Virtual Reality

The article covers non platform specific topics. It revolves around limits and issues of the current generation VR.

What is VR ?

Virtual reality technology aims to create the illusion of being fully immersed within an artificial, computer generated world.

Regular video games already do it to some extent, because they let the player interact with a digital fantasy world and watch the results on the screen. The lacking ingredient is the experience of actually being inside the game. Virtual reality equipment is meant to fill that gap.

VR systems track body movements and convert them into corresponding actions within the virtual world.

The activity of walking is a bit problematic in this context. After all, you are supposed to be stationary in the real world and walk about inside the virtual one. The problem is solved by creating a designated area within which the VR system tracks the player or, to be more specific, his VR headset.

Tracking the headset’s position and orientation allows the system to know where the player is and in which direction he or she is looking. This information is then used to animate a digital representation of the player within the game. What this representation “can see there” is subsequently displayed on a screen mounted within the headset, right in front of the player’s eyes.


In the real world your eyes behave as two separate cameras and the ears as two separate microphones. There is a slight difference in what both eyes register because they’re located slightly apart from each other. The same thing can be said about ears. Those differences allow the brain to create an illusion of depth of view and give you the ability to tell where the noises come from.

VR headsets exploit those facts to improve the immersion. A separate picture is generated for each eye and a separate sound channel for each ear.

VR would be rather blunt if you couldn’t interact with the virtual world. Arguably the best way to do that would involve following movements of wrists and fingers. Other simpler solutions entail motion tracking of a handheld controller equipped with sticks, buttons and triggers. Each VR system makes use of differently designed controllers and in general works slightly different.

Press the relevant link to go to the specifics of each system: PSVR, Oculus Rift, HTC Vive.

Is it healthy to use VR ?

The main problem with VR is that it has a tendency to induce motion sickness, headaches and dry-eye syndrome. More on each of these in the sections right below.

In terms of the strain put on your eyes the headset doesn’t differ from watching TV, even though the display is much closer to the face. That’s because the lenses in front of the display make it feel like it is much bigger and much further away.

Having said that, it’s a new thing, so nobody really knows what side effects might be discovered in the future. I’m sure it’s wise to stick to the usual: DO NOT OVERDOSE !!!

What is VR motion sickness and how big a problem is it ?

Motion sickness is a combination of dizziness and nausea. It is triggered when the brain figures there is a disagreement between what it perceives visually and vestibulary. The vestibular system is a part of the inner-ear which detects acceleration of your body and direction of gravity.

If you are inside a cabin on a boat, visually nothing moves, yet according to your inner-ear the whole room rocks.

On the other hand, when you ride a roller-coaster in the VR world, the opposite takes place: you see a wild ride and your inner-ear detects nothing.

In both cases one might experience motion sickness, yet not everyone gets it, and not to the same extent.

According to one theory, this perception mismatch is interpreted by the brain as a symptom of intoxication. If that is true, throwing up is a life saving reaction. Unfortunately in the VR context it ruins the experience.

The following issues contribute to the VR nausea:

  • too high latency
    When you have your VR headset on, and you turn your head, it takes some time to update the display to the new point of view. This time gap is called latency.
  • low or unstable frame rate
    Video games produce a sequence of static pictures. Generating them fast enough results in the illusion of motion, very much like in the case of movies. Frame rate is a measure of how many pictures are generated per second.
  • juddery view in the virtual world
  • rapid acceleration or deceleration of the player in the virtual world
  • too much movement in the very close proximity of the player

The human brain can detect very small latency. However, if it’s below 20 milliseconds it’s generally imperceptible. All the high-end headsets have latency below 18 milliseconds, so it is not a problem.

In case of the frame rate, the high-end hardware is good enough as well (90 frames per second is a minimum), so everything depends on the game developers. They know what hardware is capable of, and it’s their job to optimise the game to get the smoothest experience.

There are a number of things a developer can do to mitigate the problem further. For example after the player crashes into a wall in the virtual world, instead of rapid deceleration and a mad camera spinning, the view can be faded to black, while keeping the pace of motion intact.

Another technique is an aperture which fades the peripheral view to black.

A good overview of the various tricks can be found in the presentation about development of the “Eagle Flight” game.

Even if games are well optimised, it can take some time to get used to the VR. One reviewer admitted he had horrendous motion sickness from the very get-go and it took him multiple sessions to get used to it. Many people report various degrees of nausea. It’s a very common problem.

If you have never used VR before, DON’T start with high paced games, especially those taking the player for a ride at terminal velocity. What I mean here is racing games, roller coasters, dog-fight games etc. Pick something slow and steady like Job Simulator and take it from there. Most people tolerate such games very well.

Another thing to remember is to avoid jumping between games which use VR differently. Predictably that makes nausea worse.

If you start getting sick, take a break right away. Trying to force yourself through it won’t work. Worse, it will make you unable to look at the headset, even from a distance.

Yet another piece of advice is to start playing seated and only for a couple of minutes. As you get more comfortable you can prolong your sessions and stand up.

It seems that it helps if you can see your hands in the game. To accomplish that you will need controllers, which serve as “virtual hands”. Each VR system has its own solution for that.

Also, nausea is less of a problem for room-scale VR. Turning your body instead of pushing buttons and sticks is obviously more natural way of changing direction.

Some people take pills against motion sickness. I would rather try to adapt slowly instead of taking chemical shortcuts.

In any case it’s a good idea to take at least 15 minutes breaks after every hour of gameplay.

Why VR induces headaches and how to avoid them ?

Everybody who wears glasses knows that after buying a new pair it takes some time to get used to them. In the meantime, they may cause discomfort and headaches.

If you are lucky enough not to need glasses, you might recall when you tried on the glasses of your grandparents when you were a kid. The world became fantastically distorted, yet the price to pay was discomfort and/or a headache.

The problems described above are caused by the fact that suddenly you start to see the environment around you differently than usual. This is obviously true when you view the VR, and it takes a while to adapt to it. However, if you don’t adjust your headset correctly you might get horrendous headaches all the time.

The most critical is the interpupillary distance (IPD). Before using the headset for the very first time, you MUST adjust it to your IPD.

Also, every time you use the headset, you should adjust the focus until you see the menu texts as clearly as possible.

One reviewer mentioned that he forgot to remove a protective film from the lenses of his headset. As a result the view was blurry all the time. Do not repeat his mistake !

Finally, don’t forget to take frequent breaks.

Why does VR cause the dry-eye syndrome and what to do about it ?

Many people seem to blink much less frequently with the headset on. That leads to dry-eye syndrome, so please REMEMBER ABOUT BLINKING !!! … and take frequent breaks !!!

This seems to be quite serious, so don’t take it lightly.

Is VR of any use for people with vision in one eye only ?

People with this condition are unable to experience depth of view (stereoscopy). With the use of VR, depth of view is a bonus, not a must, so it is not a problem.

What are the limits and issues of the current generation
VR ?

The issues described in this section are pertinent for all high-end VR systems. The comparison between high and low-end VR can be found in the chapter right below.

Limits:

  • the headsets are wired
    That reduces the immersion, especially for systems supporting room-scale VR.Using TPCAST wireless adapter you can make your HTC Vive or Oculus Rift wireless. It is expensive and not reliable enough, though. Vive is about to release their own wireless adapter soon. Hopefully it will be better than TPCAST.
  • The quality of the visuals is not as good as for HDTV
    VR objects which are “far away” or outside of the sweet spot in the center of the screen are blurry. You will also struggle with reading small text.
  • screen-door effect
    If you want to see it, you will. It’s not too bad though – most people quickly forget about it.
  • limited field of view
    You can see the boundaries of the display.
  • there is not a huge amount of top quality content in comparison with the regular games universe. This is changing as we speak.

Inconveniences:

  • sweating
    VR headsets cover a fair bit of the head and face so you should expect some extra sweating, especially on warmer days or while playing intense games. To remedy this you may consider using a fan.
  • lenses of the headset sometimes fog up
    Sometimes after putting the headset on, the lenses fog up. This goes away by itself, so it’s not a massive problem. If you find it annoying, you can use an anti-fogging spray.
  • women beware: VR headsets ruin the hairdo and makeup

Things to remember:

  • If you leave the headset exposed to the sun, the light going through the lenses gets focused on two particular spots of the display. This can cause irreversible damage.

Click on one of the following links to find the issues specific for PSVR, Oculus Rift and HTC Vive.
Get back to the table of contents of the chosen review: PSVR, Oculus Rift.

What are the downsides of the low-end VR in comparison with the high-end ?

Low-end VR systems use a mobile phone as a screen. If you already have a suitable phone, you can get a very cheap headset to get a taste of VR. The cheapest one in this space is probably Google Cardboard VR.

Limits of this approach:

  • no positional tracking
    you can look around, but there is no way of passing your position in space into the device;
    that makes it less suitable for games
  • usually there is no mechanism for adjusting the headset to the distance between your eyes,
    that may result in VR headaches
  • VR drains battery of a smartphone quickly

As of May 2018 you can also buy a standalone VR headset which requires neither PC nor gaming console nor a smartphone. At the moment there are two systems available: Oculus Go and Mirage Solo.

Back to: PSVR, Oculus Rift.

Why Does VR For A PC Require An Expensive Computer ?

For a smooth experience in the case of a regular game, a framerate of 30 frames per second doesn’t hurt that much. VR games require 90 at least, otherwise they make most people sick 🙁

This happens because there is a big difference in how the brain perceives a TV screen and something which looks more like reality.

If there is a slight delay between the actions you take and their counterparts in VR, this usually produces discomfort and motion sickness.

A powerful enough PC reduces these delays to the levels which are imperceptible to your brain.

VR requires the view from two different cameras at the same time, one for the left eye, the other for the right one. Only then it is possible to obtain a depth of view. Obviously this means twice as much work for the graphics card and given the restriction of at least 90 frames per second, it has to be a very fast one and thus expensive.

Back to: Oculus Rift.

 

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