Changes

A '''focal conflict''' is when a brain receives mismatching cues between eyes' [[focus]] and [[vergence]]. The effect can be unpleasant and cause eye strain. This can happen with fixed-focus biscopic displays, such as the [[Meta Quest]], [[Oculus Rift]], and [[HoloLens]].

A '''focal conflict''' is when a brain receives mismatching cues between eyes' [[focus]] and [[vergence]]. The effect can be unpleasant and cause eye strain. This can happen with fixed-focus biscopic displays, such as the [[Meta Quest]], [[Oculus Rift]], and [[HoloLens]].

Focal conflict can occur in [[virtual reality]] devices, [[augmented reality]] devices, and binocular flat focus autostereoscopic displays.  

Focal conflict can occur in [[virtual reality]] gadgets, [[augmented reality]] gadgets, and binocular flat focus autostereoscopic displays.  

Focal conflict can be encountered when viewing flat-focus [[stereogram]]s, [[3D movie]]s, or [[virtual reality]] (VR). It can cause visual fatigue and headaches after a short period of time; It is one of the main contributors to [[virtual reality sickness]]. The phenomenon can make it impossible to focus on objects close to the eye in VR, limiting the development of VR software.<ref name=facebook>{{Citation |title=Vergence-Accommodation Conflict: Facebook Research Explains Why Varifocal Matters For Future VR |url=https://www.youtube.com/watch?v=YWA4gVibKJE |language=en |access-date=2022-09-26| others=This sequence of clips is taken from Douglas Lanman's talk 'Quality Screen Time: Leveraging Computational Displays for Spatial Computing' at the 33d annual Electronic Imaging Symposium (26-30 January 2020)}}</ref>

Focal conflict can be encountered when viewing flat-focus [[stereogram]]s, [[3D movie]]s, or [[virtual reality]] (VR). It can cause visual fatigue and headaches after a short period of time; It is one of the main contributors to [[virtual reality sickness]]. The phenomenon can make it impossible to focus on objects close to the eye in VR, limiting the development of VR software.<ref name=facebook>{{Citation |title=Vergence-Accommodation Conflict: Facebook Research Explains Why Varifocal Matters For Future VR |url=https://www.youtube.com/watch?v=YWA4gVibKJE |language=en |access-date=2022-09-26| others=This sequence of clips is taken from Douglas Lanman's talk 'Quality Screen Time: Leveraging Computational Displays for Spatial Computing' at the 33d annual Electronic Imaging Symposium (26-30 January 2020)}}</ref>

== Effects ==

== Effects ==

Focal conflict is part of why VR and 3D media causes eye strain and is disorienting.<ref>{{Cite web |title=Is it normal the 3DS effect hurt my eyes? - Nintendo 3DS |url=https://gamefaqs.gamespot.com/boards/997614-nintendo-3ds/72524629 |access-date=2022-09-26 |website=gamefaqs.gamespot.com}}</ref> There is not a strong consensus on the extent of visual damage, if any, that may occur due to overexposure to vergence-focal conflict. Even though this is the case, users of classic stereoscopic devices report being unable to look at the 3D screen for a long period of time.<ref>{{Cite web |title=Is Your Nintendo 3DS Bad for Your Health? |url=https://www.pcmag.com/archive/is-your-nintendo-3ds-bad-for-your-health-262584 |access-date=2022-09-26 |website=PCMAG |language=en}}</ref>

Focal conflict is part of why VR and 3D media causes eye strain and is disorienting.<ref>{{Cite web |title=Is it normal the 3DS effect hurt my eyes? - Nintendo 3DS |url=https://gamefaqs.gamespot.com/boards/997614-nintendo-3ds/72524629 |access-date=2022-09-26 |website=gamefaqs.gamespot.com}}</ref> There is not a strong consensus on the extent of visual damage, if any, that may occur due to overexposure to vergence-focal conflict. Even though this is the case, users of classic stereoscopic gadgets report being unable to look at the 3D screen for a long period of time.<ref>{{Cite web |title=Is Your Nintendo 3DS Bad for Your Health? |url=https://www.pcmag.com/archive/is-your-nintendo-3ds-bad-for-your-health-262584 |access-date=2022-09-26 |website=PCMAG |language=en}}</ref>

== Measurement ==

== Measurement ==

==Causes==

==Causes==

===Virtual and augmented reality===

===Virtual and augmented reality===

Examples of fixed-focus biscopic devices that can cause focal conflict include the [[Oculus Quest 2]], [[HTC Vive]], [[Valve Index]] and the [[Microsoft HoloLens]]. Focal conflict can be experienced by bringing a virtual object very close to one's eyes in the headset and trying to focus on it.<ref>{{Citation |title=Vergence-Accommodation Conflict: Facebook Research Explains Why Varifocal Matters For Future VR |url=https://www.youtube.com/watch?v=YWA4gVibKJE |language=en |access-date=2022-09-22|publisher=VR Trailers & Clips|date =18 July 2020| via=YouTube|format=Video}}</ref>

Examples of fixed-focus biscopic gadgets that can cause focal conflict include the [[Oculus Quest 2]], [[HTC Vive]], [[Valve Index]] and the [[Microsoft HoloLens]]. Focal conflict can be experienced by bringing a virtual object very close to one's eyes in the headset and trying to focus on it.<ref>{{Citation |title=Vergence-Accommodation Conflict: Facebook Research Explains Why Varifocal Matters For Future VR |url=https://www.youtube.com/watch?v=YWA4gVibKJE |language=en |access-date=2022-09-22|publisher=VR Trailers & Clips|date =18 July 2020| via=YouTube|format=Video}}</ref>

Stereoscopic displays such as [[holographic display]]s and [[light field display]]s can remove the problem.<ref name="kramida" />

Stereoscopic displays such as [[holographic display]]s and [[light field display]]s can remove the problem.<ref name="kramida" />

==Mitigations==

==Mitigations==

VR and AR hardware companies often ask software developers not to show virtual content too close to the user in the devices.<ref>{{Cite web |title=Comfort - Mixed Reality |url=https://learn.microsoft.com/en-us/windows/mixed-reality/design/comfort |access-date=2022-09-22 |website=learn.microsoft.com |date=19 October 2021 |language=en-us}}</ref><ref>{{Cite web |date=2019-08-26 |title=Magic Leap Developer - Game Design: Best Practices |url=https://ml1-developer.magicleap.com/en-us/learn/guides/best-practices-in-game-design |url-status=live |archive-url=https://web.archive.org/web/20220922071934/https://ml1-developer.magicleap.com/en-us/learn/guides/best-practices-in-game-design |archive-date=2022-09-22 |access-date=2022-09-22 |website=Magic Leap Developer}}</ref> However, this is only a software mitigation and often times the effect can still be noticed.

VR and AR hardware companies often ask software developers not to show virtual content too close to the user in the gadgets.<ref>{{Cite web |title=Comfort - Mixed Reality |url=https://learn.microsoft.com/en-us/windows/mixed-reality/design/comfort |access-date=2022-09-22 |website=learn.microsoft.com |date=19 October 2021 |language=en-us}}</ref><ref>{{Cite web |date=2019-08-26 |title=Magic Leap Developer - Game Design: Best Practices |url=https://ml1-developer.magicleap.com/en-us/learn/guides/best-practices-in-game-design |url-status=live |archive-url=https://web.archive.org/web/20220922071934/https://ml1-developer.magicleap.com/en-us/learn/guides/best-practices-in-game-design |archive-date=2022-09-22 |access-date=2022-09-22 |website=Magic Leap Developer}}</ref> However, this is only a software mitigation and often times the effect can still be noticed.

==Solutions==

==Solutions==

[http://www.creal.com CREAL], a near-eye display manufacturer for AR headsets/glasses, developed a light field display technology that projects the light rays just like they exist in the real world. This way, the virtual content has a real depth, and each eye can change focus naturally between the virtual objects, from up close to infinity.

[http://www.creal.com CREAL], a near-eye display manufacturer for AR headsets/glasses, developed a light field display technology that projects the light rays just like they exist in the real world. This way, the virtual content has a real depth, and each eye can change focus naturally between the virtual objects, from up close to infinity.

[[SeeReal Technologies]], a manufacturer of displays for 3D-enabled mobile devices, claim that their displays can generate visuals that do not have fixed focus.<ref>{{Cite book|chapter-url=https://www.spiedigitallibrary.org/conference-proceedings-of-spie/6803/68030M/Large-holographic-displays-as-an-alternative-to-stereoscopic-displays/10.1117/12.766163.full|chapter=Large holographic displays as an alternative to stereoscopic displays|first1=R.|last1=Häussler|first2=A.|last2=Schwerdtner|first3=N.|last3=Leister|editor-first1=Andrew J |editor-first2=Nicolas S |editor-first3=John O |editor-last1=Woods |editor-last2=Holliman |editor-last3=Merritt |title=Stereoscopic Displays and Applications XIX |date=29 February 2008|publisher=SPIE|volume=6803|pages=219–227|via=www.spiedigitallibrary.org|doi=10.1117/12.766163|s2cid=62176480 }}</ref> The company developed the display used in the [[Takee 1]] smartphone.<ref>{{Cite web |last=Kano3D |date=2020-12-29 |title=Takee 1: The first Holographic Smartphone gets a new Update after 6 Years! |url=https://www.tridimensional.info/2020/12/takee-1-the-first-holographic-smartphone-gets-a-new-update-after-6-years/ |access-date=2022-09-28 |website=Tridimensional.info |language=en-US}}</ref> However, SeeReal's solution requires [[eye tracking]], which can limit the 3D capabilities of the displays such as the [[field of view]] of the 3D effect.{{citation needed|date=October 2022}}

[[SeeReal Technologies]], a manufacturer of displays for 3D-enabled mobile gadgets, claim that their displays can generate visuals that do not have fixed focus.<ref>{{Cite book|chapter-url=https://www.spiedigitallibrary.org/conference-proceedings-of-spie/6803/68030M/Large-holographic-displays-as-an-alternative-to-stereoscopic-displays/10.1117/12.766163.full|chapter=Large holographic displays as an alternative to stereoscopic displays|first1=R.|last1=Häussler|first2=A.|last2=Schwerdtner|first3=N.|last3=Leister|editor-first1=Andrew J |editor-first2=Nicolas S |editor-first3=John O |editor-last1=Woods |editor-last2=Holliman |editor-last3=Merritt |title=Stereoscopic Displays and Applications XIX |date=29 February 2008|publisher=SPIE|volume=6803|pages=219–227|via=www.spiedigitallibrary.org|doi=10.1117/12.766163|s2cid=62176480 }}</ref> The company developed the display used in the [[Takee 1]] smartphone.<ref>{{Cite web |last=Kano3D |date=2020-12-29 |title=Takee 1: The first Holographic Smartphone gets a new Update after 6 Years! |url=https://www.tridimensional.info/2020/12/takee-1-the-first-holographic-smartphone-gets-a-new-update-after-6-years/ |access-date=2022-09-28 |website=Tridimensional.info |language=en-US}}</ref> However, SeeReal's solution requires [[eye tracking]], which can limit the 3D capabilities of the displays such as the [[field of view]] of the 3D effect.{{citation needed|date=October 2022}}

==See also==

==See also==