quote:

---

This is actually something hard-core gamers have known for years. Motion sickness is caused by your brain interpreting the signals from your eyes as a rapidly moving event (like the air boat sequence) and not being able to corellate those same signals with your non-moving body. We saw it all the time in static flight simulators and it's a reason why most are now fully articulated.

The feeling is increased if the game you're playing is highly realistic. So the more you get into the game the higher chance of motion sickness. Take a look at this EULA statement from another game (I'll bet HL2 has one also):

Motion Sickness Statement

This Software generates realistic images and 3-D simulations. While playing or watching certain video images, some people may experience dizziness, motion sickness or nausea. If you or your child experience any of these symptoms, discontinue use and play again later.

---

quote:

---

There are a number of video games called "first-person shoot-em ups" and 3D environments - typified by the classic games DOOM and Black & White. The game engine creates a complex environment, or Virtual Reality, where first person perspective changes at the touch of a mouse or cursor. But these "first person perspective" games generate frequent dramatic perspective changes while the body remains stationary. In the game, the "player" can quickly whip the image through 180 degrees of scenery.

The result is a first-rate case of "car sickness" - the most common effects of simulator exposure resemble the symptoms of motion sickness: general discomfort, drowsiness, pallor, sweating, nausea, and, occasionally, vomiting.

...the U.S. Army has classified as "simulator sickness".

Display flicker (CRT refresh rate) reveals that flicker is something to be avoided if at all possible since it is distracting, induces eye fatigue, and appears to be associated with simulator sickness.

Several aspects of the visual display affect the perception of flicker. Of these aspects, those most applicable to the visual displays of virtual reality systems are refresh rate, luminance level, and field-of-view.

---

quote:

---

I figured it out...HL2 defaults to a low hertz. Although I had my ATI control center set at 1152x864 and 100Hertz in-game I was not seeing anything over 60.

So...all I did was add this line to my Launch Options (in properties): -w 1152 -h 864 -refresh 100

-----------

This is not a problem with the refresh rate. Headaches will result from a low refresh rate, but the nausea is caused by your skewed perspective. HL2 uses an unusually low FOV (field of view/vision) of 75 degrees. Most FPS games use a default FOV of 90.

To change your FOV you need to do the following:

Add '-console' to your HL2 shortcut (in Steam right-click on HL2, click properties, click Launch Options..., type '-console') without the apostrophes.

Open HL2 and type the following into the console:

sv_cheats 1
default_fov 90
fov 90

That should fix the problem. If it doesn't, try this:

Create a file named "autoexec.cfg" in your "..\Half Life 2\hl2\cfg" directory, open the file with notepad, and enter the above three commands on separate lines. Then, save the file and start up HL2 to see if the problem has been alleviated.

The "autoexec.cfg" file doesn't exist by default. Just right click anywhere in the "..\hl2\cfg" folder and click "New-->Text Document" then add in the lines and save the file as "autoexec.cfg" That should load up the new FOV for you so you don't have to type everything in all of the time.

---

quote:

---

Originally posted by Remus
I got my first motion sickness related to game when playing Wolfeintein 3D.

---

quote:

---

Hi xxx,

Thanks for writing. I'm glad that you've been enjoying Half-Life 2. As for the FOV questions: very early in HL2's development as our world got more detailed and fully realized we ran into some interesting issues that caused us to shift the FOV. Sometime in 2001 or early 2002 we made the decision to move to a tighter FOV, settling on 75 after some extensive testing. While FOV 90 is perhaps more representative of our visual experience in some ways - especially taking peripheral vision into account, in general a tighter FOV felt more accurate and appropriate for rendering the world and the objects in them given the goals we were pursuing in Half-Life 2. For example:

1) Characters all seemed frustratingly distant in FOV 90, and if you really tried to move up as close as possible to them, they'd be viewed with ugly wide-angle distortion on their faces - giving the experience an unpleasantly distorted or hallucinatory quality. And of course it was extremely unflattering to the characters!

2) Architecture and spaces feel oddly and unnaturally huge at FOV 90 - structures are unnaturally diminished at a distance, and it feels as if the player is moving at great speed through the world. In addition, every turn of the player's head emphasizes the distortion inherent in this wide-angled rendering, as objects move from the less distorted center to the extremely distorted edges of the screen.

We've been rigorously playing and testing Half-Life 2, Counterstrike Source and Half-Life Source for a long time now - and we've found nothing to suggest that the FOV change is a significant factor in causing motion sickness. We have, however, put a great deal of work and attention into reducing the motion sickness that can be experienced in the vehicles in Half-Life 2. During our early playtests, many of us were experiencing motion sickness from driving the buggy and the airboat - especially the airboat. We've done a lot of work on tuning the experience to reduce any ill effects - especially looking at how we manage the players head/view in relationship to the movement of the vehicles. Interestingly, for all of the vehicle sequences we revert back to FOV 90 so that you have more peripheral vision which is helpful when moving at these faster speeds. Even so, some people still do experience some motion sickness effects from long stretches in the vehicles - personally, I find that I am most affected by the intense jarring that occurs when you slam into something in the airboat at high speed - like when you miss a jump or something.

Thanks for the kind words about the game!

Best wishes,

Bill Van Buren
Valve

---