A Hybrid Analog & Digital Animation System

Dave Sieg

Image West had been in business several years when I first came there in 1979 as a maintenance engineer. The company had been initially set up by Computer Image of Denver, CO. but had not been able to get a foothold in the Hollywood market. A Canadian company called Omnibus bought Image West, and had been operating successfully for several years. The principals of Omnibus were Cliff Brown and John Pennie. Image West had gained traction by being able to work in real time, due to the analog nature of the Scanimate analog computers. John Pennie felt that the future was in digital or what is now called CGI. So John and Cliff split up. John raised money on the Vancouver stock exchange and formed Omnibus Computer Graphics in Toronto and Cliff became president of Image West. Cliff Brown, (shown at left in an image captured from videotape) asked me to recommend some options for future development directions. In 1981 Digital image-making state of the art was a PDP-11 and a $50,000 framebuffer. There was no commercially available software, so going in that direction would require a bunch of programmers hacking together new tools from scratch. Triple-I, NYIT, and MAGI were about the only people going that route. Image West had always had the advantage of "Real Time", meaning that despite the limitations of the analog rescan technology, it could run right before your eyes, and be adjusted on the fly until the client was happy. But the downside of this approach was a complete lack of repeatability, due to all those knobs and patch wires. It was also difficult to find people who were the right combination of electronic circuit engineers and creative animators. Together with Peter Koczera and Roy Weinstock, then the principal animators, we tossed around various ideas. It seemed we needed digital control of the analog rescan technology that kept us in real time. I had built a D/A interface for an Apple ][ computer and Roy had developed software that we integrated with the Scanimates that gave us a few new tricks we couldn't do with analog alone. This also showed us that digital computers could be used in a variety of ways to track and store the setups needed to repeat a job. But it would be a large, expensive project, and funding it would be difficult for such a small company.

Cliff returned from MIP in Cannes one day and said: "I've got the money to do whatever we need to do... So what do we need to do?" He had worked a deal with the French SFP. Cliff had told them that we had an ongoing R&D project to build a new system. They were coming to visit in 2 weeks to see our lab and work out the agreement. We quickly moved our engineering department into a building next door and bought some new equipment racks to make our operation look good. Using the Apple ][ to control a 3 X 3 matrix, I was able to demonstrate 3D rotation on an X/Y monitor. We called it VersEFX. They signed the deal, and we were off and running!

Since one of the weakest links in rescan technology is the CRT, I built a test jig to evaluate and test CRT performance. The Scanimate's CRT systems had shortcomings due to lack of resolution, and their magnetic deflection limited the bandwidth to a hundred Khz or so. We had a prototype 3D rotation matrix that would work in real-time, but it required the deflection system to run at up to video speeds. So, we had Special Purpose Technology Co. design us a sub-screen CRT (not the one shown here). The reason CRT's tend to have such low resolution is due to the light from the spot bouncing back through the faceplate, which is usually about 1/4" thick to hold the vacuum. If you analyze the spot through a microscope, you can count up to seven rings around it from secondary internal reflections off the faceplate. Some modern film recorders fix this by using neutral-density faceplates, or in some cases coupling the faceplate to another thick faceplate with a laser liquid similar to mineral oil. The SPTC CRT had a specially designed fine grain phosphor deposited on a thin piece of glass (the subscreen) that actually sat a half inch behind the actual faceplate. Thus, the resolution was excellent, because the rings were nonexistent.

Here is the electronics racks that made up the final version VersEFX. The rack at the right held the "master" system, which talked to each "channel" via a IEEE 488 buss. We should have used Ethernet, but in 1981, it was less available. Jim Ryan did an amazing job of writing the assembly code that ran in each system, dealt with realtime updates, playback of animation, and all those lovely I/O registers and their quirks. You can see an ICE (In-Circuit Emulator) probe sucking onto the master processor if you look closely.

Here is a closeup of the CRT section of one bay in the final version. If you look carefully, you can make out the subscreen CRT. Rather than the awkward protruding camera like Scanimate had, I chose to fold up the whole optical path using front-surface mirrors. The whole thing fit into a rack-mounted slide system, and plans were to introduce filtration mid-path at some later point. The CRT was scanned by a COHU camera, which turned out to be a very poor performer. Later plans were to take an old studio camera and split the individual red, green, and blue electronics out to allow registered RGB signals to be animated. Alas, advances in digital framebuffer technology just did a better job of storing an image than the face of a CRT. Also, as it turned out, our high-resolution CRT was TOO high-res! The Scanimate had used that big fat point to fill in a lot of space between scan lines.

This was the VersEFX control console, manned here by Jim Ryan, the project software engineer. The bay came out very much like the original artists rendering above. Unfortunately, despite having shifted all costs over to the SFP, Image West ran into financial difficulties, and the only system built was shipped to France. Peter Koczera claims he went over and that the system was working and they did some interesting things with it, but it was never completed, partly because the design goals were moving targets throughout its development. I learned a lot about managing projects of this size, most specifically how fast technology can change, often before a big design can be completed. It also became apparent how quickly a small company can be swamped trying to do R&D on this kind of level.

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