Star Wars’ Computer Animation

Sunday, August 28th, 2011

Dan O’Bannon made his name writing the screenplay for Alien, but before that he did some technical work on the computer animation for a little science-fiction film called Star Wars:

George Lucas had hired 24 year-old computer scientist Larry Cuba to create the (at the time) challenging wireframe and vector-based CGI work for the tactical briefing before the attack on the Death Star in Star Wars. Cuba worked out of the Electronic Visualization Lab (EVL) at the University of Illinois, and created the blueprints and graphics using the vector graphics scripting language GRASS (GRAphics Symbiosis System, created by Ohio State’s Tom DeFanti in 1974). EVL themselves take no particular credit for the sequence, but say “[Larry Cuba] stayed at our facility and used our equipment for many months in order to create the sequence.” Cuba created an instructional video about the sequence at the time of Star Wars, and EVL released it in 2008 as a well-viewed 10-minute video on their channel at YouTube.

Cuba used a Vector General CRT, DEC PDP-11 minicomputer to generate the images and recorded the frames by pointing a film camera at the monitor in an automated process which awaited each successive image to be rendered before triggering a frame exposure.

O’Bannon’s first task on Star Wars was to create the final section of the Death Star tactical simulation, wherein torpedoes are seen entering the shaft and descending to the core to cause a reactor explosion. For this O’Bannon made an effort to simulate Cuba’s style, with white lines on black, but added his signature ‘strobing’ at certain points. This end section of Star Wars’ one and only CGI sequence would have been an ambitious addition to the schedule, and Lucas decided that concluding it with animation was the quickest route to completing the scene.

Later Lucas returned to chat with O’Bannon about creating the remaining tactical and computer display animations for Star Wars. Lucas was shuttling between San Francisco and ILM’s facility in Van Nuys at the period, and would sit with O’Bannon sketching out rough diagrams for the tacticals on scrap paper.

Feedback from Lucas was minimal throughout the three-month period in which O’Bannon supervised the shots, though he notes that the director was concerned at one stage that some of the visuals were coming out too ‘colourful’. This is something O’Bannon says he could easily have remedied in advance if there had been more detailed discussion, but in the end the colour in some of the tactical shots was toned down for release.

The one shot where O’Bannon’s team employed computer technology was on the compositing work for the Death Star’s aspect for clearance to destroy the rebel moon Yavin IV. Here O’Bannon praised the great speed at which the Image West facility was able to take the elements that he brought and composite them with motion on an analogue computer. The system was known as Scanimate, and was created by Lee Harrison III, the founder of Chicago’s Computer Image. Scanimate would scan core imagery at twice the horizontal rate of NTSC or PAL and output the various elements composited onto a five-inch CRT screen, which was filmed in real-time with a conventional movie camera. If you’re interested in more detail on how Scanimate worked, check out this post at Siggraph.

Of all the visual effects produced for the original Star Wars, the contribution of O’Bannon’s team has been the least affected by the two ‘enhanced’ re-releases in 1997 and 2005, though we must note that Lucas did decide to change the written language on the Death Star’s tractor-beam generator (above) from English to…well, something else. O’Bannon joked that he was disappointed George Lucas had not taken the opportunity to revamp the screens for the special editions, and that something more interesting could have been done with newer technologies. On this, of course, we can’t fault Lucas; it would not only have removed O’Bannon’s work from the film but substituted a great deal of the original feeling and iconography of Star Wars. Good call!

Watching that how-to video, it seems like they would have been better off filming literal wire-frame models, which is what they more-or-less did for Escape from New York‘s computer displays. The (very different) scene from Heavy Metal, where Taarna rides her pteranodon over the desert landscape, was actually animated using a similar technique, with a physical model of the landscape painted with lines along its edges, so they could fly the movie camera over the terrain and then produce high-contrast photocopies of the film, which could then be painted for the final animation.

Leave a Reply