Technically this would be possible to overcome with a light field display. Light field displays are currently very far off from becoming commercially viable.

Well, wether to product is viable or not, that's what Magic Leap is trying to deliver.

You could approximate this using a standard display if you could dynamically track and respond to focal depth.

That might be harder than getting a functional light field display, though.

Much easier, we have the tech in ophthalmology and adaptive lenses that are used in cellphone cameras.

Out of curiosity, what would the tech stack look like?

What I was picturing was: - LCD display - Patterned IR image projected onto eye - Camera to read IR image on the back of retina, to figure out current focal length of cornea - Realtime chip to adjust LCD display based on focal depth, to simulate light field image.

... The real issue is that response latency would have to be <10ms probably to avoid being disorienting.

Isn't it more likely to be lag and inner ear related, not related to light angles? Why do you think it's light angles?

It's hotly debated, and the literature is often in conflict as to the exact cause of simulator sickness. Regardless of the exact reason, sickness of roughly half the population appears to be somehow fundamental to VR.

Here's some interesting reading:

https://en.wikipedia.org/wiki/Simulator_sickness

https://news.ycombinator.com/item?id=5265985

> In a study conducted by U.S. Army Research Institute for the Behavioral and Social Sciences in a report published May 1995 titled "Technical Report 1027 - Simulator Sickness in Virtual Environments", out of 742 pilot exposures from 11 military flight simulators, "approximately half of the pilots (334) reported post-effects of some kind: 250 (34%) reported that symptoms dissipated in less than 1 hour, 44 (6%) reported that symptoms lasted longer than 4 hours, and 28 (4%) reported that symptoms lasted longer than 6 hours. There were also 4 (1%) reported cases of spontaneously occurring flashbacks."

Simulator Sickness in Virtual Environments (PDF): http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA295861

Some interesting quotes from the report:

Expected incidence and severity of simulator sickness in virtual environments

> In an analysis of data from 10 U.S. Navy and Marine Corps flight simulators, Kennedy, Lilienthal, Berbaum, Baltzley, and McCauley (1989) found that approximately 20% to 40% of military pilots indicated at least one symptom following simulator exposure. McCauley and Sharkey (1992) pointed out that pilots tend to be less susceptible to motion sickness than the general population due to a self-selection process based on their resistance to motion sickness. Since VE technologies will be aimed at a more general population, such selection against sickness may not occur. Thus, McCauley and Sharkey suggested that sickness may be more common in virtual environments than in simulators.

Findings

> Although there is debate as to the exact cause or causes of simulator sickness, a primary suspected cause is inconsistent information about body orientation and motion received by the different senses, known as the cue conflict theory. For example, the visual system may perceive that the body is moving rapidly, while the vestibular system perceives that the body is stationary. Inconsistent, non-natural information within a single sense has also been prominent among suggested causes.

> Although a large contingent of researchers believe the cue conflict theory explains simulator sickness, an alternative theory was reviewed as well. Forty factors shown or believed to influence the occurrence or severity of simulator sickness were identified. Future research is proposed.

Vection

> One phenomenon closely involved with simulator sickness is that of illusory self-motion, known as vection. Kennedy et a1. (1988) stated that visual representations of motion have been shown to affect the vestibular system. Thus, they conclude that the motion patterns represented in the visual displays of simulators may exert strong influences on the vestibular system. Kennedy, Berbaum, et al. (1993) stated that the impression of vection produced in a simulator determines both the realism of the simulator experience and how much the simulator promotes sickness. They suggested that the most basic level of realism is determined by the strength of vection induced by a stimulus. For a stimulus which produces a strong sense of vection, correspondence between the simulated and real-world stimuli determines whether or not the stimulus leads to sickness. Displays which produce strong vestibular effects are likely to produce the most simulator sickness (Kennedy, et al., 1988). Thus, Hettinger et al. (1990) hypothesized that vection must be experienced before sickness can occur in fixed-base simulators.

> While viewing each of three 15-minute motion displays, subjects rated the strength of experienced feelings of vection using a potentiometer. In addition, before the first display and after each of the three displays, the subjects completed a questionnaire which addressed symptoms of simulator sickness. Of the 15 subjects, 10 were classified as sick, based on their questionnaire score. As for vection, subjects tended to report either a great deal of vection or none at all. In relating vection to sickness, it was found that of the 5 subjects who reported no vection, only 1 became sick; of the remaining 10 subjects who had experienced vection, 8 became sick. Based on their results, Hettinger et al. concluded that visual displays that produce vection are more likely to produce simulator sickness. It is also likely that individuals who are prone to experience vection may be prone to experience sickness. It was mentioned earlier in this report that a wider field- of-view produces more vection and, thus, is believed to increase the incidence and severity of sickness (Kennedy et al., 1989). Anderson and Braunstein (1985), however, induced vection using only a small portion of the central visual field and 30% of their subjects experienced motion sickness.

Take these studies with a grain of salt though, as display technology, IMUs, external tracking and more importantly computing power are magnitudes better than what was available in 1995.

Certainly good points. It also might be a mistake to discount studies performed under controlled conditions, though. If the cause of simulator sickness is illusory motion, then the relatively crude technologies available in 1995 may have been sufficient to induce the same effect we're observing today.

I've never met anyone who gets sick based entirely off vergence-accommodation conflict. I've certainly talked to people who claimed it was an issue but would happily go to a 3d film so I assume they were misattributing the cause of their sickness. Maybe having the peripherals line up for 3d films is enough.

I'd be interested to hear some testimonials on how it affects people though. One of the interesting things about VR is finding out the myriad of different ways people are sensitive to small phenomena.

I'll chime in on this:

I own a Vive, and get sick using that after half an hour maybe (even though it's not too bad and I can keep using it), and it takes me a few hours to "reset" afterwards.

I don't get sick in 3D movies (but I don't enjoy them, and never choose to see one in 3D if there's an alternative.

The reason I don't get sick in 3D movies I assume is because it's still just a screen, and any head movement I make is still 100% "responsive", with no delay or mismatch.

Edit: Sorry, I read your response a bit lazily. Yes, it's not related to vergence-accommodation, at least not exclusively.