Editing Flight simulator (section)

=== Visual system ===
[[File:DA42-Simulator at Horizon SFA.jpg|thumb|A wide angle cylindrical display]]

Outside view from the aircraft is an important cue for flying the aircraft, and is the primary means of navigation for [[visual flight rules]] operation.<ref>Section 91.155 14 CFR Part 91 - General Operating and Flight Rules - FAA</ref> One of the primary characteristics of a visual system is the [[field of view]]. Depending on the simulator type it may be sufficient to provide only a view forward using a flat display. However, some types of craft, e.g. [[fighter aircraft]], require a very large field of view, preferably almost full sphere, due to the manoeuvres that are performed during air combat.<ref name="barretteModernAirCombat1985">{{cite Q|Q112840484}}</ref> Similarly, since [[helicopter]]s can perform hover flight in any direction, some classes of helicopter flight simulators require even 180 degrees of horizontal field of view.<ref>Appendix 1 to CS FSTD(H).300, 1.3 Visual system, requirement b.3</ref>

There are many parameters in visual system design. For a narrow field of view, a single display may be sufficient, however typically multiple projectors are required. This arrangement needs additional calibration, both in terms of distortion from not projecting on a flat surface, as well as brightness in regions with overlapping projections.<ref name="renoFullFieldView1989">{{Cite Q|Q112790735}}</ref> There are also different shapes of screens used, including cylindrical,<ref name="cameronDevelopmentImplementationCosteffective2016">{{cite Q|Q112812641}}</ref> spherical<ref name="renoFullFieldView1989" /> or ellipsoidal. The image can be projected on the viewing side of the [[projection screen]], or alternatively "back-projection" onto a translucent screen.<ref name="bestM2DARTRealImage1999">{{cite Q|Q112840621}}</ref> Because the screen is much closer than objects outside aircraft, the most advanced flight simulators employ [[cross-cockpit collimated display]]s that eliminate the [[parallax]] effect between the pilots' point of view, and provide a more realistic view of distant objects.<ref name="pierceImplicationsImageCollimation1998">{{Cite Q|Q112793062}}</ref>

An alternative to large-scale displays are [[virtual reality]] simulators using a [[head-mounted display]]. This approach allows for a complete field of view, and makes the simulator size considerably smaller. There are examples of use in research,<ref name="oberhauserVirtualRealityFlight2017" /> as well as certified {{abbr|FSTD|Flight Simulator Training Device}}.<ref name="easavr2021">{{Cite press release |title=EASA approves the first Virtual Reality (VR) based Flight Simulation Training Device |date=2021-04-26 |publisher=[[European Union Aviation Safety Agency]] |url=https://www.easa.europa.eu/en/newsroom-and-events/press-releases/easa-approves-first-virtual-reality-vr-based-flight-simulation |access-date=2025-02-10}}</ref>

==== Contribution to modern computer graphics ====
Visual simulation science applied from the visual systems developed in flight simulators were also an important precursor to three dimensional computer graphics and [[Computer Generated Imagery]] (CGI) systems today. Namely because the object of flight simulation is to reproduce on the ground the behavior of an aircraft in flight. Much of this reproduction had to do with believable visual synthesis that mimicked reality.<ref>{{cite book |last1=Rolfe|first1= JM |last2= Staples|first2= KJ |title=Flight Simulation Cambridge Aerospace Series No 1 |date=May 27, 1988 |publisher=Cambridge University Press |isbn=978-0521357517}}</ref> Combined with the need to pair virtual synthesis with military level training requirements, graphics technologies applied in flight simulation were often years ahead of what would have been available in commercial products. When CGI was first used to train pilots, early systems proved effective for certain simple training missions but needed further development for sophisticated training tasks as terrain following and other tactical maneuvers. Early CGI systems could depict only objects consisting of planar polygons. Advances in algorithms and electronics in flight simulator visual systems and CGI in the 1970s and 1980s influenced many technologies still used in modern graphics. Over time CGI systems were able to superimpose texture over the surfaces and transition from one level of image detail to the next one in a smooth manner.<ref>{{Cite journal |last=Yan |first=Johnson |date=August 1985 |title=Advances in Computer-Generated Imagery for Flight Simulation |url=https://ieeexplore.ieee.org/document/4056245 |journal=[[IEEE Computer Graphics and Applications]] |volume=5 |issue=8 |pages=37–51 |doi=10.1109/MCG.1985.276213 |s2cid=15309937 |via=|url-access=subscription }}</ref>  Real-time [[computer graphics]] visualization of virtual worlds makes some aspects of flight simulator visual systems very similar to [[game engine]]s, sharing some techniques like [[Level of detail (computer graphics)|different levels of details]] or libraries like [[OpenGL]].{{r|allerton2009|p=343}}  Many computer graphics visionaries began their careers at Evans & Sutherland and Link Flight Simulation, Division of Singer Company, two leading companies in flight simulation before today's modern computing era. For example, the Singer Link Digital Image Generator (DIG) created in 1978 was considered one of the worlds first CGI system.<ref>{{cite web |last1=Carlson |first1=Wayne |title=Computer Graphics and Animation: a retrospective review |date=20 June 2017 |url=https://ohiostate.pressbooks.pub/graphicshistory/chapter/13-2-singer-link/ |page=13.2}}</ref>