Editing Virtual reality (section)

== Visual immersion experience ==

=== Display resolution ===
Minimal Angle of Resolution (MAR) refers to the minimum distance between two display pixels. At a distance, a viewer can clearly distinguish the independent pixels. Often measured in arc-seconds, MAR between two pixels has to do with the viewing distance. For the general public, resolution is about 30–65 arc-seconds, which is referred to as the spatial resolution when combined with distance. Given the viewing distance of 1m and 2m respectively, regular viewers won't be able to perceive two pixels as separate if they are less than 0.29mm apart at 1m and less than 0.58mm apart at 2m.<ref>{{Cite book|last=Davson|first=Hugh|url=https://www.worldcat.org/oclc/841909276|title=The Physiology of The Eye.|date=1972|publisher=Elsevier Science|isbn=978-0-323-14394-3|location=Burlington|oclc=841909276}}</ref>

=== Image latency and display refresh frequency ===
Most small-size displays have a refresh rate of 60&nbsp;Hz, which adds about 15ms of additional latency. The number is reduced to less than 7ms if the refresh rate is increased to 120&nbsp;Hz or even 240&nbsp;Hz and more.<ref>{{Cite web |last=Leclair |first=Dave |date=2022-09-21 |title=From 60Hz to 240Hz: Refresh Rates on Phones Explained |url=https://uk.pcmag.com/mobile-phones/142775/from-60hz-to-240hz-refresh-rates-on-phones-explained |access-date=2022-10-19 |website=PCMag UK |language=en-gb}}</ref> Participants generally feel that the experience is more immersive with higher refresh rates as a result. However, higher refresh rates require a more powerful [[graphics processing unit]].

=== Relationship between display and field of view ===
[[File:Immersive Index In Theory larger.jpg|thumb|In theory, VR represents a participant's field of view (yellow area).]]
In assessing the achieved immersion by a VR device, we need to consider our field of view ([[FOV]]) in addition to image quality. Our eyes have a horizontal FOV from about 107 or 110 degrees to the temporal side to about 60 or 70 degrees toward the nose and a vertical FOV from about 95 degrees downward to 85 degrees upward,<ref name="myths">{{cite journal | last1 = Strasburger | first1 = Hans | title = Seven myths on crowding and peripheral vision | journal = i-Perception| volume = 11 |issue=2 | year = 2020 | pages=1–45| doi = 10.1177/2041669520913052 | pmid = 32489576 | pmc = 7238452 }}</ref> and eye movements are estimated as roughly 30 deg to either side horizontally and 20 vertically. Binocular vision is limited to the 120 or 140 degrees where the right and the left visual fields overlap. With eye movements, we have an FOV of roughly 300 degrees x 175 degrees with two eyes, i.e., approximately one third of the full 360-deg sphere.