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Racing Sims' DEFAULT SETTINGS CAN CAUSE VR SICKNESS & HOW TO FIX IT.

5/23/2016

18 Comments

 
I'm a big advocate of sim racing as a motorsport in its own right and also as a great training tool for real world competitors. For many racers, virtual reality has brought sim-racing to a whole new level and you hear many stories of elation from drivers after donning a VR headset for the first time and experiencing the cockpit of their favorite exotic sportscar as if they are really there.  For some however, that elation is short lived once they pull out onto the track and the first few corners make them start to wonder if they might be seeing their lunch again soon.  
​With the recent launch of the HTC Vive and the Oculus Rift CV1, more people than ever are going to be trying out driving in virtual reality for the first time, but unfortunately the default view settings in many sims might cause VR racing to get stuck on the starting grid.  These view settings are causing motion sickness in many drivers because developers have brought traditional sim racing camera views into virtual reality.  Due to the increased realism of VR, these default settings cause issues for many people because they are different from how we experience driving in the real world.

Locked Horizon
Traditionally, driving simulators handled the view as if a video camera had been placed in the car where the driver's head would be.  The sim racer's view on screen would be locked to the movement of the car.   Some developers would add in view shaking or smoothing, but for the most part, this is how all sims were done for years.  In early 2011 however, I started a petition on the iRacing message boards to add a feature to the sim where instead of the view being locked to the car, it would be locked to the horizon.  After a massive forum thread with people arguing both sides, iRacing added the feature seemingly begrudgingly at first, as it was a hidden setting in the app.ini file.   Eventually however, they added it as an in-game option.  A few other other developers picked up on this idea, and this view setting then became available as an option in simulators such as Assetto Corsa and Project cars.  Although it wasn't the default setting, it could easily be enabled in the game menus.  

These screenshots below from Project Cars show how these two different settings look when a car is on a steep sideways incline.   With a traditional sim-racing camera, the view is completely locked to the car and the horizon is seen to tilt.  With the locked horizon setting however,  the view is locked to the car on the X, Y, and Z axis, but locked to the track in roll and pitch.  The horizon remains level. ​As the car then goes over bumps, through banked turns,  down hills, etc..  the driver sees the car bounce and roll about, but the track appears to remain stationary.  This view setting is based on mimicking the way the eyes and brain perceive movement in the real world.  
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Enter Virtual Reality
With the release of the Oculus Rift DK2 in 2014, more sim-racers than ever got to experience racing in virtual reality for the first time and the horizon locking feature came into the spotlight again.  While some felt that the locked horizon view looked odd on a  flat screen in 2d, in virtual reality, many drivers report it as a much more natural way to drive and it alleviated the motion sickness often caused by the traditional camera view.  With certain cockpit based games such as Elite: Dangerous, the traditional locked to vehicle view is ideal.  The movement in pitch and roll is relatively smooth and slow and 360 degrees of movement is required.  You are essentially using the ship as a large gun that you sight with using the stick.   For the majority of VR games however, the view remains locked to the horizon.  Imagine playing a game such as Space Pirate Trainer if the view was locked to the gun instead of the horizon.  

​A sim-racing game is somewhere in between these.  On a smooth and flat track with a tightly sprung car, the difference in the two methods is not readily apparent.  As the terrain becomes increasingly bumpy and three dimensional such as in a rally sim however, the difference between a view locked to the horizon and one locked to the car becomes clear.  Project Cars owners should try out Horse Thief Mile with the two different settings.  The incredibly steep inclines are much more apparent with a view locked to the horizon.  As a driver development company, we train our drivers look ahead; to focus on the track and pay close attention to their movement in the world.  We don't want them to focus on the cockpit and car and use it as a gun-sight with the track as a secondary focus.  

As of this writing however, the locked horizon setting is not the default for any current sim and although long-time sim racers have often developed a tolerance to world movement, many first-time VR drivers experience motion sickness.   In virtual reality, the traditional camera view causes a driver to experience a track that heaves and pitches as the car negotiates the crests, bankings, and bumps. While this default setting did not often cause problems in 2D, the added immersion of virtual reality has brought to light for many drivers that the human eye does not act like a video camera and the traditional way that racing simulators have handled the view is not how we experience movement in the real world.
Visionary Science
The eyes and brain have evolved several fancy tricks that many people aren't even aware that they are experiencing.  The visual system in the brain is too slow to process images that are moving across the retina at more than a few degrees per second. Thus, to be able to see while we are moving, the brain must compensate for the motion of the head by turning the eyes.   Try this little experiment.  Look at an object and then start to move your head back and forth as if you are saying no. If you then increase the speed with which you shake your head, eventually your eyes won't be able to keep up and you will start to see the room move left and right.  You can also do this same experiment by tilting your head side to side.  Your eyes actually rotate in your head to keep the image level.  These eye movements that correspond to head movement are called the vestibulo–ocular reflex.  They act like a gyro-stabilized camera.

We also have eye movements called smooth pursuit and saccades.  Smooth pursuit is eye movement when you are tracking a moving object.  A saber toothed tiger running across a field for example.  A saccade is the eyes' movement as you look from one place to another.  Saccades are some of the fastest movements in the human body, but we don't experience motion blur because the brain does a neat little trick called saccadic masking.   Go stand in front of a mirror and shift your gaze back and forth from one eye to the other.  You can't see your eyes move because your brain filters out the movement so that you don't experience blur.  An observer can see your eyes moving back and forth however.

The end result of all these visual tricks is that when a driver negotiates a corner,  they will focus on a portion of the track for a second using smooth pursuit and then a saccade will move their view to the next focus point where they will then switch back to smooth pursuit.  If they hit a bump or tilt their head, the 
vestibulo–ocular reflex will compensate and keep the image stable on their retina.  But all their brain sees this whole time is an umoving track as the car bumps and rolls around in their periphery.   If you try to reverse this by making the car unmoving and instead the world bounces and rolls around, you just might have yourself a recipe for virtual reality motion sickness.
How to fix it
Below is a list of sims and how to enable horizon locking.  If there are any we missed or the method has been changed, please comment and we will update this article.

Project Cars
Under camera movement options, change all settings 0.    Under virtual reality settings change world movement and g-force effect to 0.

Assetto Corsa
Under options - view, enable the checkbox "Lock onboard camera to horizon"
​
iRacing
Under options - set roll and pitch chassis to 0%

Dirt Rally
In the folder   "drive":\Documents\My Games\DiRT Rally\hardwaresettings
locate the file called hardware_settings_config.xml and modify this line to the following

orientationLock="true"

This only works for virtual Reality mode, but a mod is available for standard 2d.

Live For Speed
Not currently Supported

I hope you enjoyed this article.  If you are interested in a complete guide to the physics of racing, we also offer The Science of Speed book series, available through our bookstore or at popular retailers such as Amazon.​

​by Adam Brouillard
18 Comments
Craig
5/26/2016 08:33:40 am

Great article. Thanks for this information.

Reply
Maggi
5/27/2016 02:42:51 am

I agree 100% and have been using "lock view to horizon" for many years. Not only for VR, but also for a triple projector setup.

There is no motion sickness with this option (which I assume can be seen as a sign that our brains perceive it as the more natural view).
We have to admit though that it work better with Road Racing as opposed to Oval Racing.

Reply
Shell_fr
5/27/2016 07:26:42 am

Woow! It sucks! I prefere realism, but this maybe good for people really sick, less realism but less sickness.

But if you have no motion sickness, don't do that! It ruins realism!

Reply
rinalduzzi pascal
5/14/2020 08:15:24 am

Your brain lock your view to horizon all the time. You can tilt your head in any position, your brain will lock it to horizon. That is the reality. On a movie or a video game, if the view is not lock to the horizon, you will have motion sickness, because your brain dosn't like this.

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Nereosis
9/15/2020 09:24:06 pm

If your brain automatically does it then making the game do it for you doesn't really make sense?

If you get motion sickness then yes turn it on. But if you don't then it's way better without it.

Adam Brouillard
9/16/2020 09:57:31 am

Your eyes and brain only does this in a real world scenario because of the effect of gravity on the inner ear. If a video game camera starts tilting the world, but the inner ear does not feel a change, then you can cause motion sickness as what you see and feel doesn't match. Here is a paper with more info.

https://www.cell.com/current-biology/pdf/S0960-9822(05)00837-7.pdf

JT
6/15/2016 01:10:53 am

Nice article. The illustrations you chose are very confusing though, due to a strange perspective of the road and the hills. In an article about perspectives, this should be better.

Reply
Adam Brouillard
9/16/2020 10:00:33 am

Hi JT, how are the images confusing? You can see the earth's horizon in the background in both images which shows the reference for the direction gravity would be working on the inner ear. In one image, the horizon is level and car is tilted, in the other image the car is level and the horizon is tilted.

Reply
Keith W
8/27/2016 03:39:01 am

Automobilista, rFactor, rFactor2.
These are not directly supported, but there is a plugin available on the internet, called RealHeadMotion by MagicFR, which does what you describe.
I find the default 'locked to vehicle' view very uncomfortable after a few laps, but if I use the plugin, which changes the view to 'locked to horizon', I am fine.

Reply
Michael
10/22/2016 03:15:25 pm

Hi there,

where can I find the mod for Dirt Rally to lock the camera to horizon (without VR)? I looked in the Workshop and on Racedepartment but there is no Mod like this available. Thanks

Reply
Matt
11/5/2016 05:17:40 am

Tried Project Cars in Oculus Rift with above settings, made me extremly ill in a matter of seconds, worse motion sickness I have ever experienced. Turning off motion blur worked better for me.

Reply
Grim
1/25/2017 08:03:40 pm

For people prone to motion sickness it might be some solution but for the rest it is just unrealistic! When you sit in any race car you are tightly strapped to the seat and your body movement is very limited so the view to car lock is not so far t\from the truth and in VR unlike on the monitor your head movement compensate for horizon changes. I think you are entirely wrong in your assumptions. I drive in my sim rig in Project Cars, Assetto Corsa, Dirt Rally, Live for Speed and others sims and always have view locked to car. I tried driving Dirt with default view (locked to horizon) and was very slow and my reaction time was so much worse until I switched to car locked. When driving race cars you simply can't lean left and right and up and down according to horizon! Also the G forces push you usually outside the horizontal line, out of the corner. For some it might be good but don't shove it down the throath of everyone becouse it isn't right!

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Paul Sexton
5/16/2017 04:17:32 am

Not sure I agree with the assessment in this article.. I think it is more of a subjective than an objective matter. I for example cannot stand the view locked to the horizon setting as it makes me VR sick almost instantly, the locked to the car works much better for me.

My findings also fall in line with the prevailing wisdom of cockpit VR games helping with motion sickness as the fixed cockpit around the player helps to "ground" them. When that cockpit starts shifting and moving around as if you're moving your head, when you're not, it makes for near instant motion sickness... At least for me.

Reply
Reiche
9/24/2017 04:28:24 am

Do the settings for Project Cars also apply for Project Cars 2, at least as a baseline?

Reply
James
10/1/2017 05:17:48 am

I can't believe I've only just discovered this setting in Assetto Corsa. I've been playing around with different settings for almost three years, gradually improving the feel of the game. Locking the view to the horizon has made driving so much more intuitive and provides a completely new and thoroughly enjoyable sim experience. What is your opinion on the g-force settings in Assetto Corsa? I've currently got them all set to 3x.

Reply
Aaron Voegele
4/14/2019 09:54:54 am

This actually makes me more sick for one reason: i use the horizon of the car as my "base". Basically, in my head, the car should remain static

Reply
Mark Ferring
7/19/2020 12:42:27 pm

Do you know if there is a way to fix the horizon on Codemasters F1 sim?

Reply
Nick Bell link
8/19/2020 04:44:54 pm

Man i wish i had read this when i owned a VR headset. I bought one specificly for getting back into racing. Couldnt handle it, 20 min carburettor cup on iracing felt like id done the le mans 24hr. Elite dangerous however, mostly a joy - couple of moments in asteroid field maybe. I ended up going back to tripple screen and selling to fund a rig, so i would have loved to have tried these settings. This article needs more people to see because i bet alot are/were in the same boat as me

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