Systems for producing the extra-cockpit visual scene have been proposed and constructed for almost as long as flight simulators themselves. However, realistic and flexible visual attachments are a fairly recent development. Due to the large number of visual systems which have been invented, only some of the more successful ones can be mentioned here.
The point-light source projection, or shadow graph, method enjoyed popularity in the 1950's, especially for helicopter simulators. A series of simulators using this method of visual display were produced by Giravions Dorand in France including an ab initio hovering trainer produced by Shorts of Belfast in 1955. Simulators on this pattern were also built in the United States, but the shortcomings of the shadow graph system seems to have limited the success of the concept. The first visual systems achieving widespread use on civil aviation simulators were based on the scale model and television camera method, although methods based on film and anamorphic optical systems have also met with success for more restricted applications. Serious development of closed-circuit television visual systems began in the mid 1950's with monochrome systems being produced by Curtiss-Wright, Link (then the Link division of General Precision) and General Precision Systems (formerly Air Trainers and Air Trainers Link Limited). The first colour system was produced by Redifon in 1962. Television based visual systems have under gone a steady development since then, with a large part of the effort being devoted to improved methods of image display.
The first computer image generation systems for simulation were produced by the General Electric Company (USA) for the space programme. Early versions of these systems produced a patterned "ground plane" image, while later systems were able to generate images of three-dimensional objects. Progress in this technology has been rapid and closely linked to developments in digital computer hardware technology. Current systems available from major simulator manufacturers are able to produce full colour images with scene contents of several thousand polygons and point-light sources. A parallel development has taken place in night-only computer image generation systems; these use the calligraphic or stroke-writing, rather than the raster scan method of display, which enables a superior reproduction of light points. The first of these systems was produced by the McDonnell-Douglas Electronics Corporation in 1971 and called Vital II.
Current systems, can produce images of night, dusk, and daylight, they can run at two rates 60Hz for daylight, or 40Hz for dusk/night. Per second they can sustain continuous 1.8M polygons, with a 1.2Giga pixel fill rate and 360000 calligraphic lights, (approx. 30000 polygons 15000 calligraphic lights and 7500 raster lights per frame). 16 sub pixel antialiasing, texturing, Phong shading, transparency, fog, layered fog, bump mapping and depth buffering are all available simultaneously for all pixels and polygons, at the sustained rate. A typical commercial system has a viewable area of 4M pixels, spread across three projectors (1.5M pixels each) though up to 5 can be used, and a texture map memory of 1 GB.
A Computer generated view of JFK Airport at dusk © E&S.
A Computer generated view showing use of texture © E&S.
For pictures of modern aircraft flight simulators & visual systems, go to my simulator pictures page.
Aeroplane Maintenance & Operation Series, Vol. 8.
The Link Trainer.
50 Years of Flight Simulation.
Conference Proceedings April 1979.
Edited by J.M.Rolfe & K.J.Staples.
ISBN. 0 521 35751 9 paperback.