MTBS' VR Settings Guide

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Introduction

Now that the Oculus Rift kits are getting in game developers'...and let's face it...gamers' hands, there is a serious concern to be aware of. With a stereoscopic 3D display like a TV or monitor, it's very easy to see the left and right perspective at the same time and quickly make adjustments so your S-3D gaming experience is a comfortable one. Unfortunately, we don't yet have the ability to do the same thing with a Head Mounted Display like the Oculus Rift. We can see some interactions that are cloned on our computer display, but it doesn't really tell us anything useful.

This is a serious issue because if the settings are wrong, the gaming experience will not only be unfulfilling, it will be needlessly painful.

Vireio Perception Logo

While many game developers are planning dedicated VR support, a lot of consumers are enjoying immersive games today with the open source Vireio Perception drivers.  Unlike a dedicated VR game, drivers can run by the seat of their pants, and gamers really need at least some understanding of how 3D works so they can comfortably play their games and get the best results.

This step by step guide will tell you everything you need to know to get your games running with stereoscopic 3D drivers in the most comfortable and effective manner possible. While it won't solve problems like game or driver bugs, we think this will enhance your VR experience immeasurably.

These techniques only apply to drivers that use true left and right camera stereoscopic 3D rendering (e.g. The Vereio Perception drivers). 2D+Depth or 3D rendering based on a single camera view isn't the same type of 3D, and we don't know if these recommendations will be applicable.






The Stereoscopic 3D Map

Before we talk about head mounted displays, it's important to understand how 3D monitors work. Here is a top view diagram of how your eyes interact with a virtual 3D video game environment with an S-3D display:

The Stereoscopic 3D Map

Circles "L" and "R" are your left and right eyes.

The "S" line is the virtual screen glass. Professionals call this "Zero Parallax", but we will call it the "Neutral Point" because everything behind this position appears in the distance, and everything in front of it is an out of screen effect and will appear to pop out at you! Lots of fun! This is a virtual line and is not representative of your monitor's physical screen location.

To make this easier to follow, symbol "D" refers to "distance", and "P" refers to "pop-out".

Let's see how everything relates!

First, the boxes all represent the same object, but from different 3D perspectives. Remember that when you are wearing 3D glasses, your left and right eyes each see a unique 2D image, and your brain combines the two to create the 3D experience. This diagram is showing what things look like without the 3D glasses on so you can follow the relationships.

Box "N" is your object at the "Neutral Point" or "Zero Parallax". If you were looking at this with your naked eye without 3D glasses, it would be a single box because there is absolutely no separation to create a 3D effect. If this was the only thing on the screen, it would appear to be 100% flat.

Box D(L) and Box D(R) is the same box with a space in the middle. This space is called "separation", and the 3D distance is determined by the amount of separation between D(L) and D(R). If you were wearing 3D glasses, your brain would take these two images, consider the separation between them, and create a deep 3D experience for you.

Notice how D(L) and D(R) are aligned with your left and right eye? For the depth sensation to work, it is important that the image matches the eye that is seeing it. For example, if you open just your left eye, you will see D(L), and if you open just your right eye, you will see D(R).

It is important that the separation does not go beyond the actual space between your eyes or you will experience something called "divergence", or encourage your eyes to point uncomfortably apart from each other. Also, the space shown in this diagram is exaggerated in two respects. First, the separation is usually no more than an inch to two inches apart for distant objects. Second, when the images have the same separation as the distance between your eyes, it is as though you are looking into infinity which is unlikely to happen in your video game experience.

P(R) and P(L) is also the same box, but if you were wearing 3D glasses, it would appear to be popping out at you! How is this feat accomplished? If you look at boxes P(R) and P(L), their perspectives are crossed from D(L) and D(R) – everything is opposite! If you opened just your right eye, you will see P(R), and if you open just your left eye, you will see P(L). In both cases, these are opposite perspectives of where your eyes are accustomed to seeing things.

Separation impacts this pop-out effect too, and the space between P(R) and P(L) tends to be less than D(L) and D(R) because the pop-out will be distracting and unattractive if overused.

When you are using your stereoscopic 3D solution, you will have the flexibility to choose where line S or "Zero Parallax" is so you can have the 3D experience that is right for you.




Differences Between Stereoscopic 3D Displays and Head Mounted Displays

Neil Schneider, CEO of MTBS, in front of 150" Panasonic 3D Ready plasma.
The beauty of a 3D monitor or television is that there is plenty of room to customize the experience. By moving the cameras apart (the "separation") and adjusting the convergence to your liking, you can have a depth experience where you are seeing straight into the scene like a car windshield, you can have a lot of out of screen experiences where things seem to reach out and grab you, or you can have a mixture of both. S-3D monitors really are magic computer game windows if you know how to play with the separation and convergence settings for the best 3D effects.

Oculus Rift PhotoCrop Contest Entry

Head mounted displays need to be handled very differently. The principles are similar, but our personal biology and eye placement suddenly becomes a lot more important. We can still get a rich 3D experience, but we no longer have the flexibility to spread the separation apart the same way, and the convergence setting is no longer about choosing what is inside the screen and what's grabbing hold of our collar!

We have to remember that the whole goal behind an HMD is to be an immersive display that closely resembles how we see things in real life. In life, we don't have cameras, we have eyeballs! An HMD's lenses are practically pressed up against our pupils which means we can't move our eyes further apart or closer together (that would be a gross trick), and unlike a 3D display which can be placed a distance away, HMDs place greater pressure on our eyes to rotate according to what they see.

Therein lies the problem! When we put our HMD on, each eye is seeing a separate image that we can't easily compare, and we could be inadvertently forcing our eyes to diverge in uncomfortable directions without even realizing it. This is a no-no!

Therefore, the separation of the game's cameras is determined by the distance between our eyes. This measurement is known as the Interpupillary Distance (IP). When choosing our game settings, we have to figure out a way to make sure our eyes never have to look at something that goes beyond our IP and point outward.

Also, with a 3D monitor we were happy to go crazy with our convergence and have objects fly out of our screens because it's fun and it looks great! With an HMD, this technique no longer makes sense because the lenses are up against our eyes which means there is no screen for things to fly out of. We instead see things as we would in real life with our own eyes. We will still want to avoid that flying hatchet, mind you - we just don't have to use the same tricks to get the same results! If we did force a high convergence setting, it not only wouldn't be necessary, it would make the viewing experience painful to watch because our eyes would be forced to point inward.

Convergence is still an important adjustment, just not for the same reasons. Stereoscopic 3D effectiveness is best demonstrated with up close objects. If I were to take a 3D picture of an apple on a table with a stereoscopic 3D camera and overlap the images, it would be very clear that each view is very different. It's these differences that make the apple look interesting. If I took a picture of the same apple from far away, that part of the picture would look as though it could completely overlap. The aspects of 3D where you see the curvature of objects and fine detailing really happen up close, though you still maintain that chasm-like depth for objects in the distance.

With an HMD, the purpose of the convergence setting is to make sure we see that fine detailing up close, we still benefit from the depth in the distance, and we do so in a way that doesn't make our eyes twist and turn in painful ways.










Calibrating Vireio Perception Drivers


"Infinity" refers to the point in the scene where your eyes are pointed straight ahead and have no need to point outward. We have to be 100% certain our eyes are not being forced to point outward because that is considered "divergence" and is both uncomfortable and painful to experience.

1. Press CTRL-I to activate the Schneider-Hicks Optical Calibration Tool (S.H.O.C.T.).
Activate SHOCT!
In "Separation" mode, two vertical lines will appear; one for each lens. While looking straight ahead, open one eye at a time, and move each red line to the dead center of each of your eyes.  Use CTRL-O and CTRL-P to control the left line, use CTRL-K and CTRL-L to control the right.  While estimating the location according to what you see, ignore the game's crosshair and HUD because this may not actually be perfectly centered on each of your eyes.

Now that the SHOCT lines are properly set, we have the information we need to determine the best and most effective settings for your VR gaming experience!


2. Time to Separate
Not enough separation!
As you increase the separation, the distant objects in the left lens should move left, and the same objects in the right lens should move to the right. If you reduce the separation, the opposite happens.

Open JUST your right eye, and overlap the SHOCT line over a far steeple or the edge of a distant building. Don't move your mouse or head tracking once this is achieved!

Now close your right eye, and open your left. If the object is to the left of the SHOCT line in your left eye, then the separation level is too high. If the object is to the right, then the separation needs to be increased to add the sensation of depth. Gradually reduce and increase the separation while alternating between your eyes to get the image to appear on both SHOCT lines.

As you are increasing or reducing the separation, you will need to reposition the right SHOCT line on the object so you are getting an accurate measure between the left and right view.
 
Hit CTRL-I until the SHOCT lines are turned off. If the imagery is still uncomfortable to view, don't panic because we haven't finished yet!

HINT: If you are using an Oculus Rift, you can set your computer up to have the left/right view appear on your computer monitor at the same time as your HMD. After the SHOCT lines are set, they can be used as a reference point. Thanks to this calibration technique, you can easily see if the objects are properly placed even without wearing the Rift!

3. Converge, Converge, Converge!

Even though the separation is set, the game can still be uncomfortable to play if our convergence isn't properly adjusted. Have your game character walk to a corner of a wall or table. It's important that the object is easily viewable in the center of the screen.
Reasonable convergence setting for an HMD.
Press CTRL-I until you are in "Convergence" mode.  There will be a blue SHOCT line in each eye.  The right eye is a single vertical line, while the left has a vertical line, plus horizontal markers.

Do your best to find a vertical object standing at a 90 degree angle.  The corner of a wall or table is best.  Align the SHOCT line in the right eye flush against the object's edge.  Now looking at the left eye, you will see where the object's edge is relative to the 0 parallax line.  While we recommend trying to set this to 0 parallax, it could also be attractive to set this to negative one or two basis points.  You will have to experiment with each game.  Remember that positive convergence means into the screen, and negative convergence brings things out.  With an HMD, it's recommended to be modest with the negative convergence.

HINT: Thanks to the convergence SHOCT lines, you can take your HMD off so you can see what is happening and make more accurate adjustments.  As you are setting convergence, you will need to regularly realign the right eye with the SHOCT line!


4. Final Checks and Balances
Properly calibrated separation settings using SHOCT.
Turn the SHOCT lines on again by hitting CTRL-I. Choose an object in the far distance, and again adjust the separation so the same object in each respective lens is overlapped by a SHOCT line.

Again, walk to the table or wall corner and make sure it is converged as you intended. This is just a precaution as it's unlikely you will have to readjust this.

If there is any remaining discomfort, gradually reduce the separation setting.  Using your eyes shouldn't be painful, so don't try to force things!  When in doubt, turn the SHOCT on to quickly check that the separation of distant objects are in line with what your eyes are accustomed to.  Game environments and camera views can change, so be prepared to re-adjust and compensate.

That's it!




Calibrating Generic 3D Drivers

The generic technique should work with head mounted displays that are using drivers that don't have the SHOCT feature.

Remember that "infinity" refers to the point in the scene where your eyes are pointed straight ahead and have no need to turn outward. We have to prevent our eyes from pointing outward (i.e."divergence") because it's both uncomfortable and painful.

In this part of the guide, when we are talking about the lens center, we are talking about what our eye sees as the center, and not the actual hardware or shape of the glass. As all our eyes aren't the same, what is considered "center" could be a little different for everyone.

1. Find a suitable environment

Try to find a place in the game where you have buildings or tall objects in the far distance.

2. Turn Off the Crosshair
Lose the crosshair if possible, locate a far away object.
If it's easy to do, turn off the game's crosshair. Part of this technique requires us to see past what we are looking at, and the crosshair can be misleading.


3. Align your RIGHT eye

Open JUST your right eye, and place a far steeple or the edge of a distant building in the center of the lens (what your eye considers the center of the lens!). Don't move your mouse or head tracking once you have done this!

4. Compare to the LEFT and adjust separation!

Open JUST your left eye. Look at the edge of the object you are paying attention to while separating. If it's to the left of the screen center, the separation is too high. If it's to the right of the screen's center, then there is room to separate more.

While making separation adjustments, regularly align the right eye's object edge so you are getting an accurate measurement to the left eye's equivalent.

5. Converge, Converge, Converge!
Reasonable convergence setting for an HMD.
The game can still be uncomfortable to play if our convergence isn't properly adjusted. Have your game character walk to a corner of a wall or table. It's important that the object is easily viewable in the center of the screen.

Using the convergence hotkeys and alternately opening and closing each eye, do your best to get the edge of this wall or table corner to match up. It's acceptable if the left view crosses or overshoots the right (converges), but it can only be by a little.

6. Final Checks and Balances

Again look at a far distant object or building edge and have it placed in the center of the right lens and compare to the center of the left. Carefully adjust to make sure the object isn't going beyond the boundaries of the center of each lens (not to the left of center in the left lens, and not to the right of center in the right lens).
Properly Calibrated VR Settings With Generic DriversWalk to the table or wall corner and make sure it is converged as you intended. This is just a precaution as it's unlikely you will have to readjust this.

If there is any remaining discomfort, gradually reduce the separation setting.  Using your eyes shouldn't be painful or tiring, so don't try to force things!  Game environments and camera views can change, so be prepared to re-adjust and compensate.

That's it!



Conclusion

The Vireio Perception drivers are still a work in progress.  If this technique isn't working as expected, here are the leading causes and solutions:

  • The images are reversed.  Reverse them with the F6 key.
  • The convergence is WAY off.  This often happens because basic settings info hasn't been included with the game profile.  Try playing with the convergence settings until the separation behaves more predictably.

The above issues are temporary because as the drivers develop, profiles will be recorded with the required information to work from.

Thanks for reading MTBS' first VR settings guide.  We hope that these techniques will make it easier for you to find comfortable settings with your games and drivers.  We went through a deep learning curve in finding a solution that is easy to follow and use, and this guide will likely get updated with time as more software and hardware products get released, and we received feedback and ideas from fellow VR and 3D gamers.

Special thanks to John Hicks for programming the Schneider-Hicks Optical Calibration Tool (S.H.O.C.T.) in the Vireio Perception drivers.  It's the mark of a good (miraculous) programmer that he was able to implement the software ideas without actually owning a Head Mounted Display or 3D solution of his own!

Thanks again!  We look forward to your comments.