A lot has happened this week in the Augmented Reality (AR) / Mixed Reality (MR) space. On February 29, Microsoft has opened up HoloLens Developer Edition preorders for a selected lucky few, and more importantly, published a ton of videos, white papers and developer documentation. This gave us an unprecedented amount of information to parse and learn a ton about the capabilities and limits of the device.

Meta – the other very interesting player in this space – has also opened up a few days later, on March 2. They also opened the preorder for their respective developer kit (devkit), the journalist embargo has lifted and for the first time, we got to see the Meta 2 glasses in action – at least on video.

In this post, I’ll try to piece together all the information I came across during these few frantic days of research. I’ll show what’s common and what’s different in Meta’s  and HoloLens’ approach, devices and specifications, and provide an educated comparison based on the data available.

Disclaimer

And this is the key. While I had about 15 minutes of heads-on time with HoloLens back in November, the device and its software has probably changed since then. As for Meta, all I have to go on is the data available from Meta itself, the reports of journalists and examining videos frame by frame to make educated guesses. I never saw a Meta 2 headset in person, much less had actual time using it. While I’m pretty sure what I’ll write about is fairly accurate, there are bound to be some inaccuracies or even misinformation here. If you find some of these or do not agree with my conclusions, please feel free to comment, and I’ll try to keep this post up-to-date, as long as it is practical to do so. This post will be a work in progress for a while, as more information becomes available and people point out my mistakes or perhaps Meta hits me with a headset to play with (hint, hint).

With that out of the way, let’s get started and see how Meta 2 and HoloLens compare!

To Tether or not to Tether

The Meta headset is tethered. The HoloLens is not. This may seem trivial, but in my opinion, this is the most important contrast between the two devices – and a lot of the other differences come down to it. So, let’s see what this means.

The HoloLens is a standalone computer – a fact that Microsoft is very proud of. Just like a tablet or a phone, it only needs to be attached to any wire is when you’re charging it. During actual use, you are free to move around, jump up and down, leave your desk or walk long distances. This kind of freedom opens up several use cases – walk around a factory floor or a storage space while the device shows you directions and which crate to open; go to the kitchen while keeping a skype video conversation going on the right and the recipe on the left; or bring the device up to the space station, and have an expert on Earth look over your shoulder and instruct you by drawing 3D pointers.

Meta’s tethered experience ties you to the desk (unless you strap a powerful laptop to your back, which has been done). You can stand up of course, but can only move 9 feet, and run the risk of unplugging the device or pulling your laptop from the table.

On the other hand, the tethered approach has great advantages. You are not limited to the computing power in your headset (which is about the same as a tablet or mobile phone). You can use an immensely powerful desktop computer with multiple high-end graphics cards and CPUs and an infinite power supply.

All of this power comes with great – well not responsibility, but additional cost. We’ll talk about pricing later, but let’s just mention it here that you’ll need a pretty powerful, gaming grade PC with an i7 processor and a GTX 960 graphics card to get the most out of the Meta 2 headset.

It is worth mentioning, that Meta is actively working to create a tetherless device down the road – but this post is about what’s been already announced, and the Meta 2 is tethered now.

Ergonomics, Comfort

One would think that Meta would have advantages on the weight front, since you don’t have to wear an entire computer and batteries on your head.

HoloLens weighs 579 grams. Meta’s headset weighs in at 420 grams, but that’s without the head straps and cables. I’ve no idea why Meta left out the head straps from the calculation, since it is definitely something your neck will have to support – but in any case, I’d estimate that weight-wise, the two devices are pretty much at the same level.

What’s more important for long term use is the actual way your head has to support that weight. I only have personal experience with HoloLens, but its weight distribution and strapping mechanism makes you forget all about the weight in just a few minutes. Both allow for glasses to be worn underneath them – something that is very important to me personally, and I suppose to a lot of other potential users.  Both have a ratchet system to tighten the straps around your head, although Meta’s ratchet seem to be very loud based on one of the videos. Meta also uses Velcro to adjust the top strap – I imagine that people with more hair than me may find this an issue.

 

All-in-all, I can’t decide whether the Meta or HoloLens is more comfortable to wear on the long run. My guess is that there’s not going to be extreme differences in this regard – not counting the Meta’s tethered nature, which is bound to cause some inconvenient moments until one gets used to literally being tied to the desk. There are also some potential eye fatigue issues that I’ll touch on later.

Software, Development

As mentioned before, Meta 2 requires a hefty PC – and it needs to run Windows 8.1 or newer. Meta behaves like a second screen connected to that PC through an HDMI 1.4 cable, so anything Windows displays on that screen will be shown to the user. It is up to the developer to fill that screen with a stereoscopic image that actually makes visual sense. The best way to do this is by using Unity – a game developer tool, which is quickly becoming the de-facto standard for creating virtual reality and augmented reality experiences. It’s been shown that you can also place Microsoft Office, Adobe Creative Suite or Spotify around you on virtual screens, and interact with them, removing the need to have extra monitors. How well it works in practice remains to be seen though, but one Meta engineer has discarded three of his four monitors in favor of holographic ones.

There’s not much more to go on when it comes to the development experience of Meta. They have time though – their devkit will not be shipping until 2016 Q3.

Microsoft’s HoloLens is a standalone computer, running Windows 10. The same Windows 10 that’s available on desktop, tablets, phones and even Xbox. Of course, the shell (the actual end user experience) is customized for every device. For example, this is the Start menu of HoloLens:

 

Running a full-blown Windows 10 on HoloLens has some distinct advantages. HoloLens can run any UWP (Universal Windows Platform) app from the same Windows Store that the phones, tablets and PCs use. This means that you can simply pin the standard 2D weather app right next to your window, and you can get weather information by just looking at it. Or pin a browser with the recipe to the wall above your stove. When it comes to running 2D applications with HoloLens, it is less about creating floating screens and windows around you (although you can do that too), and more about pinning the apps on walls, top of tables and other real world objects.

As for development, Microsoft, has just published an insane amount of developer documentation and videos, which I am still in the process of reading through. As you can expect from a software company, the documentation is very detailed and long. But what’s more important, the platform seems to be pretty mature, too. For example, I was just informed by my friend and fellow MVP, James Ashley that Microsoft has built an entire suite of APIs that facilitate automated testing of holographic applications.

For more involved development, the #1 recommended tool is also Unity. This is great news, since this will make a lot of the experiences created for one device easily transferable to another one. At least from a technical perspective, because – as I’ll detail more later – adapting the user experience to the widely different approaches of these headsets is going to be a much larger challenge. But a developer can also choose to create experiences using C++ and DirectX – technologies that even AAA games use. Not that you’ll be able to run the latest, graphically demanding games on a HoloLens hardware – it has a much weaker CPU and GPU, and performance is further limited by the fact that the HoloLens has no active cooling (fans), and will shut down any app that dangerously increases the device’s temperature.

If you do want to run AAA games on HoloLens though, you can take advantage of the game streaming feature of Xbox One. You can just pin a virtual TV on your wall, and stream the Xbox game to your headset. I expect to see similar techniques to stream desktop applications from your computer in the future.

Resolution, Field of View

Field of View is the area in front of you that contains holograms. With Mixed Reality devices, the FoV is very important – you want the holograms to cover as much of your vision as possible in order for them to feel more real. After all, if images just appear as you move your head, it breaks the illusion, and can make you feel a bit confused.

Ever since its introduction, HoloLens’ field of view (the area in front of you that can display holograms) has been under criticism. Some compared it to looking through a mail slot. Based on data available on the just released developer documentation, I finally have a way to calculate the FoV of HoloLens.

According to the documentation, HoloLens has more than 2500 light points per radian. Assuming that “light points” are basically a fancy word for pixels, this means that HoloLens can display approximately 43.6 points per degree. This is a similar measurement as DPI (dot per inch) for 2D displays, such as phones, although I don’t know how to scientifically convert between the two.

Another place of the HoloLens documentation states that it has a 1268x720p resolution (per eye). So, if we have 43.6 points per degree, and we have 1268x720p resolution, we have a field of view of 29.1×16.5 degrees, which ends up being about 33.4 degrees of diagonal field of view. If my calculations are correct that is. They may very well not be, since Microsoft has given us another number: 2.3 million light points total. 2x1268x720 is actually less than that (calculating with 2 eyes) – it is 1.826 million. So, there is a chance that my calculations are off by 20-30%. (Thank you James for bringing this to my attention).

Let’s see the Meta 2! Meta is not shy talking about their field of view, in fact this is one of their biggest selling points. Meta claims to have 90 degrees of diagonal FoV, which is not only 3 times as large as the HoloLens’, it is pretty much the same size as the Samsung Gear VR headset! 90 degrees is huge compared to pretty much every other AR device – most manufactures struggle to even reach 40-50 degrees.

For a larger field of view, you need more pixels to keep images and text sharp. Meta has a 2560×1440 pixels on its display that gets reflected into your eye. And that is for both eyes, so one eye gets 1280×1440, which is “only” twice as much as the HoloLens display. With a much bigger field of view though, we end up with about 21 pixels per degree, approximately half of HoloLens’ 43. This means that while the experience will be much more immersive, individual pixels will be twice as large. Whether it is enough remains to be seen – I haven’t read any complaints about pixilation though. One thing for sure: you’ll definitely want to move close to your virtual screens so that they fill your vision to read normal sized text. Also, the larger pixel count means more work for the GPU – another point where the tethered nature of Meta is an advantage, and one likely reason on why HoloLens has a limited FoV.

Here is a handy table to sum all of these up – I put the data I calculated / deducted in italic, and the manufacturer provided numbers in bold.

	HoloLens (could be higher by 30%)	Meta2
# of pixels per eye	1268×720	1280×1440
diagonal Field of View (degrees)	33.4	90
Pixels per degree	43.6	21

Interaction

An important way of interacting with HoloLens is speech. HoloLens is a standalone Windows 10 computer, and thus the applications you create can support speech commands and even integrate with Cortana. Technically, there’s nothing stopping you from using speech commands on Meta either, but this hasn’t been shown in the videos I saw – and you’d need a decent microphone on your PC. HoloLens has an array of 4 microphones that go wherever you go to clearly pick up your speech and filter out ambient noise.

Let’s talk about manipulating holograms, and activating buttons! Probably this is the area where the two products differ the most. Both HoloLens and Meta are able to see the user’s hand, and use what it as a gesture input, without needing to have any additional devices. (Although HoloLens comes with a Bluetooth clicker that has a single button you can press). However, that’s where the similarities end.

Meta thinks that your hands are made to manipulate the environment, and thus it should be the tool to interact with holograms, too. With Meta, you touch a virtual object to move or rotate it, push your finger forward to press a button, close your fist in a grabbing motion and move your hand to move things around in the virtual world. Meta wants to remove complexity from computing with this natural approach and direct interaction. Direct interaction (touch screens) is what made phones and tablets so popular and easy to understand as opposed to the indirect model of a computer mouse.

This is a great concept on paper, but if the reactions of the journalists who actually had hands-on time with the device are something to go by, needs more refinement until it actually works the way Meta intended. Engadget says this “feature didn’t work great… the gesture experience needs to be refined before it launches”. TechCrunch calls the hand tracking control “a bit more brutish than I would hope”, and praises Leap Motion’s technology in comparison (Leap Motion specializes in 3D hand tracking). But still, the fact that Leap Motion is doing such a great job gives hope that Meta will nail it as well.

HoloLens takes an entirely different approach. Microsoft stuck to the long standing tradition of a point-and-click interface. However, instead of moving a mouse around, you move your gaze – more precisely, your head. For selecting, you perform an air tap gesture, which is analogous to a mouse click.

For moving, rotating things, you first select the operation you want to perform, then pinch in the air, and move your hand. As I said in my previous post, this takes some time to get used to, but works fairly reliably once you’ve gone through the ropes.

Meta’s approach is certainly more appealing and natural. However, even if Meta works out the kinks, you will have trouble interacting with virtual objects that are out of your arm’s reach. With HoloLens, you can put a hologram to the other side of the room and just gaze (point) and click (air tap) to perform an action.

So, in order to properly interact with your holograms, Meta needs them to be close to you, within an arm’s reach. With HoloLens, you can fill your room with digital goodies, and keep interacting with them.

Hologram Distance

If you look at something close, such as your nose, your eyes get a bit crossed. If you look at something afar, your eyes look parallel. Similarly, depending on whether you look close or far, muscles change the shape of your eyes to make the light focus exactly on your retina.

Neither HoloLens, not Meta 2 take these effects into count, at least not in a dynamic fashion. To lessen eye strain, HoloLens actually suggest that you place the holograms approximately 2m from the user (between 2-5 meters), and cut the 3D image when you get closer than 0.5 meters. Technically you can display holograms outside of this range, but Microsoft warns you that the discrepancy between the “crossiness” of your eyes and the lenses focused at 2 meters may cause stress and fatigue. My guess is that this is one of the reasons why Microsoft opted for the gaze – and air-tap interaction model.

With Meta, virtual objects that you interact with should be kept inside the 0.5 meter threshold (arm’s length). There is even a demo when you lean inside a holographic shoe. I have no idea how Meta’s lenses are focused, and how much overlap the eyes have for eye crossing – but the demo certainly looks cool.

Understanding the Environment

Environment awareness for mixed reality means that the software and the hardware understands the environment the user is in. It knows that there is a table 2 meters in front of me, which has a height of 1 meter, and such and such dimensions. It understands where the walls are and how the furniture is laid out. It sees a person in front of it.

Environment awareness is important when it comes to placing objects (holograms) in the virtual world. If your virtual pet runs through the sofa or the walls as if it wasn’t there, it ruins the illusion. If you throw a holographic ball, you expect it to bounce off the floor, the walls and the furniture.

This is an area where I could barely find any information on the Meta 2 headset, apart from a few seconds of video showing a ball bouncing off a table.

The situation is different with the HoloLens. Environment awareness is key to the HoloLens experience. When your gaze cursor moves around the room, it travels the walls and the furniture, just as if you were projecting a small laser circle.

When you place a Skype “window” or a video player, it snaps to the walls (if you want it to). When you place a 3D hologram on a table, you don’t have to move it up and down so that it sits precisely on the table. Even games can take advantage of environment scanning, turning your living room into a level in a game – and every room will have different gameplay depending on the layout of the furniture, placement of the walls, and so on.

 

Environment understanding works by scanning the room and keeping this scan continuously updated. HoloLens can store the results of this scan, and even handle large spaces by only loading the area you are in as you walk down a long corridor. It can also adopt to changes in the environment, albeit there are indications that this adopting may be slow. A developer can access this 3d model (mesh) of the scanned environment, and react accordingly. When using the physics engine of a tool such as Unity, it is just a matter of a few mouse clicks to program a hologram collide and bounce off real world objects.

Tracking

One of the things that amazed me (and journalists) when I tried HoloLens was that if I placed a Hologram somewhere, it simply stayed there. No matter how much I moved around or jumped – the hologram stayed right where I put it.

This is an extremely difficult technical problem to get right. Our mind is trained to expect this behavior with real world objects, so any discrepancies will immediately be revealed and the magic will be broken. To keep the illusion, the device has to be extremely precise in following even the slightest movement of your head in any direction. Microsoft uses four “environment understanding” cameras, an Inertial Measurement Unit (IMU), and has even developed a custom chip – the Holographic Processing Unit – to help with this problem (and some others).

To appreciate the quality of tracking HoloLens provides, take a look at the video below. It is recorded on the HoloLens itself, by combining the front camera on the HoloLens with the generated 3D “hologram” overlay. You won’t find a single glitch or jump here. Microsoft is even making an app called “Actiongram” available which can do similar recordings that can record mixed reality videos – something that is pretty difficult and time consuming to do with the standard tools in the movie industry.

 

On the other hand, based on the videos I saw, Meta’s tracking is not yet perfect (but it is close).

 

Road to VR, who – unlike me – had some actual time with the Meta 2 noticed this, too. They said “If you turn your head about the scene with any reasonable speed, you’ll see the AR world become completely de-synced from the real world as the tracking latency simply fails to keep up. Projected AR objects will fly off the table until you stop turning your head, at which point they’ll slide quickly back into position. The whole thing is jarring and means the brain has little time to build the AR object into its map of the real world, breaking immersion in a big way.”

Sound

Sound, especially spatial sound is very important in both VR and MR experiences. Sound can be a subtle indicator that something is happening outside of your field of vision. Microsoft has invested a lot into being able to provide you with the illusion of sound coming from any direction and distance, and it convinced people who tried it. Meta also has a “Four speaker near-ear audio” system, but it hasn’t been mentioned in the videos or reports I’ve seen. When I asked Meta on twitter, they confirmed that it is there to “create an immersive 3D audio experience”.

In any case, adding spatial sound to an object is probably just as simple with Meta as it is with HoloLens. If you’re using Unity, all you have to do is attach a sound to an object (a simple drag-and-drop operation), and the system will take care of all the complicated calculations that will make it sound like an alien robot has just broken through your apartment wall at 7’o clock.

 

Collaboration between Multiple Users

Both Meta and HoloLens has shown examples of multiple users existing and cooperating within the same holographic space. Meta has even shown passing a hologram from one user’s hand to another’s.

At TED, both companies have shown a kind of holographic “video” call, where the other participant could be seen as a 3D hologram. Microsoft has also demonstrated collaboration among builders, engineers, or even scientists studying the Mars surface. Some of these demos had both participants in the same physical space, others were working together remotely.

 

Microsoft is also creating a special version of Skype for HoloLens, which has been piloted on the International Space Station. The astronaut can call experts on the ground, who will see what he sees through the front camera on the HoloLens. Then, the expert can draw arrows pointing out points of interest, or even create small diagrams on the wall to help the HoloLens user solve an issue. The interesting thing here is that the expert doesn’t even need a HoloLens, only a special Skype app that allows him to draw directly in the 3D space of the astronaut.

 

Microsoft does note though that more than 5 HoloLens devices in the same room may cause interference. With devkits limited to 2 orders per developer, and priced at $3,000, this is not going to be a problem for a while.

Price and Availability

During the last few months, Microsoft has been collecting applications for a developer kit. Anticipating a huge demand, developers had to (and still can) apply and convince Microsoft of them being worthy to the privilege of spending a sizable sum – $3,000 – on a developer kit, which will probably be obsolete in a year or less. Still, there is huge interest, and Microsoft is shipping the devices in waves – I’ve even heard of a wave 5, which is pretty scary, since waves can take 1-2 months to completely ship. HoloLens Developer Edition is all set to start shipping on March 31, but only to US and Canada developers.

Meta has also started taking preorders for their developer kit. Meta’s device only costs $949 – plus the expensive, $1000+ gaming computer you need to plug it into. But at least you can use that computer for other things, such as driving your Oculus Rift VR headset or gaming.

The downside is, Meta will not ship until Q3 2016. Being 6 months away from an actual shipping date has its risks. It means that the device or its software is not yet ready, and / or the manufacturing process and logistics still needs work. Solving these issues can take longer than expected. This can lead to further delays, and while I’m hoping it won’t be the case, there is a chance that the Meta 2 devkit will only ship in Q4 or even next year. But once they do ship, I expect them to get a large amount of devices into the hands of developers fast. Oculus has had 250,000 developers, so with Meta not being limited to North America and only costing one third of an arm and a leg, they have a chance of reaching similar numbers.

Summary

The reason I love this tech is that the use cases are pretty much infinite. And even if 50% of those turn out to have feasibility issues due to technology limitations, the rest is still huge. Every aspect of life, every profession can and will be touched by the grandchildren of the devices I talked about.

I’ve already mentioned a lot of use cases for both devices. But I think it is worth to inspect what the companies themselves emphasize.

Meta’s vision is clear. By removing abstractions, such as files, windows, etc., Meta wants to simplify computing and get rid of the complexity that the last 30 years of computer science has built. They are doing this by making the hand and direct manipulation the primary method of interaction. They are also aiming to get rid of the monitors on the workspace – instead of using multiple monitors, you place virtual monitors or even just floating apps all around you, and if you want to access your emails, you just look at where you put the email app. Still, you will be tethered to your desktop for a while, which is something you should keep in mind when deciding whether a certain use case is fit for the Meta 2.

Meta’s field of view is vastly better than what HoloLens has to offer, and by plugging it into a computer, it has access to a powerful workstation and graphics card, and you don’t have to worry about it running out of battery.

On the other hand, the superior tracking, the environment understanding feature, the ability to interact with holograms that are further from you, speech control, and being tetherless are advantages that opens up use cases for HoloLens that are simply not possible with the Meta 2 (as known today).

Having pretty much surrendered the smartphone war to iOS and Android, Microsoft does not want to be left behind on the next big paradigm shift. So, they are firing from all cylinders – aiming not only at productivity, but experimenting with entertainment and games as well. Building on top of the Windows 10 ecosystem also helps a lot. And with their huge amount of resources, they are creating polished experiences that go beyond simple research experiments in all promising areas. However, Meta shouldn’t be discounted from this race – with the current hype, they are sure to secure a next round of investment or will be bought outright soon. And even if they don’t, the enthusiastic community will help take Meta (and HoloLens as well) to new places.

If you thought that at the end of this post, after more than 5,000 words, I would tell you that the Meta or the HoloLens is better – well, you were mistaken. Both are amazing pieces of hardware, filled with genius level ideas and technology, and an insane amount of research. If you want to jump right in as a developer, have the money, and live in the USA: go for HoloLens. If you are intrigued by the Meta 2’s superior visual capabilities, don’t need HoloLens’ untethered freedom and are willing to wait a little more, probably Meta2 that is the device for you.

In any case, what you will get is a taste of the Future.

I am 42 years old. I grew up with home computers and started this adventure with a ZX Spectrum that had a total of 48 KBytes (yes, kilobytes) of RAM, and an 8 bit CPU running at a whopping 3.5 Megahertz. I lived through the rise of the PC, the Internet and the smartphone revolution. All of these were life changing.

By now, I have a pretty good sense of when a similar revolution is approaching. And my spider sense is tingling – the next big thing is right around the corner. It is called Holographic Computing, Augmented Reality, Mixed Reality – even its name is not agreed upon yet. Once again – for the fifth time in my life – technology is on the verge of profoundly changing our lives. And if you are like me, and yearn to live and even form the sci-fi future of your childhood – this is the area to be in.

• HoloLens
• Meta2
• NUI