Accessibility in VR: Head Height



Greetings Internet! My name is Brian Van Buren, and I am the Narrative Designer at Tomorrow Today Labs, a VR studio based in Seattle. I am also a wheelchair user — spinal cord injury at the L2/L3 level for those in the know — and am unable to walk or stand. This is the first post of a series focusing on ways to make VR experiences accessible for disabled/mobility impaired users.

VR has tremendous potential to change the way people work, learn and play, but with this unique medium comes unique challenges. Making sure that designers and developers are solving them at this early stage is paramount. My goal in this Accessibility in VR series is to identify the challenges and show ways I and others have attempted to solve them. This post will focus on something unique to room-scale VR: head height.

Head Height Tracking

Before VR, we designed game environments and interactions knowing we had control over the view angle and interaction models. In first-person games you controlled the viewing angle for the player; you could set the view angle, take control over the camera when necessary, and design the space and interactions around that.

While this works fine for the classic monitor and mouse-and-keyboard/controller configuration, in VR it is problematic. We don't have control of the camera any more; users can look at whatever they want whenever they want. Taking control of the camera in VR can make users disoriented and nauseous. With the HTC Vive, which uses sensors to determine the head height of the user, we don't even have control of the camera height.

With the Vive, the head height (and controller location) of the user is automatically tracked, placing the "camera level" of the user at something closely approximating their natural head height. The view of the user in the HMD is accurately placed and tracked within the environment, as are the controllers.

Accurate head height/controller placement creates a high degree of immersion; that magic state where you believe that the artificial space is real and that you have presence within it. Since immersion is key to creating engaging VR experiences, and having your natural head height helps increase immersion, this is a great thing, right? Well...

When creating room scale VR spaces, you cannot assume the head height of your user.

Users come in all shapes and sizes; some tall, some short, some seated. Since the user interacts in a room-scale VR space with a realistic approximation of their body, the physical dimensions of both the space and the user matter. Depending on the design of the space and the dimensions/limitations of that user, they may not be able to interact with the space in an ideal fashion, if at all.

Take the Job Simulator Demo for example. In the cooking level, one of the tasks asks the user to put ingredients into a pot on a stove, which is placed at about the same height as a real-life stove top. It was difficult for me to put objects in the pot, and just like in real life I couldn't see into it from my seated perspective. However, in real life I would prop myself up using a counter top to look in; doing that in VR ends up with me doing this.

Standing vs. Seated Perspectives

The following gifs show the differences in interacting with objects at different head heights. In the first, the user is interacting with the environment from a standing perspective (in our own NewtonVR sandbox experience).

This next gif shows a user interacting with the same environment from a seated perspective.

From the seated perspective, it is difficult to see into the drawer, but easy to interact with objects on the floor. From the standing perspective, seeing into the drawer is easy, but the user must duck down to interact with the floor objects. So while the space is accessible from a seated perspective, it is not ideal; neither is forcing a standing user to bend over or kneel down, especially if done often.

So what do we do ensure an accessible experience for all users when we can't control their physical dimensions? Here are some different ways to create head height accommodations in VR.

Adjustable Head Height

The most obvious accommodation is to allow the user the option to adjust the head height. This allows the user to set a comfortable head height that gives them access to the environment without requiring changes to the design of the space. This is not only important for seated users, but all short users - if you've ever seen a 5-year old try to function in a room scale VR space you know what I'm talking about.

In this example from Hover Junkers, the head height is fully adjustable. Hover Junkers is a competitive shooter where the player must duck behind walls to avoid attack, so creating an accurate representation of the body model through head height tracking is important.

As a design solution, it is functional and fits within the game world and concept — you're being measured for a casket, so the game needs to know how tall you are. Also, the head height adjustment option was added and tested early in development.

Recently, Job Simulator added a "shorter human" mode that increases the head height by a specific amount; it makes the head height taller but is a one-size-fits-all solution. The design of the option — a switch — is elegant and simple, and has a real-world analog that is common and understandable.

Though the feature was added post-release, the solution works for the most part. It does illustrate the need to identify and fix accessibility issues in the design phase, because users will encounter them eventually.

Adjustable head height is a good accommodation, but can be problematic for some games. In a multiplayer shooter, for example, if the hit box for the player is set to a body model, that does the hit box change when the head height changes? Players may exploit this by choosing the smallest body model possible as to avoid being hit.

When changing head height make sure that the Vive controllers also change height to match. Increasing head height without pairing the controllers may fix visual problems but won't fix interaction problems. Also, raising the head height may put floor objects out of reach, so dropped items may become inaccessible.

Designing Accommodating Spaces

As a designer, I'm partial to design-based solutions. The gifs to follow are from an unreleased prototype from Tomorrow Today Labs. The ping pong ball dispenser went through a few iterations before we came to this one. Initially, the balls were dispensed directly onto the floor, and being small objects they were hard to grab and the repeated kneeling/standing needed to perform the task became uncomfortable quickly. The solution was to dispense the balls into a raised container, but where should it go?

From the seated perspective, the container is about shoulder height.

From the standing perspective, the container is about waist height.

The space is comfortable for a standing user without being difficult for the seated user. This is an example of Universal Design; designing so that all users can function within an inclusive space without that inclusiveness being obtuse. Designing accommodating spaces requires forethought and planning, but is a more robust solution than adding it in after the fact.

Bypassing Content

Sometimes, the design of the experience is based around a set of actions that cannot be performed from a seated position. Crawling, lying prone, reaching objects set at a great height, crouching to hide behind chest-high walls — these actions may not be possible for the seated user. In other instances, creating an accurate representation of a real-world space may trump accessibility needs; take it from me, the real world isn't always accessible.

As a designer, you must ask yourself why these actions are required for your experience. Is there another way to maintain/increase immersion without forcing the user to perform the physical actions? Is this mechanic so central to your design that without it the experience is lessened/impossible? Is the accuracy of presenting a real-world space more important than a user's ability to utilize that space?

In Unseen Diplomacy, there is a limited mobility option that allows the user to bypass certain content that cannot be completed from a seated position. If the user cannot advance through the experience, nothing else about it really matters, so providing a bypass option is better than nothing. This interview with designer Katie Good about the accessibility option in Unseen Diplomacy details her thoughts about accessibility design in VR.

When Accessibility is Required

The above examples come from the gaming world, but VR has tremendous potential in other fields. The entertainment field is the first major adopter, and as VR movies and interactive field trips become more popular even more types of experiences will become available. Also, educational and training software in VR has huge advantages in that real-world spaces and actions can be mimicked in safe environments and at lower costs.

In many countries software used in a business setting or for government use is required to have accessibility options. In the United States, for example, the Americans with Disabilities Act is the law regarding accommodation for and discrimination against disabled people. "The law forbids discrimination when it comes to any aspect of employment, including training", so training software used in the United States should be designed with reasonable accessibility options. Microsoft productivity software has very robust accessibility support, so look to them and others for role models on how to make business software accessible.

Final Thoughts

Creating accessible VR spaces to operate in is not difficult. It requires forethought, planning and testing, and sometimes requires creators to make hard choices. But above all it needs awareness within the development/design community.

VR spaces aren't simply meant to be traversed or navigated through; they are meant to be inhabited, by everyone and anyone.

I hope you enjoyed this Accessibility in VR post, and have learned as much from reading it as I did from writing it. Questions? Suggestions? Ideas for future topics in this series? Post them in the comments below, and make sure to follow me on Twitter. Thanks for reading, and see you around the Internet!

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Brian Van Buren

Narrative Designer @ Tomorrow Today Labs. Designer, Writer, Utility Infielder. Former gigs @ Nintendo, Sierra Games and 17-BIT. Accessibility Design advocate and consultant. Also, I have a cat.