Oculus Rift S uses a single display panel and fixed lenses. Unlike the original Rift and the upcoming Oculus Quest, it does not have a mechanical adjustment of the distance between the lenses.
This means that the recently announced Facebook Rift S corresponds to a smaller interpupillary distance range (IPDs). Facebook has confirmed the range of IPDs that “best” fits into Rift S. by comparing this range with the largest publicly available set of IPDs that we can find. Thus, it was found almost universal IPD, which suits most users.
What is IPD?
IPD is the interpupillary distance, i.e. the distance between the pupils of the left and right eyes.
Some VR headsets, such as the original Rift and HTC Vive, allow you to mechanically adjust the distance between the lenses to match (at least approximately) the distance between the eyes. Others have fixed lenses, like most Windows MR headsets and over four million PSVR headsets sold so far.
If the distance between the lenses of a headset is too different from your IPD, research shows that some people may feel blurring, eye strain, distortion, and this may even make some users feel bad. You will also see the virtual world at the wrong scale, but setting up IPD software can compensate for this.
IPD-range Rift S
Facebook confirmed that the range of separation of lenses for Quest is 58-72mm.
For Rift S and Go lenses are fixed at 63.5 mm. This means that Quest “is best suited for users with an interpupillary distance of 56mm and 74mm,” and Rift S and Go “are best suited for users with 61.5 and 65.5 mm,” according to Facebook.
We looked at the IPD ranges described above in more detail to better understand how these headsets fit the range of face shapes and sizes around the world. The largest publicly available IPD measurement dataset we know about is ANSUR II. ANSUR is a collection of data collected by the US Army from 93 units from over 6,000 active and reservist personnel. One of these measures is the interpupillary distance.
We loaded the data and used it to show the “best” IPD fit of the Oculus headsets. The IPD median is 63.5 mm, but it should be noted that IPD correlates with age and gender. The subjects of this dataset are adults, so it is not representative of children. In addition, since the data set contains more men than women, we divided it to the floor.
The data show that the mechanical setting of IPD Quest makes it the “best” headset for 99% of men and 93% of women, unfixed Rift S lenses “resemble” only for 46% of men and 43% of women.
A Facebook representative suggested the following:
“Perception and comfort will vary from person to person and depend on anatomy, and some people may have a higher tolerance for experience (for example, if they go beyond the“ better ”range, they can still use the headset and enjoy it).
We talked to people with IPDs outside the “optimal” range who tried Rift S and did not report problems. Many of them use the fixed IPD Oculus Go without problems. If your IPD is at the extremes, you may have problems, so if you are thinking about purchasing Oculus Rift S, you can measure your IPD before you make a purchase. This can be done using applications from the App Store and Google Play, which allow you to measure this indicator directly from your smartphone.
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