Presence, Reality, and the Art of Astonishment in Arizona Sunshine

Published: 12/01/2016  

Last Updated: 12/01/2016

On Presence

In a habit I picked up from one of my Engineering heroes, Rich Hickey, I’d like to start with a definition.

(Aside: Rich Hickey is the designer of the programming language Clojure and did an amazing talk, available on InfoQ, called Simple Made Easy. You should watch it)


The state or fact of existing, occurring, or being present in a place or thing.

Dr. Matthew Lombard, in his paper “Research on Presence in Virtual Reality: A Survey” defines presence thus:

A psychological state of subjective perception in which even though part or all of an individual’s current experience is generated by and/or filtered through human-made technology, part or all of the individual’s perception fails to accurately acknowledge the role of the technology in the experience.

Take a look at those definitions, the first is the literal definition of the word ‘presence’ while the second talks about the experience of presence itself. Both describe the concept of existing, believably, in a place; of persuading a persons perception that the world they are now perceiving is the world in which they are actually now ‘present’.

To me, that sounds a lot like the goals of VR; create a virtual world that someone can believably exist in, and persuade their senses that they are actually present in that world…and it looks like the, growing, VR industry agrees with me.

Brendan Iribe, CEO of Oculus, dedicated keynote time to the concept of presence at Oculus Connect back in 2014. In that keynote he identified five key technical requirements needed to produce presence, these were:

  1. 6 Degrees of Freedom (6DOF), sub-mm accurate, tracking
  2. Sub-20ms Motion to Photon (M2P)
  3. 90 frames per second (FPS) rendering
  4. Sub-3ms latency displays with minimum 1Kx1K pixels per eye
  5. Wide Field Of View (FOV), well calibrated, well corrected optics

Since that keynote we’ve met, and in some cases exceeded, these technical requirements; even now though some VR experiences fail to deliver the, often elusive, sense of presence. So what have we missed, what have we been over looking in these discussions?

We, as an industry, have been so focused on the visuals, on fooling the eyes, that we forgot that those eyes have a user attached to them. We forgot that the user has a mental model of the world that goes much deeper than vision, that the user has a powerful computer between his ears, a computer that has expectations of how the world works.

I contend that once you’ve met that minimum bar of technical requirements the biggest indicator of presence is not graphical fidelity, or ‘realistic’ visuals, but consistency with the users expectations, consistency with that internal model of the world.

Reality and Astonishment

The Principle of Least Astonishment, also known as the Law of Least Surprise, states:

If a necessary feature has a high astonishment factor, it may be necessary to redesign the feature

In general, the principle can be taken to mean that a component of a system should behave in a manner consistent with how users of that component are likely to expect it to behave; that is, a user should not be “astonished” at the way it behaves.

To put it another way, people are part of the system, anything you design should meet the users experience and expectations, and build upon their pre-existing knowledge.

Note, the principle does not say somethings behavior must be in a manner consistent with reality but in a manner consistent with how a user expects that thing to behave, with the users mental model of the world; a mental model that we know has pretty significant differences from reality (why do you think you always forget what you went into the kitchen for?)

So, what does that mean in the context of VR?

Consider a hypothetical room. In that room is a table, on that table is a coffee cup, and a pile of tennis balls (yes, it really is a weird room, and no, I doubt anyone would actually build this…bare me with, please).

The Principle of Least Astonishment means that I should be able to pick up that cup of coffee, that it should have coffee in it, that the coffee should be steaming, that I should be able to pour it out onto the floor, that the coffee stays on the floor till it drys up, or the user forgets about it (remember, user expectation rules here not reality). It also means I should be able to pick up a tennis ball, roll it around, throw it at a wall and it should bounce (and bounce like a tennis ball, not a ping pong ball, or a marble). I should be able knock over the stack of balls, I should be able knock over the table, I shouldn’t be able to walk through the walls. The walls should have texture, the windows should have a world outside, that world should change and move, people pass by, trees sway in the breeze, birds fly in the sky…and all of these things should sound ‘right’, even as I move and rotate my head (something for which standard stereo sound is insufficient).

I won’t belabor the point further other than to say that early research seems to agree with me. The conclusion of “Presence: Interacting in VR?” [Martijn J. Schuemie, Charles A.P.G. van der Mast, Delft university of Technology, The Netherlands] states “this article clearly determines interactivity of virtual environments as an important cause of presence”. Obviously it’s still too early to claim this as an absolute fact, but anecdotally it seems to hold up.

So…what does this mean for Arizona Sunshine? I’ve talked a lot about theory, but I’ve still not actually talked about the game that’s right up here in the article title.

Arizona Sunshine

Firstly, before I go any further I would like to thank Vertigo Games for working with us on Arizona Sunshine, it’s a very fun game that we’ve used at several different events, always to fanfare from those that try it. Check it out on their site.

Arizona Sunshine

With that said, I should point out that Arizona Sunshine does a number of these things very well out of the box. Consider the tennis balls analogy above. That is actually straight out of a demo from the Intel VRDC booth. The first thing one of the users did was see a pile of tennis balls, walk over, pick them up, and start throwing them at zombies…and it just worked, the zombies even reacted. Great work Vertigo Games.

So what did we add?

Environment Destruction & Carnage

The most obvious stuff comes in the form of environmental destruction and carnage:

  • Throw a grenade, it explodes, the crate next to it get’s blown into shards and the floor is cratered from the force.
  • Shoot a sign and it moves, shoot it enough and the wood splits, the sign breaks.
  • Shoot a cactus and it moves, shoot it enough in just the right place and it breaks, pieces of it fall to the floor.
  • Shoot a zombie in the arms and you can blow them clean off

…or my personal favorites:

  • Want the resources in the car? Don’t open the door, just break the window and take them.
  • Want to shoot the zombie in the building? Don’t go in it, shoot them through the window.

Weather Effects

This one is pretty simple, the game has wind effects now. Plants and cloth sway appropriately in the dynamic breeze.

Background Details

Finally, we worked with Vertigo to add richness to the background. You’ll see carrion birds flying overhead, all with flocking behavior, and you’ll see hordes of zombies in the background.

Do any of these effects change the core game? No, but they make for a richer experience, an experience that is more inline with a users expectations, an experience that has more presence.

Can I Run It?

Short answer, if you meet the old Oculus min. spec (Intel Core i5-4590): yes…but you won’t get these presence improving effects. For those, you’ll need a high-end Intel Core i7. Just ask Tom’s Hardware.

The truth is, VR is a much more demanding workload that classic monitor driven gaming for both the CPU and the GPU. The move to 90FPS, low M2P, and 2160x1200 pixels per eye, dramatically increases the total compute requirements. In many cases, and increasingly, the GPU is so swamped keeping up with rendering that physics is being moved off onto the CPU. The CPU becomes responsible for this additional work, while still needing to run the complete game simulation, all in 50% less time. Even todays high-powered Intel Core i5’s can’t maintain 90FPS with all of these extra features turned on.

The exact technical reasons for this are many fold and complex, and I’d like to leave answering those to both Vertigo Games and the Intel engineers that worked with them. Check out the video below for the whys and hows of i5 vs i7 in Arizona Sunshine.

And with that all said and done, I’d like to sign off. See you next time.

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