What Is Vergence-Accommodation Conflict and How Can Developers Tackle It?

VR is a rapidly changing technology. As industry leaders strive to stake their claim in the brave new world of the metaverse, there is continued development in many of the restrictions users experience while using VR. One such area is vergence-accommodation conflict.

Recent research carried out between Meta Reality Labs and Kent State University explores this problem in-depth, and it looks as though a possible solution may have been found. 

But what exactly is vergence-accommodation conflict, and how can it be solved?

Let’s pull focus and learn more about this interesting topic.

What Is Vergence-Accommodation Conflict?

Vergence-Accommodation Conflict (VAC) is an issue that has been dogging the VR industry for a while. The problem is that all consumer headsets that have been released so far render images through stereoscopy. This creates a 3D image that requires both eyes to converge so that stereo images can be formed; however, it does not accommodate the reflexes of individual eyes which adjust to focus on the light within varying depths of field.

Ordinarily, when viewing images naturally, both vergence and accommodation reflexes occur simultaneously; however, while using VR, there is a disconnect as the eyes converge as required, but the accommodation stays the same as there is no change in the depth of where the light is coming from. 

VAC, therefore, makes it harder to focus on things that are displayed up-close, restricts full immersion, and leads to eye strain and visual fatigue. In addition, users may often have the lingering effects of VAC for a time after the headset is removed. These are big problems when it comes to trying to create an immersive experience where users will spend considerable time. 

Solving VAC

Over the years, there have been several attempts at rectifying VAC. This includes experiments aimed at developing varifocal headsets that work with both reflexes. Until now, a workable solution that is affordable enough for consumer headsets has not been found.

Possible solutions have included the use of liquid crystal lenses that allow for a change in focal length when there is an adjustment in voltage. So far, this solution has only worked with smaller lenses. This is because the larger the lens is, the slower the switch in focus speed will be.

For a contemporary consumer headset, these dynamic focus lenses need to be large enough and have a low switching time. 

Now, it seems there is a solution. Developers have potentially created a large enough dynamic focus liquid crystal lens that has phase resets. These phase resets are comparable to the rings found on a Fresnel lens; however, where the Fresnel’s segments minimise the width of the focal length, the segments in these new dynamic lenses are each powered individually to allow for rapid focal length switching.

This topic was discussed by lead researcher Amit Kumar Bhowmick at this year’s SID Display Week Conference which took place recently. 

Focusing on Improved Immersion

So, what does this innovation mean for future headsets? Time will tell, but hopefully, it’s a technology that will be rolled out in the near future making the immersive experience more comfortable and virtual worlds more habitable. Let us know what you think in the comments below. 

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