Why Focal Rivalry Is the Biggest Challenge to Mixed Reality Adoption Today

MR has a believability problem created by the fact that our eyes cannot naturally integrate real and virtual content into a genuine mixed reality. The main issue is that virtual content exists only on one focal plane and our eyes cannot be fooled by clever software alone. This creates a phenomenon known as “focal rivalry.” While the industry continues to announce new augmented/mixed reality experiences, mixed reality will never deliver its full potential if this fundamental issue is not addressed.

Why Focal Rivalry Matters

Focal rivalry manifests itself when we’re seeing real and virtual objects together and the wrong things are in focus. In May 2019, a research team at the University of Pisa conducted a study exploring how focal rivalry affects people’s performance when using AR to complete precision tasks. It found that accomplishing an AR-assisted task where content is within two meters (about 6 feet) of the person and requires a high level of precision may not be feasible with existing technology.

Microsoft’s advice to HoloLens content developers explains the issue and acknowledges the constraint in some detail. Microsoft suggests that designers should attempt to structure content scenes to encourage users to interact one meter or farther away from the content. It also recommends to not require users to rapidly switch from near-focus to far-focus as this can cause visual discomfort and fatigue.

The inability to bring content within arm’s reach and meaningfully and seamlessly engaging with content at any focal point is holding mixed reality back. At a consumer level, it makes mixed reality feel artificial, when it is used for precision tasks – such as surgery or engineering – it will limit the usefulness of the technology. Leaving focal rivalry unresolved will hinder the development of mixed reality applications and will ultimately impede its uptake.

Why Has Focal Rivalry Not Been Solved?

Over the years MR headset manufacturers have continued to improve in computing power, screen resolution and software. While these developments have made drastic improvements to the experience, they have not solved this fundamental problem. This is because focal rivalry requires an ophthalmic solution between our eyes, the digital overlay, and the real world.

The focus on upgrading software and computer hardware has resulted in the optical interface being an under-represented area of innovation. Yet, as developers build enterprise applications that require content to be viewed within arm’s reach, OEMs are starting to realise that they will need dynamic optical systems to properly integrate and manipulate the real and virtual worlds.

How Can We Address the Problem?

There are 23 visual cues that make up our natural perception of 3D space in the real world. Both VR and AR struggle to deliver a fully immersive, realistic experiences because they do not fully engage with all of them. Eighteen of these can be dealt with by upgrading software and hardware, but dynamic optical systems hold the key to the remaining five and delivering truly immersive and believable experiences. By addressing Chromatic Aberration, Accommodation, Spherical Aberration, Stiles Crawford Effect, and Vergence Accommodation, we can bring a step change in immersion and realism.

Dynamic lens systems help engage our natural visual cues and allow virtual content to be accurately and convincingly placed in the real world, allowing people to work or play effectively in a genuine mixed reality world. They are a real solution to serious problems which prevent mixed reality from reaching its market potential.

How Close Are We to Solving This Problem?

There are several possible solutions in the works, and it’s looking very promising. Even though these solutions will not be on the market tomorrow, as OEM’s understanding of the importance of the optical interface grows, I believe that one day, all but the cheapest headsets, will include some form of dynamic optics.