Vergence-accommodation conflict: Difference between revisions
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* '''Fixed-focus HMDs''': Nearly all consumer VR and many AR headsets use internal display screens (like OLED or LCD) viewed through lenses. These lenses create a [[virtual image]] of the screens, making them appear to be located at a fixed focal distance, typically between 1.3 and 2 meters (though this varies).<ref name="Kreylos2013HMD">{{cite web |last=Kreylos |first=Oliver |title=Head-mounted Displays and Lenses |url=http://doc-ok.org/?p=1360 |website=Doc-Ok.org |date=2013-07-24}}</ref> Consequently, viewers must accommodate (focus their eyes) to this fixed plane to see a sharp image, regardless of the perceived depth of virtual objects. However, stereoscopic rendering creates virtual objects that appear at various depths by presenting slightly different images to each eye, requiring the viewer's eyes to converge or diverge (vergence). Objects rendered virtually nearer than the fixed focal plane induce a ''positive VAC'' (eyes converge more than they accommodate), while objects rendered virtually farther induce a ''negative VAC'' (eyes converge less than they accommodate).<ref name="Shibata2011">Shibata T, Kim J, Hoffman D M, Banks M S. (2011). “The zone of comfort: Predicting visual discomfort with stereo displays.” ''Journal of Vision'', 11 (8): 11. doi:10.1167/11.8.11. PMC 3369815. https://pmc.ncbi.nlm.nih.gov/articles/PMC3369815/</ref> | * '''Fixed-focus HMDs''': Nearly all consumer VR and many AR headsets use internal display screens (like OLED or LCD) viewed through lenses. These lenses create a [[virtual image]] of the screens, making them appear to be located at a fixed focal distance, typically between 1.3 and 2 meters (though this varies).<ref name="Kreylos2013HMD">{{cite web |last=Kreylos |first=Oliver |title=Head-mounted Displays and Lenses |url=http://doc-ok.org/?p=1360 |website=Doc-Ok.org |date=2013-07-24}}</ref> Consequently, viewers must accommodate (focus their eyes) to this fixed plane to see a sharp image, regardless of the perceived depth of virtual objects. However, stereoscopic rendering creates virtual objects that appear at various depths by presenting slightly different images to each eye, requiring the viewer's eyes to converge or diverge (vergence). Objects rendered virtually nearer than the fixed focal plane induce a ''positive VAC'' (eyes converge more than they accommodate), while objects rendered virtually farther induce a ''negative VAC'' (eyes converge less than they accommodate).<ref name="Shibata2011">Shibata T, Kim J, Hoffman D M, Banks M S. (2011). “The zone of comfort: Predicting visual discomfort with stereo displays.” ''Journal of Vision'', 11 (8): 11. doi:10.1167/11.8.11. PMC 3369815. https://pmc.ncbi.nlm.nih.gov/articles/PMC3369815/</ref> | ||
* '''[[3D television|3D Cinema and Television]]''': VAC also occurs here, but symptoms are often milder. The screen is typically farther away, the [[Field of view|field of view]] is smaller, and content creators can limit disparities to keep virtual objects within a "zone of comfort" relative to the screen distance.<ref name="ISO2015">International Organization for Standardization. (2015). ''ISO 9241‑392: | * '''[[3D television|3D Cinema and Television]]''': VAC also occurs here, but symptoms are often milder. The screen is typically farther away, the [[Field of view|field of view]] is smaller, and content creators can limit disparities to keep virtual objects within a "zone of comfort" relative to the screen distance.<ref name="ISO2015">International Organization for Standardization. (2015). ''ISO 9241‑392:2015 - Ergonomics of human‑system interaction – Part 392: Ergonomic requirements for the reduction of visual fatigue from stereoscopic images''. https://www.iso.org/standard/60317.html</ref> | ||
* '''[[Optical see-through display|Optical See-Through (OST) AR]]''': In OST AR glasses, virtual images (often at a fixed focus) are overlaid onto the real world. This creates a conflict not only between vergence and accommodation for virtual objects but also a potential mismatch between focusing on real-world objects at various distances and the fixed focus of the virtual overlay. This can introduce depth discontinuities, reduce the perceived registration accuracy of virtual objects, and cause discomfort.<ref name="Zhou2021">Zhou Y, Li X, Yuan C. (2021). “Vergence‑accommodation conflict in optical see‑through display: Review and prospect.” ''Results in Optics'', 5: 100160. doi:10.1016/j.rio.2021.100160. https://doi.org/10.1016/j.rio.2021.100160</ref> | * '''[[Optical see-through display|Optical See-Through (OST) AR]]''': In OST AR glasses, virtual images (often at a fixed focus) are overlaid onto the real world. This creates a conflict not only between vergence and accommodation for virtual objects but also a potential mismatch between focusing on real-world objects at various distances and the fixed focus of the virtual overlay. This can introduce depth discontinuities, reduce the perceived registration accuracy of virtual objects, and cause discomfort.<ref name="Zhou2021">Zhou Y, Li X, Yuan C. (2021). “Vergence‑accommodation conflict in optical see‑through display: Review and prospect.” ''Results in Optics'', 5: 100160. doi:10.1016/j.rio.2021.100160. https://doi.org/10.1016/j.rio.2021.100160</ref> | ||