Review of 3rd USENIX Graphics Workshop

Introduction

The program commitee deserves credit for the broad range of papers chosen. Happily very few papers concerned UNIX itself and the session "Making Noise and Fooling Around" was not about graphics at all: the theme of this session was that we have ears and hands as well as eyes.

All three workshops have been entertaining and stimulating. Where else can you learn about the history of player pianos, how to program fish and how to build your own private telephone exchange?

The Utah Raster Toolkit

This toolbox contains programs for manipulating raster images, stored in a compressed form with a descriptive file header. Image data can be passed between the tools with pipes. Tools included perform cropping, positioning, ratation, compositing, down and up sampling, color mapping, background generation. There are tools to display images on the Chromatics, Iris, HP 300, or Apollo workstations. Images can be converted into Postscript and displayed in systems running X-windows.

Example images illustrated several standard compositing tricks: bullet holes, fake shadows.

A High-End High-Performance Graphics System for Computational Fluid Dynamics

A Cray 2, a 3D colour workstation capable of real-time animation and some software is all you need for fluid dynamic modelling in your living room.

The video shown of this work included beautiful animations of simulated fluid flows around the space shuttle and more abstract objects. The system can display animations of particle velocity, pressure and temperature. A fascinating display problem arises, because the basic data is a 3D volume changing in time. The authors illustrated one solution: transparancy, with an image of contoured transparent surfaces.

Recollections

Ed gave a tour of his work, which combines performance art, computer graphics and audience interaction. His work "Recollections" can be experienced at the San Fransisco Exploratorium. A camera extracts a silhoutte of whoever it is filming. This silhouette is then processed in real-time. The resulting colour image is projected on a large screen in front of the participants. The most striking effect is a colourised visual echo. As you move an arm, for example, the movement is followed by a fading trail of earlier arm positions. Each elementof the trail is coloured differently as of your arm is animated by rainbow.

Pictorial Conversations:Design Considerations for Interactive Graphical Media

Rob had by far the best transparencies at the workshop. The proceedings are worth $10 just for these storyboards. They describe the design process as a conversation between designers and consumers through the medium of a pictorial conversation system. Diserable properties of such a system were presented by describing face-to-face human conversation and traditional media.

The presentation was thought provoking. The ideas apply to many design situations: not just those using pictoral representation: sound design, for example.

Plasm: A Fish Sample

If your fireplace at home has a TV set in it showing a video-tape of a fire burning, you will really want the goldfish bowl of the future, demonstrated in this paper. A Silicon Graphics IRIS workstation was programmed to simulate a small underwater ecosystem. Real goldfish have rather predictable behaviour: they swim around and wait to be fed and occasionally float lifelessly to the surface. With Plasm you can ascribe behaviours to the fish and interact with them. There is more to all this than pretty animation: most of it tied to the questions: how do you describe behaviour and when is it interesting to build systems by describing their behaviour?

A Semantic Net Browser

This talk caused much heated discussion on the how to display knowledge graphically. The authors idea is to avoid the difficulties of previous approaches by not mapping information to the display using metric space or attribute matching. Instead he uses the display to describe only relations between information and gives the control of which relations and their relative importance to the user. The user explores the semantic net like a spider moving around its web.

A Multi-Representation, Bitmap Interface to the UNIX File System Constructed from Cooperating Processes

The prototype user interface to the UNIX file system presented here is called FM, for file manager. The interface, like the Macintosh Finder, provides a visual representation of the file system graph, and a textual representation of file attributes. It also includes a text editor. What is interesting and promising about the authors' approach is that these functions are built as separate tools and bound together using an IPC mechanism rather than lumped together in a large intractible application.

Millions, Billions, and Trillions of Spheres

Chemists find models of molecules very useful in their work. Physical models of large molecules are expensive and slow to construct and are often very fragile. Computer graphics offers a flexible solution to their problem: fast rendering of spheres. The author gave a history of this problem citing the work of Ken Knowlten. Lorinda Cherry, Tom Porter and Nelson Max. By taking advantage of the symmetry of the sphere and their limited numbers in most molecules, the author precompute sa few spheres and creates an image by compositing replicas of these spheres. The results shown were visually striking. Even more impressive is that they were computed at the rate of 22000 atoms/minute.

Scattered Thoughts on B-Splines

These were not scattered thoughts at all. This was a good tutorial on B-Splines and their application and misapplication. It was interesting to see how B-splines can be adapted to achieve effects of more complicated spline formulations and at a lower computational costs. Spencer illustrated this with tensioned splines.

Procedural Spline Interpolation in UNICUBIX

Computer Science Division
Electrical Engineering and Computer Sciences
University of California, Berkeley

Carlo handed out an interesting visual questionnaire. We were asked to draw pleasing curves around sets of points. This was to aid him in the quest for heuristics for pleasing curve fitting, which is an essential part of the UNICUBIX system. UNICUBIX is an extension of the UNIGRAFIX modeling and rendering system, which was presented at the previous conference. UNIGRAFIX only supported polyhedral objects. UNICUBIX supports objects with curved edges and triangular and quadrilateral patches between curved borders. A set of rules were described which enable the system to fit pleasing curves and surfaces through a given set of vertices.

Communications System for Transmission of Voice/Data on the Ethernet

This talk described an experimental telephone system which used ethernet for transmission instead of conventional telephone wiring. It is not easy to use ethernet for this purpose as intelligable speech requires that packets arrive in order and with a fixed latency. The prototype telephones described each had two RS232 ports.

User Programmable Telephones

Porting UNIX to the Bosendorfer

This has not implemented this yet, but the fascinating history of player pianos was presented together with some video tapes of the piano, the Media Lab and their demonstration-oriented research.