John Kahr's "Supercluster" image was rendered using radiosity which makes it appear photorealistic.

The "Supercluster" image was created with cgiStudio, a proprietary software package in development at Blue Sky Productions in Ossining, New York. The software uses its own programming language which is reminiscent of the C language, but it relies more heavily on solid geometry and Boolean modelling than polygonal meshes to create images. Because it is based on solids, the software is particularly well suited for ray-tracing, a very robust technique for creating CG (computer generated) imagery, which is the foundation of Studio's production.

"Supercluster (5000 spheres)" was modelled using Studio's language. Studio's ability to model complex imagery using simple programmes appealed to me, and as I had no previous experience in programming, creating the cluster images was a way of learning. The Studio programme creates several thousand spheres that are clustered around randomly distributed points.

The image was rendered using "radiosity". Radiosity is an advanced lighting model that reproduces the inter-reflection of light between diffuse surfaces. A good example of this would be a sunbeam shining on a red floor in a room, causing the whole room to take on a red hue. In my view, the ability to recreate this subtlety of light interaction is the most exciting thing to happen to CG imagery since people started using computers to make pictures, and it pushes the realism and beauty of computer pictures into a new realm. As soon as one starts to work with radiosity, the traditional methods of lighting with computers become obsolete. For instance, it is no longer necessary to use ambient light to make images look balanced: the ambient is calculated correctly and automatically.

Radiosity provides many of the missing visual links that prevented CG imagery from appearing truly photo-realistic. With radiosity, it is even possible to avoid using traditional lights altogether, substituting them with boxes, spheres, etc. that have a brightness, or "inner" colour. These bright objects cast light onto other objects, and the quality of light can often be very soft and beautiful in contrast to the hard edged point source lights often seen in CG images. This use of bright objects to light scenes is the way "Supercluster" is lit. The clusters are floating in a box with an open top, and the brightness of the background "shines" light down into the interior of the box, illuminating the spheres. There are no lights used in the image.

Reviewing the last few paragraphs, it must seem like an incredibly convoluted path for an artist to have to travel before he / she can produce an image. In terms of the entire process, the artist's job is limited to providing instructions to the software. My role is one of high-level direction, building and saving programmes, making models and changing parameters. It's a way of working that involves endless editing and manipulation. Currently, I'm using the ideas and models from "Supercluster" in the next series of images. The part of the process that is tedious and repetitive is, as usual, done by the software itself and the computers. I feel comfortable now with it as a legitimate tool, like a pencil or paintbrush, because for the first time, the richness of the imagery rivals that of other media.

The question why I use computers to make images, has a few different answers. I work as a CG animator every day at Blue Sky, so I'm constantly using computers. I'm always aware of the capabilities, the possibilities of the emerging technology, and I want to push the technology to see how far I can take it.

The most personal reason I have for using a computer is more difficult to describe. I think it has something to do with creating little worlds and exploring them. There is something very magical, almost mystical about creating a scene that exists as ephemeral instructions and scripts, fleeting 1's and O's, and seeing that world drawn, pixel by pixel, before your eyes. To see it given solidity with shadows and light. Each time I view the "Supercluster" scene from a different location or change the cluster configuration, I always get the feeling of discovery and exploration when I see the image finished and survey the complex topologies. When production begins, the artist stands back and watches, the creative process rests, as the software draws the scene, filling in the shadows in ways one never could have predicted, mimicking the behaviour of reality. The artist views the image and responds. This dialogue between artist and machine is one I find particularly encouraging, pushing me to make images, like no other medium I can think of.

Technical Background
HW: Hewlett-Packard HP-735
SW: cgiStudio (Blue Sky Productions' Proprietary)