Oculus Rift: DK1 vs DK2

A few weeks ago the very much anticipated Oculus Rift Development Kit 2 came out, and after a lot of F5 mashing I’ve received my device through the Post. Very eager I carefully opened the box to experience the next version of Virtual Reality for myself, and the experience was nothing short of impressive. However one can only truly understand how far the technology has come by comparing it to the previous development model, the DK1.

Luckily I am in possession of both devices and the DK1 works much better than when it was new, since now it runs newer firmware that fixes some of the orientation tracking bugs, thus I am able to do a pure hardware comparison and see how much Oculus has improved since releasing their first prototype to the world.

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Okay… what is this?

An excellent question! We should always talk about something, by first defining it and presenting it. The Oculus Rift (DK1 or DK2) is a head-mounted display that makes use of positional tracking sensors and a system of optical lenses to give the illusion that the wearer is actually within the virtual environment. Using a screen located very close to the wearer’s eyes, two images that are very similar to each other but have different perspectives are fed into each eye through the system of lenses and cover the field of view (FOV) of the user, thus creating the visual illusion that the subject is actually located within the virtual world.

Making use of the positional tracking, the in-game camera will imitate the subjects head movements in order to further enhance the illusion, making it believable from a visual point of view and with the aid of a pair of headphones the experience is complete.

For a more detailed explanation I highly suggest reading both the Oculus website and the Wikipedia article dedicated to head-mounted displays (HMD).

What’s in the box… and what is the box?

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Both devices come in their own carry and storage cases, making the storing and transport of the device very easy and accessible. Here, the DK1 wins over the DK2 as it has a much nicer, dark plastic case with an aesthetically pleasing design. When you’re opening the DK1 case to demo the Rift to someone it, you are making the statement: “you are about to experience the future my friend”.

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While the DK2 case is just a cardboard box with a handle… that’s it. This was done in an attempt to reduce production costs as Oculus VR wants to keep all the devices bellow the $300 price mark and while the DK2 does cost $350, the addition of a nice case would have probably bumped it up to $400.

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In both situation the cases are a very welcomed feature and a very useful tool for doing a demo. Because of this case I was able to demo the DK1 to family and friends that live abroad.

But what do we get? The rifts:

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Control boxes: the DK1 has another slight advantage here as you can control the brightness and contrast of the screen straight from the control box with physical buttons. You can’t do that with the DK2.

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Lenses:

DK1 comes with 3 pairs, while the DK2 comes with two but that’s because the second iteration of the Rift can be used even when wearing corrective eye glasses..

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Infrared camera only for the DK2 and some extra cables to connect it accordingly.

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Both devices come with, a fine cleaning cloth, very handy, as most people sweat a lot while wearing these devices which in turn causes the lenses to become blurry. They also include  HDMI to DVI adapters, HDMI cable, power brick and plug adapters for the power bricks to fit every country.

DK1 Accessories

DK1 Accessories

DK2 Accesories

DK2 Accesories

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And, of course, the ability to put the box on your head

Specifications

Let’s start off with the numbers on paper as this gives us the first impression of what we should expect from the next generation device in Virtual Reality:

DK1 DK2
Screen Resolution: 1280 x 800 1920 x 1080
Pixel Layout RGB Pentile
OLED NO YES
Screen Size 7” 5.7”
Screen Manufacturer               and model Innolux HJ070IA-02D 7″ LCD Samsung Galaxy Note 3
Latency 50ms – 60ms 20ms – 40ms (presumed)
Low Persistence NO YES
Refresh Rate 60Hz 75Hz
Orientation Tracking YES YES
Positional Tracking NO YES
Gyroscope, Accelerometer, Magnetometer YES YES
FOV 110 100
3D Stereoscopic Stereoscopic

“That’s nice dear, but what does all of that mean?”… I’m glad you asked! Since this type of device is rather new and a lot of the people out there have never tried one on before these numbers are completely meaningless, thus I shall proceed to split out the article into different sections, explaining most of the numbers above and the differences between the two devices in a more logical manner.

The screen and the lenses

The actual, physical screen size is probably the most useless out of the numbers in the table above, as it has no impact on the user’s experience with the exception of the weight of the device if the lenses are adjusted correctly, sadly this was not the case for the DK2. When it comes to an HMD the focus is heavily on the resolution, the display technology and the lenses so let’s talk about these and how they work together.

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The lenses are literally the entry point to the virtual world and their job is to help your eyes focus on a screen that is too close for comfort. The difference between the DK1 and DK2 lenses is quite significant, the later being a lot bigger, sit a lot closer to the screen and are a lot more powerful, as needed by the smaller screen size. This actually helps the device by making it a little lighter and a little smaller (in theory).

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The increase in circumference also allows for the ability to provide a bigger field of view, however in the DK2 this is limited to 100 degrees by the screen size itself.

The only thing still missing from the device is an adjustable IPD (interpupillary distance) for the lenses. I have an average-sized head so it’s not a problem for me, however my girlfriend has her eyes positioned a lot closer together, thus the focal point for her is not square in the middle of the lens. Because of this, she sees all the images blurry or distorted. I hope this gets addressed somehow in the consumer version.

Having gone through the lenses we reach the screen itself and this is where screen resolution comes into play. When the screen is sitting so close to your eyes, and is also enlarged by a pair of glorified magnifying glasses you will not only notice the pixels, but even the space between the pixels.

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Oculus comparison

Click to enlarge to see the comparison

This black grid between the pixels is known as the screendoor effect and the lower the resolution is, the more prominent it becomes. The following website does a very good job of demonstrating the difference in resolution and shows what the effect of Low Persistance technology has on the eyes, but it sadly does not portray an accurate representation of the screendoor effect. In the image above I have attempted to capture this effect on both the rifts. If you enlarge the second image you will see the space between individual pixels.

Another important factor is the display technology. In DK1 we have a classical RGB LCD screen, which makes the screendoor effect very obvious as it looks like a net in front of our eyes, with horizontal and vertical lines. By implementing a Pentile display in the DK2, the screendor becomes irregular, which actually makes it a lot less noticeable and vastly improves the reading experience.

The low persistence technology is also a very important improvement with the display that eliminates the motion blur effect experienced in the original Rift. If you are curious to understand how this technology works I highly recommend watching the video below as it explains perfectly what it is and how it removes the motion blur.

And finally the refresh rate. The DK1 screen works at 60Hz which equates to a maximum of 60 frames per second, the DK2 works at 75Hz which is a slight improvement but still has a little more to go to get to the recommended 90Hz for head mounted displays. The reason for these high frame rates is that jitter becomes very noticeable when your brain is ticked into believing that the virtual world is real. Every little bump that may become evident when moving your head really fast can immediately pull you out of the immersion, thus it is important to have a very high and constant frame rate in this type of devices.

Frontier Developments have included Oculus support in their new title Elite: Dangerous and when testing it internally with a DK2 they could only obtain constant frame rate at 75FPS on a GeForce Titan. On my 660GTX with graphics settings on low and 1080p resolution I can squeeze out 60FPS most of the time, but it’s nowhere near enough for the best experience the DK2 can offer, thus new and more powerful graphics cards will be needed.

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The Orientation and Positional tracking

For the orientation there is nothing too special. It’s the same gyroscope-accelerometer-magnetometer combination used by all the mobile phones out there. Both the DK1 and DK2 benefit from this combination of sensors to establish which way the user is looking, with the DK2 having a much higher refresh rate, taking a position sample at 1000Hz (that means once every millisecond) and feeding that back into the application to translate into in-game movements.

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Where the DK1 falls short is the positional tracking. The DK2 comes with an infrared camera and the HMD itself is covered in infrared LEDs that can’t be seen by the naked eye. By measuring the distance between the leds and their position in space, combined with data from the accelerometer, the DK2 can also replicate your head’s position within the game.

The difference is extremely noticeable, especially in a game that runs at the full 75fps where every little hang becomes a massive annoyance and lag cannot be an issue. With positional tracking the immersion becomes complete up until you lean forwards or to the side to try to look at something and you either: A. get the device outside the camera’s field of view B. smack your head on a real surface (I.E. a desk)

This camera does however add a lot of extra cabling to the rift so if you’re suffering from OCD this may throw a spanner in you chi.

The experience

When I put on the DK1 for the first time back in 2013 the result was ground shaking. Back then I didn’t know what to expect, this was the first ever I’ve worn an HMD. I was immediately bombarded with a feeling of magic and confusion. It was awesome and made me pull the trigger to buy a DK1 of my own. As the magic slowly died out I started noticing issues, the screendoor effect being the first one to hit me and it was the hardest punch. Immediately after the small resolution became an annoyance, then the fact that positional tracking is missing, the sickness feeling caused by the motion blur effect and finally how uncomfortable the device actually is.

Yet I chose to live with all the inconveniences mentioned above, as the experience of being transported into a different world was a lot more enticing than all the downsides put together. Thus a year passes…

It’s 2014 and a lot has changed: Sony announced they are working on their own HMD prototype and demoed it under the name Project Morpheus (I miss the Matrix too, Sony). Valve have also demoed their HMD prototype which, as they claim, was just a proof of concept and they are never going to release one to consumers. Oculus VR get bought by Facebook for $2 billion, accelerating it’s development, bettering the Rift and finally releasing the DK2.

I received mine 1 week after the shipping started and I honestly didn’t expect too much of it. The thing I was excited about the most was positional tracking but all its other features I didn’t care much for… at first.

Never the less it arrives and I happily go through the packing to get to my new rift. It was… difficult to set up. All the extra cabling and finding a good position for the camera, getting everything connected, installing the new SDK and the new drivers, understanding how the games work with it now, it was more of a hassle than expected…

(I predict that this will be asked so let me answer in advance: the games recompiled with the new SDK now generate a special executable that feeds the game straight into the rift. Gone are the days when you had to manually set up the device as another monitor and move the game around to fit in the rift or mirror your main display. This however doesn’t apply to older games and can be troublesome if trying to use the DK2 with a game that doesn’t support it).

…But it only took an hour to figure out in the end. So I load up the Tuscany demo and realized how wrong I was. Most of the issues the DK1 had are now gone! No more motion blur, no more sickness, no more lack of positional tracking, screendoor is not as noticeable and the text was now readable. The DK2 is not an increment over its predecessor, It is leaps and bounds ahead making the experience near perfect. If you try the devices one after the other you will think they are separated by a whole decade of research, not one year.

To test the motion sickness I asked my girlfriend, who is prone to car sickness, to try the Cyberspace demo with both the DK1 and the DK2 at a 30 minutes interval. She could not complete the demo with the DK1 on, taking the headset off after about one minute and thirty seconds, saying she felt sick and lightheaded. With the DK2 she could complete the demo without issues, saying they she felt slight lightheadedness after the ride.

The only improvements left, in my opinion, to make it consumer-ready are: 2.5K screen (4k would be optimal), lighter form factor which would result in improved comfort, and an adjustable IPD lens system (people’s eyes are not the same distance apart oculus!).

Conclusion

The DK1 was groundbreaking, the DK2 is revolutionary and the consumer version won’t be in stock for a long time. But you already know I like it, so let’s look at the experience some other people have had with it:


Howdy y'all! I'm a Systems Engineer working day (and sometimes night) to fix all of your VoIP communications problems but my heart resides with the over-captivating world of gaming. Although I can't say too much about gaming engines and raw usage of the GPU, when it comes to multiplayer LAN, WAN, MMO or CO-OP (local or otherwise) I'm your guy. Follow me on : Google + , Twitter, Facebook

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