As Google’s UX engineer working on Daydream and Tango, Mary Cassin knows a thing or two about what makes the optimal VR/AR experience.
With VR adoption growing, we’re learning new things every day about what makes a great and comfortable user experience. Google has vast resources to learn from its users and afford the odd pitfall along the way – but few of us have such a luxury.
Over the coming years, best practices are sure to adapt, but Cassin has shared her current findings on what could make or break your VR/AR project.
The first point should be obvious – if users aren’t comfortable, they’ll leave. Users may not return and at this stage in VR/AR development, bold early creators carry the weight of proving content is comfortable and worthwhile. Failure damages the reputation of the whole industry.
Considering the depth of objects and where users will focus is more important than ever for VR. Eyes will naturally converge on the objects closest to them and the background will be blurred. To avoid eye strain and migraines, these objects must be at least an arm’s length away and multiple objects should not be spaced too far apart.
“With VR, you have to be very careful about not having the player focus on multiple objects that are far apart from each other,” explains Cassin. “It becomes distracting and very uncomfortable.”
A common pitfall creators fall into when building VR/AR is going for 360-degree experiences. Most people will experience content sat down and won’t always have a swivel chair, or want to have to spin around. “Most people will do the whole Iron Man, 360-degree UI the first time they do VR,” jokes Cassin. “Then they realise the person can’t use half the UI.”
Cassin recommends keeping the field of view to 70-degrees with interactivity occurring in just 30-degrees of the space. Rendering a smaller area may also help with keeping a high level of performance. Daydream’s UI is one example of these principles in action:
A minimum of 60 FPS should be targeted in order to reduce chances of nausea – increasing to 90 FPS for 6DoF (6 Degrees of Freedom) content. Dropping slightly below this won’t make a lot of difference, but this should be the target.
Nausea has plagued many early VR/AR titles for a variety of reasons, and some people are just more naturally susceptible than others in the same regard as some people get more seasick. The horizon in VR/AR should always be kept stable, and speed kept to a constant pace.
Cassin had some more advice when it comes to the player’s environment for a comfortable experience which encourages interaction. The first is not to place the player on an edge such as a cliff if you want interaction. Most will just stare down instead. “Edges can be a very powerful tool, but if you’re trying to get someone to interact with the UI in front of you then all they’ll be thinking is ‘Oh my god, I’m stood on an edge’,” explains Cassin.
Getting the right amount of space is also important. You shouldn’t box the player in – unless part of certain experiences such as a car – but you also shouldn’t put the player in the middle of nowhere with little going on. Cassin, as many will have, says she’s too often just dropped things in a large, empty plane.
Unless for a flying experience or similar, dropping the player into an experience with no floor is also not advisable.
One example of an AR app which takes many of these principles into account is Tango app Woorld. During a demo of it, Cassin highlights the fact it uses text and visual cues to encourage physical movement such as stepping forward (which, unless told, players otherwise stay locked in place.)
Another good practice – also employed in Woorld – is to have visual elements showing if your app is scanning for something.
When designing VR/AR content, one technique Cassin finds helps is to design within VR/AR itself such as with Tilt Brush. This gives a better perspective on how your vision will translate into virtual reality. “The faster you get into VR, the better. That way you can conceptualise it, you know what’s going on, and you’ll know how to approach it.”