Standing ground of VR today

Author : Olivier Lapointe

Date of writing: 2016 – 08 – 20

Standing ground of VR today – Olivier Lapointe – 2016/08

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Content Abstract ......................................................................................................................................................................... 3

Introduction .................................................................................................................................................................. 3

Computing Requirements for VR .................................................................................................................................. 4

GPU’s up-to-date ....................................................................................................................................................... 4

Head Mounted Displays up-to-date .......................................................................................................................... 5

The requirements of tomorrow ................................................................................................................................ 6

Games for VR ................................................................................................................................................................ 7

The many Other VR devices .......................................................................................................................................... 9

Head Mounted Displays ............................................................................................................................................ 9

Controllers ............................................................................................................................................................ 10

Eyetracking .............................................................................................................................................................. 10

Body Mocap ............................................................................................................................................................ 11

Base platforms ........................................................................................................................................................ 11

Glove haptics ........................................................................................................................................................... 11

Body Haptic .......................................................................................................................................................... 11

Brain ....................................................................................................................................................................... 11

Speech ..................................................................................................................................................................... 12

VR Motion Sickness [, , , ] ........................................................................................................................................... 12

Experimenting game locomotion controls for VR ....................................................................................................... 14

UE4 VR Playground [, ] ............................................................................................................................................ 14

Two examples of ThirdPerson VR games ................................................................................................................ 17

Conclusion ................................................................................................................................................................... 17

References .................................................................................................................................................................. 18

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Abstract Virtual Reality is still very young. However, its coming, its here to stay, and it has very high

demands. Overall this paper is video game development oriented and gives a heads up

on what VR is, its limits, problems, costs and avenir. Its main focus is on the Head Mounted

Displays such as the oculus rift and the HTCVive. It also proposes a section introducing

many other VR devices. It goes further into details explaining what motion sickness is, what

causes it and how it can be addressed in video games. It offers a few methods of

locomotion used to fight motion sickness. It gives a summary and an analysis of the games

released in VR and the ones coming in the future. Lastly, it also approaches the

computing and hardware cost of developping for VR and its expectancy of progress for

the future.

Introduction This paper talks about the constraints and requirements of Virtual Reality provided by

Head Mounted Displays in video games. VR is coming and aims to bring current

generation gaming up to amazing new heights. However, on the content development

side, this level-up is nowhere as simple to just duplicating the viewport and rendering

these with a slight shift on the yaw. Developping for VR is much more ressource expensive

than for traditional monitor gaming. This paper will begin by dwelving into the cost of VR

to give an idea of what to expect on the hardware side. Next it will introduce many of the

released and upcoming games for VR and provide an analysis of what they are, what

makes them special, as well as what is missing. Althought the main focus of this paper are

HMDs, it also introduces some of the other VR devices and how they could boost the

overall immersion. After that it‟ll dig into the motion sickness problems of VR and what can

be done to mitigate or nullify these adverse effects. Lastly it‟ll expand a bit more on the

subject of motion sickness and present a few methods of locomotion to be adopted and

adapted in VR experiences.

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Computing Requirements for VR This section talks about the cost of developing for VR; where GPU‟s and screens stand

today and where they need to be going. To do so I will mention facts as well as attempt

to make simple calculations to give a middle ground where to land our expectations.

Let‟s start this section by taking a big punch by looking at the raw amount of pixels we

need to render for VR with this slide from Alex Vlachos‟s speech on Advanced VR

Rendering at GDC2015.

Alex Vlachos‟s, Advanced VR Rendering, GDC2015 i

Doing some simple math we can deduce that VR requires 3 to 4 times more rendering

power than current monitor gaming, at the current HMD resolution. Though eye tracking

and FOV rendering will be coming later on, this is still a big jump. Even more when we take

into consideration that this resolution is nowhere near what we would want to render.

GPU’s up-to-date

Let‟s take quick look at where GPUs stand in the consumer market today and how well

they‟re performing. Current generation GPUs like the NVidia‟s Gtx 980 perform perfectly

with today game demands, 1080p @ 60fps, everything maxed out. The PS4 and XBoxOne

come equipped with an equivalent GPU processing power to NVidia‟s 750ti ii, which has

1/4 the performance of the 980, and still seems to perform pretty well at 1080p @ 60fps.

The following chart displays the increase of performance Nvidias has made with its GPUs

by comparing the latest Titan X Pascal with the top cards from their previous series.

Name 580 680 Titan Z 980 Titan X 1080 TitanX P

Release

Date

11-2010 03-2012 03-2014 07-2014 03-2015 05-2016 08-2016

Perf % to

the TXP

370% 250% 160% 100% 55% 20% 0%

Release dates from Wikipedia, and performance gains calculated with gpu.userbenchmark.com

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Taking into account these simple numbers, we can observe GPUs almost double in

performance every 2 years and that we‟d have to wait 4 more years for the „Gtx Titan X

Pascal 2‟ before moving into „serious‟ VR game development. However, these are just

simple and raw numbers to be taken into consideration rather than a live by rule as there

are many more factors to take into account. First of all comparing GPUs isn‟t this simple,

as numbers can mean something on paper and something totally different in-game as

new technologies emerge. New technologies such as DX12, which don't change the

GPUs themselves, but how they process information. Secondly, and above all, it really

boils down to the type of game. A first person hyper-realist multiplayer fast paced game

will perform totally differently when compared to low-poly single player wall ping pong

game. Lastly we can just look at 2 already released incredible, beautifull and realistic

games; Adr1ft and EVE Valkyrie, and witness their excellent performance on the Gtx980.

In the end, all this means is that VR has higher performance demands than traditional

gaming, but great games can already be accomplished.

Head Mounted Displays up-to-date

On the HMD hardware side, the most important factors are the refresh rate, the

PixelsPerInch (ppi) and the quality of the screen. The minimal refresh rate on monitors and

TVs is 25fps, below this number our eyes can make up the jump between frames. However

in VR the screen display is right before our eyes and covers much more of our field of

view, this raises the minimal fps to 75. Anything below will break the immersion and even

make the user feel sick. Good news is; all current headsets already have a refresh rate

between 90 and 120fps.

Bad news is, since the display is up closer, the pixels on screen appear bigger as the PPI

isn‟t enough. In game this translates to blurry objects, big broken edges and unreadable

texts. The Oculus Rift DK2 has a PPI of 386, its commercial version (CV1) and the HTC vive

have 455ppi. The PSVR will have 386ppi as well. These values are great, but they are

nowhere near minimal comfort zone.

From my own experience with the Rift DK2, I‟d say that a PPI 3 times more significant

(1200ppi) might be enough to make each individual pixel not easily distinguishable.

Though for the ideal experience we might need to reach 8K displays, which is 8 times the

current 1200x1080 resolution per eye in those headsets. If my linear and optimist math is

correct, this would lead to 3000ppi displays. This is pretty ambitious on the hardware and

the processing power required to render such large frames.

All isn‟t without hopes though, at least on the hardware aspect, as current market

available smartphones are already capable of 806ppi. Generally smartphones have a ppi

of 350, the GalaxyS6 reaches 577ppi and it is the Sony Xperia Z5 Premium that owns the

highground with 806ppi LCD. However, smartphones screens tend to be LCDs whereas all

VR HMDs require OLED screens. Different technologies mean different progress

breakthroughs. The Sony Xperia Z5 came out in November 2015, now, almost a year later,

Samsung prepares to release the Galaxy S8 with a 806ppi AMOLED screen. With this said,

it is important to remember that with VR mounts, such as the Samsung GearVR, it is

possible to use a smartphone‟s screen for VR.

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The requirements of tomorrow

So the future of HMD hardware is promising here too, but what about the GPUs? If we

can‟t render such HD images, of what use are these HD displays? Though it may not fill the

whole gap, the aforementioned Field Of View rendering might help by reducing the load

we send to the GPU. With eye tracking we can know exactly where the user is looking at.

With this information we can decide what part of a scene to render in high quality while

setting all the rest to a lower one. This means that we wouldn‟t be rendering the entire

screen at 100% but only ~20% of it and cap all the remaining 80% of the screen between

60% and 20% quality. There is no quality loss of image from the user‟s perspective, but

there is no telling yet either how much work it would spare on our GPU.

Foveated Rendering, SMIvision talk iii

Considering all this new information on the ideal resolution we would dream the HDMs to

have, lets kick in some simple linear math to calculate how many Gtx Titan X Pascals we

would need for modern games to render in 16K, everything maxed out. By taking the

performance information of the Gtx TXP from eurogameriv and applying linear math we

come up with 32 Gtx TXPs. Without FOV rendering and DX12/Vulkan.

Linear Optimist Math:

-Let‟s take Far Cry Primal as the middle ground.

-At 1080p the Gtx TXP can render 260Million pixels per second (132fps * (1920*1080)).

-At 1440p it does 350M pixels per second (96fps * (2560*1440)).

-At 2160p 400M pixels per second. (50fps * (3830 * 2160)).

-To render at 16K we need to render 11 500 M pixels per second. (90fps * (16K*8K)).

-Taking the middle ground in Million pixels/second, we would need 32 Gtx TXPs.

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Performance of the Gtx Titan X Pascal on various games, eurogamer.

Scary, right? However, if we consider that GPUs performance doubles every 2 years as it

did with the recent 980 and 1080, it might just take 10 years before reaching that point in

performance. We have to keep in mind that these stats are for intense ressource

demanding games and that many other great games don't need that much. Lets

remember that the workload might as well be cut in half with FOV rendering. In the end,

8K is an ideal resolution, 8K and 4K would already greaten the experience by a lot. Also,

we have to keep in mind that there are many other parameters to take into account.

What this information and non-relevant math do here is provide us an idea of where were

standing today, where we need to go and what to expect in the future. The other thing is,

we do not need to wait for all this gear to come before having great and awesome VR

games as.. there already are many of them out there !

Games for VR While waiting for better GPUs and screens to release, let‟s take a look at the awesome VR

games that are already here. I have compiled a list of games representing their genre.

Right after I will present a short analysis of what is out and what is missing. Most of these

games have already been released and only a few of them are to come end of 2016, or

2017 with the release of PlayStationVR. They can be found on Steam and the Oculus

Home store platforms. Other great free games and experiences can be found on WearVr

and itch.io.

Dragon front : tower defense game with top-down and „turret‟ view.

Battlezone : battle tanks in arenas with first person cockpit view

Adr1ft: space station exploration in 1st person with emphasis on realism and the loneliness

of space.

Rigs: cockpit view, giant robots battle in arenas. Fast and agile gameplay.

EVE valkyrie: Mutiplayer space ship dogfighting in first person.

Gran turismo sport: car racing,

Classroom aquatic: exam cheating simulator in a dolphin school by making disctractions.

Eagle flight : bird flight simulator in Paris with friends.

Robinson the journey : 1st person exploration adventure in dino-land.

The climb : 1st person rock climbing and sight gazing.

Rock band vr : rockband in vr.

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Gunjack: 1st person space turret defense against waves of ships.

Surgeon simulator : aliens surgery in 0 gravity, now more precise than ever.

Job simulator : mess around with office and kitchen objects.

Time Machine : Pod under-water and sky exploration with time traveling to record

different prehistoric species.

Vr Karts: Kart racing in vr.

Minecraft VR : minecraft in vr.

Resident evil 7 : horror shooter.

Paranormal Activity: horror/suspense game.

Farpoint : 1st person alien planet exploration /survival

Fallout 4 VR : game adaptation for VR.

CCP's Project Arena: tron like disk arena.

Serious Sam VR: 1st person frenetic shooter with beheaded kamikazes.

Star Trek Bridge: coop space simulator & ship management.

Chronos : 3rd person fixed cameras adventure .

Tekken 7 : fighting in 3rd person fixed camera.

Windlands : 1st person grappling hook exploration on floating islands and ruins.

Radial G : 1st person tube racer.

Subnautica: alien planet underwater exploration and survival.

Farlands : Planet exploration and discovery of alien life forms and behaviors.

Technolust : immersive 1st person cyberpunk adventure novel where you unravel mysteries

of a new world.

Budget Cut: Indoor exploration and puzzle solving with blink movement system.

Audio shield: space/tron like 1st person ping pong rhythm.

Brookhaven experiment: zombie onspot shooting.

Holopoint: vr archery with the Vive‟s wands.

Fantastic contraptions: build crazy awesome vehicle & make it roll

Hover Junkers: Roomscale ships multiplayer fighting and shooting.

Selfie Tennis: Solo tennis in „unicorn land‟.

From all this we can notice a lot of games where you are seated in a cockpit and move

with it. The main reason behind this is because it greatly reduces motion sickness.

Nevertheless, the experience is pleasant and the gameplay works very well. This is the best

way to start experiencing VR games. Some of them are: Time Machine, Hover Junkers,

EVE Valkyrie and Gran turismo, just to name a few of the vast majority.

Next, there are many „turret‟ games where you stay on spot and do stuff but do not

change location by an inch with the controllers. This is also because of motion sickness, if

there is no cabin to fool the mind while moving, then user will probably get sick. Therefore:

no movement. Some of them are: Fantastic Contraptions, Gunjack, Brookhaven

Experiment Surgeon Simulator and Job Simulator.

Some games do overcome this limit a little bit by allowing the player teleport itself

somewhere else instantly. This method is 100% motion sickness proof and works wonders.

However, it isn‟t very immersive. Some of them are: Budget Cuts, Farlands and Bullet Train.

Other games allow you to move freely on ground and rotate the camera as much as you

want. They can heavily induce motion sickness to non-experienced players but are a

breath of fresh air in freedom of movement for those it doesn‟t affect. Some of them are:

Technolust, Adr1ft, Robinson the Journey and POLLEN.

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More heavy games break the ground and allow the player to swing tree to tree or move

freely in the 3 directions. They would be expected to induce instant motion sickness.

However, in the case of Windlands I‟ve only heard great opinions. And having personally

played Subnautica for more than 15hours, I can give an insight of my experience. The first

3-4 hours were harsh when rotating the camera with the stick. However, after the 8h mark

I‟d only feel a minor discomfort probably due to the poor optimization of the game for VR,

and the low resolution of the DK2. By now I can dive in for 3h straight before having to

surface again, not because of feeling bad, but because of my way of playing. Of course,

adaptability is different for everyone.

Overall, all of these games are in first person view. Third person games and top-down

games such as Darksouls, Starcraft2 or Diablo3 are nowhere to be found. There aren‟t any

frenetic first person shooters like Titanfall or COD either. There is however a „Super Mario 3D

world WiiU‟ (3rd person platformer) like called Lucky‟s Tale. No 3d or 2d Turn Based Game.

There is a flappy bird like 2d demo sidescroller called Bubble Inferno, but no real 2d

games. Tabletop games such as chess and Hearthstone are on their wayv. We may also

soon be expecting bowling, pool, mini-golf and wack-a-mole type of arcade games

where you can interact with your hands like you would outside of VR.

As of today, still many common games types are missing in VR. This is not surprising

however, as VR still faces many problems; starting with motion sickness, the resource cost

is also higher, there aren‟t enough devices out there for companies to want to support or

make such games, some genres would have no or almost no benefit of going VR, the

freedom of camera could break the rules for some, others would suffer from the display

resolutions, but above all, VR is still very young. Some of these games will come very soon,

others will take their time, and the rest will come much later on when HMDs will be

capable of truly replacing our monitors and TVs.

The many Other VR devices When talking about VR we mostly think about the Oculus Rift, HTC Vive, google card

board and other Head Mounted Displays as they utilize our most important sense; vision.

Rarely do we ever think about all the other ways we have of interacting with the world.

This section will do just that; introduce the many other devices that along the HMDs will

greatly increase the sense of immersion in VR. As I won‟t go too much into particular

details, I‟ll often join links that lead to more information on how they work.

Head Mounted Displays : The Occulus Rift and HTCVive are the most known HMDs, but

there also are a few others to keep track of. The Razer OSVR HDK2 packs similar hardware

specifications and defines itself as the open source VR Headset. On the living room

console side, Sony has the PSVR headset, aka Morpheus, coming up soon.

With the immersion HDMs provide, we also want to have more immersive means of

interacting with the world around us. We‟ll no longer want to simply press the „E‟ key to

interact or pickup objects, we will want to do so physically or mentally and have physical

feedback of us doing it. This sections aims to introduce other upcoming technologies that

if don't become absolutely necessary with HMDs, will greatly enhance their experience.

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Controllers

Having new ways of seeing and interpreting the universe around us, opens up the

possibility of new ways of interacting with it.

Sixsense Stem Controller : This controller takes your traditional wireless dual stick controller,

splits in half for each hand and adds 5 point positional trackers for your hands, feet and

head. This allows the user to perform basic leg and arm movement with their body and

see it reflected in-game. It works well enough for the user to see himself walking, jumping,

spinning and sword fighting. This controller having only 5 positional trackers relies heavily

on inverse kinematics to tell how each arm or leg is positioned and bended.

Full body test: https://www.youtube.com/watch?v=jkOLswJlTBs

TacticalHaptics‟s ReactiveGrip : They basically took a typical stick controller and added

force feedback so the user may feel weight, gun recoils, sword cling, and other weapon

or hand wearable physical properties. On the demo it was used as an add-on to Stem‟s

predecessor, the Razer Hydra.

Myo Armband : This armlet detects muscular activity on the arm and hand it is worn on. It

can only recognize up to 5 gestures (wave left, wave right, spread fingers, fist, and thumb-

to-pinky). Its application is somewhat limited to the patterns it can detect, how well it can

recognize them without triggering false positives and the use we can come up with. For

now Myo has already proved itself in its usability for presentations, video and music

players (think of next, previous and pause functionalities). However it also sees its

appliance in video-games. On their website, Myo provides support for many games such

as FruitNinja, Civilization5, NFS MostWanted, Minecraft and Skyrim, just to name a few, but

actual gameplay is yet to be seen.

In life Myo applications: https://www.youtube.com/watch?v=te1RBQQlHz4

LeapMotion : This little black box offers neat dual hand and fingers gesture recognition via

a camera. Yet, it is somewhat sensible and does not support hand over hand interactions.

It work really well as a mean to interact with your screens. Basically, what it does is add

touchscreen functionality to any screen (monitors, TVs, projectors). On the gaming side,

seeing and using your hands in-game is a huge plus and there already are many mini

games of the leapmotion website as well as experimental games on itch.io to try out.

Test LeapMotion: https://www.youtube.com/watch?v=bvkyEUb2NnA

Eyetracking

Eyetracking in VR enhances the experience by a lot; the ability of knowing where the user

is looking at the screen removes the need for tiring neck-movement and mouse usage. Its

main functionality is to facilitate interactions, but with FOV rendering it might also reduce

GPU workloads.

Fove : Is the first Head Mounted Display to feature integrated eye tracking. On the specs

side it has similar features to the Rift and HTCVive.

Eye Tribe Tracker : The Eye Tribe have come up with a stand-alone eye tracking device

that can work with any TV or integrated into other HMDs.

Tech Demo EyeTribe: https://www.youtube.com/watch?v=NZaQEQrk15A

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Body Mocap

Sixsenses‟s Stem provides basic body tracking, however PerceptionNeuron and PrioVR

take the next step by increasing the number of sensors from 5 to 12 minimum and up to

32. With that many trackers on the body, pose recognition becomes very easy and

reliable enough to even be used in mocap animations.

Perception Neuron test: https://www.youtube.com/watch?v=cvqL2LQjBgQ

Base platforms

One of the main limitations with VR is the limited space you‟re playing in, which restricts

your body movements to basically standing, hoping to not unconsciously bump into a

wall or a lego.

Cyberith‟s Virtualizer and KatVR‟s movement platform allow the user to walk, run, crouch

and jump endlessly on one spot, without moving by a single inch.

GTA5 gameplay with the Virtualizer and Rift:

https://www.youtube.com/watch?v=6CZmJvI8mfc

Glove haptics

Gloveone and Dexmo have basically made mocap for hands. Their gloves allow tracking

and recognition much like the LeapMotion does, however it is much more accurate and

does not have the problem of one hand blocking the another. Their devices have

somewhat different bonus capacities. Such as haptic feedback that allows the user to

feel the rain, guitar cords and butterfly wings amongst others. As well as force feedback

to simulate your hand holding something, for example offering resistance when trying to

fully close your fist while holding a fishing pole.

Kickstarter Gloveone: https://www.youtube.com/watch?v=RAZidk_mPc8

Dexmo demo: https://www.youtube.com/watch?v=MBBQrGug_Go

Body Haptic

TeslaStudios came up with the TeslaSuit, a suit that covers your body and simulates

different feelings such as heat, cold, touch and impacts.

Trailer TeslaSuit: https://www.youtube.com/watch?v=RMBwb8megGE

Brain

Emotiv‟s Epoc+ is a Brain – Computer headset interface that allows the recovery of data

from brain activity… as well as facial. With it you can move a box in VR 3d space just by

using your thoughts. The immediate down side is that it requires a very high amount of

concentration for it to work and is therefore slow and sluggish to react. This however did

not stop some people from using it to move real life miniature mechanical robots.

Developpers from the game Son of Nor also use it to swap and cast spells. Also to note, 4

years after the release of the device, there aren‟t many applications or usages being

announced or teased. However this could and would be a very great addition, and

definitely the future of how we want to interact in VR

Mind controlled robot : https://youtu.be/nX741DZw8l4?t=5m7s

Son of Nor epoc introduction: https://www.youtube.com/watch?v=U0ML3YWn34w

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Speech

Pronouncing words to perform actions is the step right before mind control. Tie actions to

words and have them triggered without having to use a physical gamepad button can

be faster, feel more immersive and allow this button to be mapped to a more important

command. Because in VR we‟ll have much more things to interact with and do, and we‟ll

want them to feel as real as what we see.

Elite Dangerous Astra (space sim): https://www.youtube.com/watch?v=DRVCkUN_Mq8

In Verbis Vertus (spell casting): https://www.youtube.com/watch?v=oBRiuAaBhNI

Head Mounted Displays act as catalysts for all these other devices. They are already

great by themselves, but they will only reach their full potential when paired with HMDs,

and vice-versa. Some of them are still in the early stages and the arrival of VR to the

consumer‟s market will greatly increase and speed their development.

VR Motion Sickness [vi, vii, viii, ix]

Virtual reality motion sickness is the biggest frontline issue VR faces with new users and

media covering. It can be caused by many things and affects everyone on different

levels of intensity. It basically boils down to you feeling sick while wearing a HMD. The

symptoms can include: general discomfort, headache, stomach awareness, nausea,

vomiting, pallor, sweating, fatigue, drowsiness, disorientation, and apathy. These will

dissipate relatively fast after exiting VR and the person will get back to normal. Though the

main cause for this is due to a difference between what you‟re seeing and what your

brain expects to see, there many other factors to consider:

Mistmatched motion: This is due to a discrepancy between how we are moving in VR

and how our brain expects us to do so. For example when walking down cliff, walking up

stairs or simply having the ground pulled from under our feet. Our brain expects to feel

something, and to not feel anything makes him think we‟re sick. Movement speed can

also apply here, as our brains aren‟t used to our body moving around 20mts/s. Jumping

high in the sky and landing without crouching can also feel weird. When we move in real

word our body receives tons of information besides the eyesight, in VR only our eyes

receive information of movement. It is this lack of other information that make us feel

weird. Lastly, it is important to know that this affects everyone at different levels and that

some people don't feel any discomfort whatsoever.

Motion parallax: As we move in the world we expect things close to us to move faster

than those far away, a mismatch in this information will cause discomfort. Our brain has its

own way of interpreting depth and distances. Tricking him into making farther objects get

near to us faster than close ones is something he isn‟t used to. In other words; don't make

the mountain approach faster than the penny.

Field of view: While having a very high, or low, FOV on our monitors does not affect us in

any way. With VR, it is important to respect the one established by the HMD. Because the

HMD is very close to our eyes, fills most of our view and promotes a sense of immersion, our

brain expects to see stuff exactly like it would outside of VR.

Mismatched reality: This comes in when what we see feels real enough to be real but

isn‟t. For example when having a mesh represent your hands in VR that looks real but fails

at having the right scale, finger lengths, position or rotation offsets match yours. The same

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can be said with realistic animations and facial expressions that aren‟t 100% accurate.

They look good, but the little thing that misses makes it feel uncomfortable. In these cases

it is better to fake all along and cancel any expectations our brain could have. This can

also apply to the height of the camera in-game, as a 2.10mt tall person is used to see

things differently than a 1.50mt one.

Level of detail : This is very much related to mismatched reality in the sense that we

expect things to look how they should, but this time it is due to how developers create

these things rather than the feeling itself. The big word here is Normal Maps. Normal maps

act as images that fool our perception of volume by playing with the way edges and

details are lit when we can‟t afford to put real geometry. For instance, on a wooden door

we often trick the wood details with normal maps instead of using vertices. This works

great as long as the camera remains far enough. However the illusion breaks when it gets

to close. On monitors this would only look „cheap‟, but in VR it‟ll make us feel awkward as

we see depth but don't see really see it.

Color: Some games have increased contrasts in colors and intense lighting effects. In VR

this could increase simulation sickness. It is therefore recommenced to keep normal

contrasts that don't „burn‟ our eyes as well as not using too many bright-white tones that

would blind us outside of VR as well.

Camera Effects : It‟s strongly recommended to not use Head Bobbing, Depth of Field nor

Motion Blur as all these effects come override our natural way of seeing things.

Forced orientation: Force rotating the camera to look somewhere or allowing the

player to do so with the right stick, will cause motion sickness. This is due to a conflict

between what the eyes see and what the vestibular systems expects to feel.

There are many ways of impeding this problem:

1. Not allowing it, simply lock the orientation to the HMD.

2. Instant rotation.

3. Clipping the rotation; rotate of N degrees instantly.

4. Reducing the FOV while turning.

However this isn‟t always a problem as some people don't feel uncomfortable while doing

it and others grow immune to it. Thought, forcing camera rotation without the user‟s

consent, will always feel awful. If developers want the player to look somewhere, they

must motivate him to do so.

Acceleration: Also caused by a conflict with the vestibular system, acceleration will

cause motion sickness. However, this is reduced (and even nulled) if the speed is

constant. The direction in which we move (forward, backward, left/right strafing) also

influences differently. We are most confortable at linear speed going forward and user

controlled.

Time: Motion sickness comes progressively and the longer the user stays in VR, the more

intense the symptoms will become. Conversely, motion sickness will mitigate over time the

more the user spends time in VR and gets used to it.

Refresh rate: While a refresh rate of 25 images per second might suffice on monitors and

TVs to trick our brain into believing he‟s seeing a continuous action, VR requires at least 75-

90 frames per second. The framerate must also be stable and not oscillate too frequently.

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Lag: Actions performed in VR must immediately be reflected in front of our eyes. If there is

a split second between the moment we turn our head and the moment we show the

right image, we will feel sick.

Life: Finally, anything that would make someone sick in real life will most likely make her

sick in VR as well. Someone who feels vertigo, claustrophobia and/or other phobias

outside of VR, will feel the same in VR.

Experimenting game locomotion controls for VR Having read and researched about different ways of dealing with locomotion and

motion sickness in VR, there are some I got to try and others I didnt. In order to try these

other methods I made a small project with Unreal4. What I did in this playground is

implement some of these methods and design a level in which to test them. For

disclaimers, because of time constraints, I havent implemented all of the methods I‟ve

read about nor made a test level that fully exploit their characteristics. The reason for this

is because a method might very well work on a small test such as this, but will probably

feel totally different when confronted to real gameplay. The end purpose of this

playground is to simply try these locomotion methods to get a general feeling of how they

could work in-game.

UE4 VR Playground [x, xi]

In this little project I did two things: implement 7 methods of locomotion and design a level

in which to test them. The methods are split in first & third person cameras. All methods

share similar input controls but differ at their particularties, which often is how to deal with

rotating the camera. The input method can be changed on the fly by using the 1-7 keys

or the select button on an Xbox controller. At every change, a board is displayed to

inform the user of the changes in input.

In game board informing the inputs of the selected controller.

As follows, I‟ll introduce the different methods implemented and what makes them work.

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1 Clip Angle: Freely rotating the camera with the right stick is extremely nauseating and

probably the biggest problem when trying to have the freedom of monitor controls in VR.

However, instantly rotating the camera of N degrees at a time does not trigger motion

sickness. In this example the user can rotate the camera of 90 or 22.5 degrees at a time

by using the shoulder and trigger buttons. Although this method feels great in terms of

comfort, it doesn‟t feel as immersive and locks a lot of buttons. Even though we can

rotate our body in real life and see it happened in-game, relying on buttons is much

easier as physically performing the action every time can result tiring.

2 Tunneling: Depending of the user, sometimes the simple fact of moving forward can

feel nauseating. The solution for this is to instantly transport the user where he wants to be.

There are 2 ways of doing so; blinking and tunneling. Blinking instantly transports the player

to the targeted area, whereas tunneling does so progressively providing a sense of

motion. The tunneling is done quickly enough so that the player notices being displaced

but doesn‟t have the time to feel it. For very motion-sickness proof controls we could well

enough combine Tunneling with Clip Angle.

3 Clip Orient: This method is somewhere in between Clip Angle and free rotation. With

the right stick we get to tell our body in which direction to orient itself. We pull the stick in a

direction and on release our body faces this direction. For example; when we pull the

stick backwards, the camera rotates 180 to face backwards. If we repeat this action,

we‟ll be facing our previous „ahead‟.

The action of tilting and releasing the stick to instantly change our orientation does not

trigger motion sickness, feels a bit more immersive than Clip Angle and also is much

quicker to perform. However, it is quite sensible and demands some practice before

being capable of pulling the perfect angle.

4, 5, 6 Third Person : Very much to my surprise, I couldn‟t find any game offering 3rd

person view controls. Therefore this part relies entirely on my experiences, which ended up

begin very comfortable and immersive. The most nauseating experience in first person is

to turn the camera with the stick. However, in 3rd person the effect is greatly mitigated

and almost feels natural. At least on the Z axis, as on the others it blows your eyes as much

as in first person.

In 3rd person the camera can rotate relatively to two coordinates: itself or the character.

In my experience they both feel very good, but I have a slight preference with the

camera rotating around the character as it made me feel more connected.

In regard to walls and the camera pulling itself closer to the character, I did not feel any

discomfort.

7 Caged Rotate: The main difference between 1st and 3rd person cameras is that in 3rd

you have the character to look at all the time. Pulling your focus onto something constant

reduces the discomfort while turning the camera. In Eagle Flight Ubisoft reduces the Field

of View by obscuring the edge of the eyes whenever the user uses the stick to turnxii. This

simulates a “TV” effect and reduces motion sicknessxiii.

Althought I did not finish implementing this method, what I did do is lock stick rotation

whenever the user was turning his head in the opposite direction. So if your head is

rotating left, you can only use the stick to pivot left as well. If your head isnt moving too

much, then you may use the stick in any direction. In VR it is something to rotate the view

without having your head do the same thing. However it is something completely

different and worse having your head turn one way while pulling the stick the another.

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For the playground, if we recap, with VR, the locomotion the actions that are most likely

to induce motion sickness are: walking, turning (on yourself or around a target), climbing

straight or spiral stairs, jumping, falling and feel vertigo. I designed the playground to be

open world with lots of vertigo inducing places.

I‟ve uploaded a test video of this project on youtube, as well as the build for anyone to

try, on this address: https://www.youtube.com/watch?v=40lG9ZxhKd8

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Two examples of ThirdPerson VR games

To conclude this paper, I wish to give a little better idea of what third person gameplay

could be in VR. I‟ve uploaded two gameplay videos of some projects of mine.

The first, don't let me Die & Retry, is a project I made with friends for school during my M1

at l‟ENJMIN. It is indoors, goal oriented and atmospheric.

https://www.youtube.com/watch?v=lgb7aOSV9bw

The second is sort of my UE4 playground that I simply partially ported to VR. It‟s outdoors,

open world and adventure oriented.

https://www.youtube.com/watch?v=mbXq7agbrpM

Conclusion As of today VR still has many challenges to address, both on user comfort and hardware

requirements. Thought the hardware is not yet at its ideal stage, great experiences have

already been created, many more are on the way and we can rest assured that it‟s only

a matter of short time before it reaches perfection. Motion sickness and what it means for

traditional locomotion in games already has developers searching and finding different

solutions. These alternate methods are split between comfort and immersion. At the

moment it mostly falls back on the developers to solve these problems in their games.

However, the development of other VR devices might very well solve them easily and

even increase the immersion at the same time.

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References Although most of the research done for this paper comes from many different sources,

these few are the most prevailing:

- For further readings on VR techniques and tips from developpers, I strongly

recommend GDCVault.com for all the Game Developper Conferences they held

and made available on their website.

- For news related to VR, I can recommend visiting roadtovr.com and uploadvr.com.

- For elaborated personal insights: medium.com with a search for „vr‟.

- Lastly, for free/paid games and experiences: wearvr.com and itch.io.

i Advanced VR Rendering with Valve‟s Alex Vlachos - GDC2015

https://www.youtube.com/watch?v=ya8vKZRBXdw ii No real source. Somewhere between the 660ti and 750. Just reddit comments. iii Foveated Rendering, RoadToVR http://www.roadtovr.com/a-pocket-guide-to-foveated-

rendering-from-smi/

iv Nvidias Gtx Titan X Pascal review, eurogamer http://www.eurogamer.net/articles/digitalfoundry-

2016-nvidia-titan-x-pascal-review

v Tabletop simulator vr trailer, BerserkGames Youtube

https://www.youtube.com/watch?v=KuUhWPUDpGo

vi Wikipedia, VR Motion Sickness - Kolasinski, E. M. "Simulator sickness in virtual environments (ARI

1027)". www.dtic.mil. U.S. Army Research Institute for the Behavioral and Social Sciences. Retrieved

22 July 2014.

vii Unreal 4 VR Best Practices,

https://docs.unrealengine.com/latest/INT/Platforms/VR/ContentSetup/

viii Interaction Design in VR, Vales Lessons. Yasser Malaika – GDC2015

https://www.youtube.com/watch?v=_vQo0ApkAtI

ix A look at the psychology of doing VR right. Kimberly Voll – VRGDC 2016

https://www.youtube.com/watch?v=-owQfn-iYQw

x Interaction Design in VR, Vales Lessons. Yasser Malaika – GDC2015

https://www.youtube.com/watch?v=_vQo0ApkAtI

xi A look at the psychology of doing VR right. Kimberly Voll – VRGDC 2016

https://www.youtube.com/watch?v=-owQfn-iYQw

xii Eagle Fligh Ubisoft, tech demo of movement,

https://www.youtube.com/watch?v=XzAgKgBEEAc

xiii Blacking out periphery to reduce motion sickness, http://arstechnica.com/gaming/2016/06/the-

cure-to-vr-sickness-might-come-from-blacking-out-the-periphery/

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Special Thanks Special thanks goes to l‟ENJMIN for lending me a Rift DK2. Thank you!