High Performance - Low Cost
Gregory F Gustin
Revolutionary technologies are now appearing to support realtime simulation. Our industry has come a long way since the advent of Ed Link's original "Blue Box" flight simulator. Rather than submitting the pilot trainee to the confines of a tiny cockpit relegated to simulated flight through only night or instrument conditions, pilots can now avail themselves of training devices that are so life like in performance that governing agencies frequently qualify pilots to fly multi-million dollar aircraft having trained only in the simulator. High speed, complex parallel computer systems, performing hundreds of millions of calculations per second, processing very accurate data packets, help provide the pilot trainee with the device that is so accurate in its representation of the simulated vehicle that oftentimes he forgets that he sits in a trainer versus the actual device.
However, it is the visual subsystem which is responsible for recent acceptance by the user community that simulation devices do in fact offer the necessary performance capabilities required for advanced training. The exotic flight simulators used today by the military and by commercial air carriers incorporate multi-million dollar computer image generator (CIG) visual systems. The visual simulation industry has progressed in less than ten years from the delivery of night only systems, to dusk/night, and finally to full color daylight displays.
The first CIG device suitable for training began its evolution at General Electric in the early 1960's. GE undertook this effort on behalf of NASA to support vehicle docking training for the Gemini Program. The earliest versions of the device displayed little more than a checkered earth surface and simple vehicle replication. Development of the basic technology continued during the next ten years, and by 1972 GE was able to deliver to the Navy the first full color raster CIG device for use as a visual flight simulator in military training applications. Called the Advanced Development Model (ADM) or the 2F90, it was employed to measure the effectiveness of computer generated imagery for pilot training.
Although this prototype system was found to provide inadequate velocity and attitude cues for lineups and landings on a simulated aircraft carrier, the potential of CIG technology was not itself held in question. Rather, as GE continued to evolve its system's capabilities, other major companies undertook development of similar devices.
McDonnell Douglas introduced the first CIG system to the commercial airline industry in 1971 with the installation of a Vital II system on a Pacific Southwest Airlines (PSA) 737 flight simulator. This prototype system demonstrated what could be achieved by calligraphic techniques (lines and light points), and it impressed the FAA sufficiently to gain approval for use in commercial pilot training as a substitute for flight hours, and even as a substitute for airborne currency (line) checks.
During the early 1980's, CIG capabilities increased profoundly, but the prices remained very high. Color day displays, introduced in the late 1970's for several million dollars, continued to cost nearly an additional million dollars per channel over dusk/night systems. Anti-aliasing, a popular enhancement demanded by many customers to smooth the "stair-stepping" found in raster systems, as well as moving models independent of dynamic background scenes, could now be provided with the most sophisticated systems, but only for a few very well funded customers.
Finally, cost did become an issue. The user community recognized that it could no longer afford the top of the line systems if the pricing continued to remain at its current level. Without low cost systems, the need for trained operators would remain insatiable. Without low cost systems, we would suffer not only from too few trained operators, but those trained would not be of the caliber that we are accustomed to today.
Many training systems were soon fielded using "visual devices" that were available as a result of the tremendous performance increases found available in the computer graphics/workstation community. Unfortunately, low cost soon meant low performance. The minimum standards used for the past twenty years of visual simulation seemed to wane with the excitement of finally being able to acquire visual devices for less than one million dollars. For example, realtime update rates, to some, seemed to be anything that updates at more than once per second, rather than 60 times per second. High resolution and anti-aliasing were also forfeited. The conventional wisdom of high fidelity users had been that low cost systems could not be delivered with the same performance characteristics available from the higher cost systems.
Despite conventional wisdom, low cost visual systems have come of age. In the past four years, Paragon Graphics, Inc. has provided irrefutable proof that a fully-featured CIG visual simulation system could be manufactured, integrated and operated for less than one-tenth the previously accepted price for systems with equivalent performance.
During 1986, in less than twelve months, Paragon Graphics designed, developed and demonstrated the PARAGON I Realtime Visual System (RVS). The PG-I was the first truly low cost CIG which could duplicate all the key performance features previously available exclusively on multi-million dollar systems such as 1000 line resolution, anti-aliasing and a 60hz update rate. PG-I.5, available since 1988, has been delivered in quantity to both commercial and military users. Introduced in 1990, PG-II provides vastly increased performance capabilities, including an increase in realtime scene content to 10,000 polygons, optional texture mapping, and dynamic distortion correction. Although low cost, the PARAGON systems are capable of presenting robust out-the-window scenes containing multiple moving objects (Fig. 1) and high detail target images (Fig. 2).
PARAGON systems include all the standard features associated with modern CIG systems: weighted average sub-pixel anti-aliasing, anti-aliased light points, weather effects, horizon glow, fade level detail, sun shading, transparent polygons, self-illuminating polygons, graceful system degradation, landing lights and data base management.
Planned for delivery in 1991, PG-III offers photographic texture mapping. Each photo map can support up to 256 by 256 pixels; 64 (optional 256) unique maps can be utilized per frame. The arrival of PG-III has made the performance of the most sophisticated visual systems affordable to all users.
Visual simulation had been, without a doubt, the most elusive segment in the evolution of cost-effective simulator training devices. Since the inception of simulation as a training media by Mr. Ed Link, the trend has always been toward the goal of achieving greater realism. For years, industry accepted the higher prices that accompanied higher fidelity. Other than replicating sustained "G" cues, simulation can now replicate the vehicle training in all aspects - especially when one views the visual scenes utilizing photographic texture mapping.
Unfortunately, advances in the state-of-the-art have come at a phenomenal price. During the mid-1980's, basic CIG systems have cost upwards from 1.5 million dollars, and the most sophisticated systems have cost over 5 million dollars. Now, in 1990's CIG visual systems can finally be acquired from Paragon Graphics at very significantly reduced prices, about one-tenth that of the previously established price levels. Additionally, Paragon's new low cost CIG systems include many standard capabilities that were only recently very expensive options on the most advanced systems: features such as multiple eyepoints, dozens of independently moving models.
Low cost systems are needed, and they are needed now. They have been needed ever since we discovered how to build a cockpit simulator of reasonable fidelity for less than five million dollars. A good number of manufacturers can supply an effective single or twin engine aircraft simulator for less than one million dollars. The general aviation aircraft manufacturers are delivering basic training aircraft for under one hundred thousand dollars. With regard to CIG visual systems, it seems reasonable that "low cost" be defined to mean ready-for-training systems that cost less than $100,000 per channel. Only Paragon Graphics, Inc. has successfully demonstrated that full featured visual systems are available for such a price.
Article for Publication
April 1991 issue of