The images in "Liquid Selves" and "Primordial Dance" by Karl Sims are rendered to perfection. "Primordial Dance" reminds us in its structure of the colors of a kaleidoscope. "Liquid selves" transforms faces and reveals them (and their contents) as masks. The soundtrack is provided by Peter Gabriel.

"Primordial Dance" is an experimental animation containing a progression of abstract textures and patterns. It is a study of emerging and transforming mathematical equations that might be considered "visual music" in that it attempts to provoke emotion with underlying structure and complexity without relying on specific representational entities.

Techniques analogous to natural biological processes were used to create the images in this piece, and the results are unusual organic effects that perhaps reflect the nature of the methods employed.

"Artificial evolution" techniques allowed complex equations to be discovered that automatically generate a wide variety of different textures, colors, and shapes. An artist and a computer collaborate in this interactive process to produce results that neither could easily produce alone. The computer takes care of the equations and the procedural information, and the artist provides the aesthetic information that directs the outcome of the process: first, the computer generates a collection of simple equations or "genotypes" that each describe a mathematical process that synthesizes an image or a "phenotype." (This is analogous to DNA describing the development or synthesis of an organism.) The user then observes these resulting images and selects those that are aesthetically preferable. Next, the computer reproduces the equations of those selected images and performs random mutations and crossovers between them to create a new generation of images to select from. Some mutations cause only slight variations in the equations, while others cause significant modifications and sometimes increase their complexity. The user again selects those images that are perceptually desirable, and the cycle repeats for a number of generations. The equations and their corresponding images can become more and more interesting as the evolution proceeds, and very unusual and complex results can eventually occur.

This cycle of repeated variation and selection has similarities to natural biological evolution, although here the "organisms" are simply pictures and the survival abilities or "fitnesses" are provided interactively by a godlike observer. An alternative interpretation of this process might be that the computer attempts to "learn" from the user about how to produce aesthetically pleasing images. The user provides positive feedback for those images that are most liked, and the computer reacts by generating more images in that direction.

An important advantage of using this technique is that it does not require the user to understand the complex equations involved. This can give artists access to these kinds of algorithmic tools, without the burden of having to learn the mathematical details. In fact, it is possible for complex equations to evolve that surpass what any human would easily be able to design or even understand.

Motions were created by performing "genetic cross dissolves" between pairs of similar equations. The computer analyses the equations and automatically calculates in-betweens to generate a smooth interpolation from one image to another. The animation in "Primordial Dance" was created in this way by using interpolations and even "genetic splines" across sequences of many different evolved images.

A variation on the artificial evolution methods above allows equations to also occur that perform image-processing on a given source frame. An image of a human face was manipulated and warped by evolved procedures to create the final sequence in the piece. This system was implemented in Starlisp, a parallel version of Lisp, and is executed on a Connection Machine CM-2, a data-parallel supercomputer. Color images can be quickly calculated from the genetic descriptions by assigning one virtual processor for every pixel and calculating colors for all pixels of the image simultaneously. These techniques could be implemented on any computer, but the speed of computation affects the level of complexity that can be achieved while still maintaining an efficient interactivity with the user. As computers become more powerful and more available, these kinds of techniques will hopefully be able to produce more and more interesting, useful, and diverse results.

"Liquid Selves" depicts the upcoming struggle between the virtual and physical sides of ourselves. As technology brings us the age of virtual worlds, our existence as individuals becomes less and less dependent on our physical being. Our virtual identities become more powerful and flexible, but also unstable and difficult to define. Our consistent recognizable faces are left behind and all faces become masks. The ability to drink from and contribute to the global information pool is greatly enhanced, and this will affect the course of civilization, but the effective destruction of our bodies is a possible consequence.

Technical Background

A collection of different techniques was used to produce this animation. Particle systems, artificial evolution, morphing, and various image processing and compositing methods were all employed.

Particle systems were used to assemble, manipulate, and disassemble images in unusual ways. One particle was created at every pixel of a two dimensional image, such that the image made of particles could then be manipulated in three dimensions. Images were twisted, swirled, and shredded into pieces with a particle behavior language that provided procedural operations for controlling many thousands of particles. Various forces pulled the particles away from or back towards their original locations on the image, and vortex operations moved the particles in fluid-like swirling motions.

Two different applications of "artificial evolution" techniques contributed to the creation of this piece: equations that produce three dimensional shapes, and equations that process and warp two dimensional images were both interactively created.
Three dimensional surfaces were procedurally generated by parametric equations which were mutated, mated, and interactively selected by the user to find interesting shapes. Interpolations between these evolved surfaces produced unusual three dimensional transformations from one shape to another. Images of faces were finally mapped onto these transforming surfaces.

Images processing and warping functions were also created using artificial evolution techniques. Pictures of human forms were processed by the user to search for desirable effects. Morphing techniques were used to produce transformations between two dimensional images of various faces and masks. The original images were simultaneously distorted and dissolved to create smooth interpolations between them.
Other procedural image manipulations, compositing techniques, and texture generation were also used. Procedural noise textures were generated for some of the backgrounds, and vortex warping operations were used to swirl the clouds and face patterns in the sky. Finally, models of shining human faces were included using traditional three dimensional polygonal rendering methods.

HW: Connection Machine System
SW: Original Particle System, Artificial Evolution, Image Processing SW