process has similarities to Dawkins' "Blind Watchmaker" program in which two-dimensional "biomorphs" are interactively evolved to demonstrate the Darwinian process. Here, this method has been extended to create three-dimensional structures that can be further manipulated and animated. These techniques of random variation and interactive selection can provide computergraphics users with a tool for exploring complex procedural models without requiring knowledge of the cumbersome underlying process involved. The20-dimensional space of possible plants can be effectively navigated without requiring an understanding of the specific effects and interactions of the parameters.

After plant structures are evolved in this way, the corresponding genetic parameters can be saved for further manipulation. Solid polygonal branches can be generated with connected cylinders and cone shapes, and leaves can be generated by connecting sets of peripheral nodes with polygonal surfaces.

Shading parameters, colour, and hump textures can be implemented to make bark and leaf surfaces. Dynamically and cinematically controlled movements can also be applied to the tree structures. Mass and spring systems can be created from the segments of the structure for dynamic simulations, and procedural swaying motions can be achieved cinematically by giving relative rotation and stretching oscillation parameters to each segment, dependent on its placing in the hierarchy.

Particle systems techniques were also used to procedurally create some of the effects in "Panspermia". The slowly vortexing galaxy, impact debris from the crashing seed, the explosion, and smoke vortices from the seed shooters, were all animated by providing global behaviour rules that determine the motions of thousands of particles.

For me, it is important to consider the computer as not just a fine arts medium, but as an artistic tool whose limits can be expanded. Ideally, a computer would allow the realisation of virtual worlds and images, without limiting the levels of complexity of the resulting style. In "Panspermia", I hope to have demonstrated a step towards these difficult goals.