Out of curiosity, I picked up a Google Cardboard VR unit a few weeks ago. I thought it seemed crazy to slap your phone into this cardboard box and get a VR experience, but then I tried it out. Most people already have some understanding of how Virtual Reality (VR) works, with each eye being shown it’s own image, fooling the brain into creating a ‘3D’ representation of an environment. It’s been around for decades in simulators, rides, medical/military applications and more, but prior to now, it had never been this accessible.
Google Cardboard and VR
Until last year, consumer application of VR was extremely limited. High-costs of 3D setups have greatly limited the spread of VR into average user’s hands. 3D TV, which at one stage was heralded by the TV industry as the next big thing, has failed miserably, mostly due to lacklustre performance, fiddling, and lack of content. The solution had to be very affordable and easy-to-use. What easier way than to make our smartphones, which already have very high pixel density, all the sensors to track motion accurately, and and apps to boot?
At the Google I/O conference in mid-2014, Google released the first Cardboard unit, a self-assembled cardboard frame in which you place your smartphone and run the supplied apps. I’d highly recommend watching the official Cardboard presentation by the project engineers. You can also watch the 2015 update here. The 2014 presentation goes into detail on how the lenses and magnet-based button works, which is ingenious.
They also released a Cardboard SDK for developers to implement VR in their own apps, and the blueprints for making Cardboard, allowing the market to be filled with every variation of Cardboard design possible, nearly all priced under $10. The basic ingredients to get it working are:
- An Android or iOS smartphone with an accelerometer, preferably a gyroscope as well.
- A slot to insert your phone into, preferably holding your phone snugly as you spin around.
- Two non-adjustable lenses, which limit the area of the phone’s screen your eyes can see, and increases that area to fill your field of view as widely as possible. A fisheye / pincushion effect results, but software allows for balancing of this.
- A frame for blocking light out.
- A magnetically help slider/button on the side. Movement of this button triggers the phone’s magnetometer, as the screen cannot be reached during use. Version 2 of Cardboard (2015) instead has a push button system which levers another piece to touch the screen instead, as some phones did not function correctly to sense the magnet.
- Some versions, like the one I have, have an optional head-strap or NFC sticker. The former is useful is you plan on wearing the unit for a while, and improves immersiveness. The latter is not very useful at all.
- Cardboard V2, which was announced recently, fits phones up to 6″ (where the original version only fits phones up to 5.5″), has a non-magnet based button, and is easier to assemble. However, they are probably alot harder to get a hold of right now.
More than a million Cardboard units shipped out since then. It’s incredibly cheap and it allows people to get a taste of what a VR experience is like, using their own smartphones which they already have. It’s important to keep this in mind, when comparing to far more capable units up the chain, from the Samsung Gear VR, to the $350 Oculus Rift. It’s not really intended to compete with high-end VR units, which offer a far more immersive and beautiful experience.
Does it actually work?
Yes it does, mostly. Despite the small lenses, there is a degree of immersiveness that exceeds watching a flat screen, as head movements directly affect the image. During 3D scenes (not to be confused with flat 2D + VR scenes), I found that the objects had a proper feeling of depth, and viewing Photosphere pictures gave the impression of being inside the sphere itself. Most of the games required either pointing at an option for an extended time to select it, or using the magnet button to select it, which was not particularly responsive.
It reminded me of a 3D headset I had last time when PC gaming, which allowed the NVidia card, when hooked up to special glasses, to flicker the left/right lenses in time with the disparate images on the screen. I remember playing Action Quake 2 and marvelling at how ‘present’ the dead bodies looked on the ground. Naturally, this method was a lot easier to get running, and provided better results.
After installing the Google Cardboard app, I had a look at some built-in 3D models, photospheres, a tour guide of a museum and a 3D story with a mouse wearing a hat. The Play Store also had a surprisingly large array of Cardboard-ready apps, the better ones I found were the VR Roller Coaster, Insurgent (a 3D film-style story), Village VR, Tuscany, Brian the Ball (a 3D platformer) and Seaworld VR, to name a few. There were plenty more which I didn’t try, though some did look quite thorough. You can also view photospheres by renaming them with the prefix “PANO_” (no quotes) and dumping them on your phone somewhere.
Interpupilary Distance (IPD) is Important
When I first put Google Cardboard on, everything I saw was in double. At first I thought it was a software issue, but on further research, it turns out that it’s all to do with the IPD. This is the distance between your pupils, directly measured across. Ideally, they should match the distance between the center of both lenses as well. However, as we know, the lenses in Cardboard are not adjustable, they’re usually fixed at a distance of 60mm, where my eyes are substantially wider. When the two are dissimilar enough, the resulting images are too far apart, and your brain can’t process them anymore, leading to double vision. You can measure your own IPD, here’s how. It’s usually about 64mm for men, 62mm for women.
The solution, fortunately, is simple. Google has released an online facility to customize the Cardboard specs in software. You can enter the specifications of your Cardboard device, and the site will spit out a QR code for you to scan with your phone. From that point on, any app which uses the Cardboard SDK (which is most of them), will take the compensated values into account. This worked well for me, with no modification required of the Cardboard unit itself. You can try my values here, or create your own. With a bit of trial and error, you can even add correction for different lenses, eye sizes and phone cases.
What are the issues?
There are a large number of issues, many of which apply not just to Cardboard, but other VR applications as well. In listing them, I’m aiming to also point out the challenges which face VR at home in general.
As outlined above, getting your IPD settings dialed in correctly is paramount. Incorrect settings can lead to double-vision or disorientation or headaches. Nearly every headset that isn’t low-end like the Cardboard, has adjustable lenses, both sideways and fore/aft, to allow for optimum lens correction. For most people, I assume it just works out of the box, as the average human IPD is close enough to the lens IPD to work, I just have wide eyes.
The lenses on Cardboard are very small, approximately 25mm across, with a 45mm focal length and asymmetric in nature. Some of the cheaper versions used to be flat on one side, requiring the flat side facing the eyes, but these can be placed in either direction. However, the small diameter of the lenses result in a ‘tunnel vision’ effect, not terrible, but you can definitely sense the edges of the tunnel, similar to looking out with your face against an airplane window. Cardboard V2 has a 37mm lens for good reason. The Oculus DK2 can fit up to 69.5mm lenses, which are huge.
This is where things really fall apart. When your phone is 4cm (1.57inches) away from your eyes, suddenly that glorious Full HD screen looks like Minecraft mixed with Tetris. Massive blocky pixels reminded me of the 480 x 320 resolution on my HTC Hero. This is why Samsung recommend the Note 4’s 2560×1440 display for their Gear VR. For me, this breaks immersiveness substantially. It’s unlikely that we’ll be reaching a time where pixels are indiscernible anytime soon – at that short distance, your 5.1″ phone would require a resolution of 9600 x 5400 to achieve the 2190ppi to be perfectly smooth. Also keep in mind, that your phone needs to have enough grunt to render a 3D game in that resolution AND twice over, one for each eye, and you can see that it’ll be many years before we’re at that point.
Motion To Photon Latency (Lag)
Otherwise known as motion latency, is the time it takes for when you move your head, to when the image in front of your eyes adjust. In real-life, it’s more-or-less instant, and humans are expecting it to be that way due to our vestibular system in our ears. Once this motion latency increases, that weird lag / disconnected feeling occurs, and our brains become confused and suggests things like throwing up. Seasickness is an example, as it causes a disconnect between what our brain feels and what it sees. On our smartphones, this usually clocks in around 80ms. Oculus recommends a latency of under 20ms to be truly immersive, as does Samsung, and HTC with their Vive headset. This requires specialised hardware, and high refresh rates to cut out the bottlenecks. The lower the MTPL, the better.
Only really an issue with the Cardboard, for obvious reasons. Some people tape around the edges where it touches the nose, or put some foam to make it more bearable, but by no means is this a comfortable device for extended use.
If you wear glasses, this will affect the focal length, which might prevent it from working. If they’re large glasses, they might not even fit.
Partly due to the MTPL listed above, I found that I couldn’t use cardboard for more than about 15 minutes before feeling dizzy and disoriented, and a dull throbbing headache resulted. Frequent breaks are recommended, as can be seen in Google’s own physiology guide for VR here. Some things, like making sure there’s no light leaks, and using headphones, might alleviate the issue. I never used to get motion-sickness in FPS games, so I suspect the MTPL is more to blame here.
Would you recommend it?
Absolutely, if only just to get an idea of what VR can be like. Even simple things like Youtube (via 360 videos) and Photospheres take on a whole new experience when you can spin around and look in any direction, as if you were right there. Despite the many drawbacks, there is still no easier and cheaper way to get an idea of VR is really like for the average person. Anybody can order a Cardboard unit or clone online for a few bucks, install the free apps and be on their way, with just the smartphone in their hand. For devices like the Oculus Rift, a decent gaming PC and much more fiddling is required.
However a caveat, I’m still not entirely convinced that being ‘inside’ the experience of a movie (separate from a game or photosphere, where you normally have control anyway) is better than just watching it, just like when I watched 3D TV, or 3D Movies with the glasses. There is a certain direction that a linear story entails, and looking around detracts from it. It might make the objects and movement ‘seem’ more real, more present, but does that really improve the enjoyment of the movie substantially? Does improving the quality of paper in a book make it more enjoyable? Possibly marginally, but to me, the real enjoyment comes not from the fidelity or medium of the experience, but perhaps more from the meaning and message behind it.
Due to the unavoidable headaches I get from using Cardboard for any period of time, I’m filing them away in a drawer for the foreseeable future. Perhaps when device performance improves enough to reduce the motion latency I’ll be able to reduce the headaches. Not everybody is the same, with each person’s brain and eyes having a different reaction and sensitivity to being ‘fooled’ by the VR. The impression I get is that the majority of people are unaffected by this, so I suspect that a more responsive VR setup in the future would mitigate these issues.