HoloLens 2 Review: The Best In Class For AR, But…
The HoloLens 2 is considered the best augmented reality headset in the market. It has been launched in 2019, but because of its very high price and the pandemic that prevented me to travel, in these two years, I have never had the opportunity to try it. But now, thanks to VR Expert, a company specialized in selling and lending AR and VR headsets, I have been able to test this device for a few days and report to you my impressions about it. I’m incredibly happy about this, so finally I’m here writing a review of the HoloLens 2 just for you!
HoloLens 2 Video Review
Here you are my massive video review of the HoloLens 2 (featuring almost 1 hour of content) with many examples of interactions and mixed reality videos! If you prefer videos to walls of texts, this is what you should watch in this article:
Specifications
Let’s start with the specs of the device:
| Display | |
|---|---|
| Optics | See-through holographic lenses (waveguides) |
| Resolution | 2k 3:2 light engines |
| Holographic density | >2.5k radiants (light points per radian) |
| Eye-based rendering | Display optimization for 3D eye position |
| Sensors | |
|---|---|
| Head tracking | |
| Eye tracking | |
| Depth | Azure Kinect sensor |
| IMU | Accelerometer, gyroscope, magnetometer |
| Camera | 8MP stills, 1080p30 video |
| Audio & speech | |
|---|---|
| Microphone array | 5 channels |
| Speakers | Built-in, spatial audio |
| Human understanding | |
|---|---|
| Hand tracking | Two-handed fully articulated model, direct manipulation |
| Eye tracking | Real-time tracking |
| Voice | Command and control on-device, Natural Language with internet connectivity |
| Environment understanding | |
|---|---|
| 6DoF tracking | World-scale positional tracking |
| Spatial mapping | Real-time environment mesh |
| Mixed reality capture | Mixed hologram and physical environment photos and videos |
| Compute & connectivity | |
|---|---|
| SoC | Qualcomm Snapdragon 850 Compute Platform |
| HPU | 2nd generation custom-built holographic processing unit |
| WiFi | 802.11ac 2×2 |
| Bluetooth | 5.0 |
| USB | USB Type-C |
| Fit |
|---|
| Single size |
| Fits over glasses |
| Software |
|---|
| Windows Holographic Operating System |
| Edge |
| Dynamics 365 Remote Assist |
| Dynamics 365 Layout |
| Dynamics 365 Guides |
| 3D Viewer |
| OneDrive for Business |
Unboxing
I have shot the usual video documenting my unboxing experience with the headset.
The video documents my full unboxing experience of the package as it has been sent to me from VR Expert, and it is slightly different from the real unboxing experience with a brand new HoloLens. For instance, in the box I’ve found a cleaning cloth for an Oculus device… and I don’t think it actually comes with a Microsoft HoloLens! Anyway, the unboxing above is very interesting to evaluate how VR Expert sends its devices… I’ll come to this in a while.
If you want to see an original unboxing experience, you can watch for instance the one of my friend Sebastian Ang
When you buy the HoloLens 2, inside the box you will find the following items:
- HoloLens 2 device
- Carrying case
- Overhead strap
- Microfiber cloth
- Charger
- USB-C cable
I think the packaging is very nice. I especially loved the fact that together with the device, you are already provided with a very elegant black carrying case, where the headset and its accessories fit very well. It is a very simple packaging because basically you have only the headset inside, but it has been done in a very good way. It didn’t put me in awe, but it has my seal of approval.
VR Expert packaging
As I’ve told you above, this review is made in collaboration with VR Expert, a company that sells and lends XR headsets. They sent me the HoloLens 2 for free to keep for some days so that I could review both the glasses and their service. And I have to say that their packaging is pretty good: the device arrived me in a pretty big plastic box, that let the device travel without the risk of being damaged. Inside, there was the box of HoloLens 2 protected by some cardboard, so that to protect it even further. What surprised me is that the box contained everything I needed to get started with the device, and also to return it back.
I wanted to start using immediately the headset, and I was happy of finding it completely charged, with next to it a short quickstart guide that showed me how to interact with the headset and configure it for my first usage. Then I also found everything I needed to return it back: the seals to close the box, and the transportation document to attach to the box to return the device back without having to worry to call a shipping company. I received the headset and I hadn’t to worry about anything: everything had already been handled for me.
I’ve found the packaging incredibly handy and well-made: it’s probably the best way a company has ever sent me an XR headset to test in all these years. Kudos to VR Expert for this.
If you want to borrow a HoloLens 2 for some days or you want to buy it from VR Expert as well, you can check out this link: https://vr-expert.com/ar-headsets/buy-microsoft-hololens-2/
Design
HoloLens 2 is a very elegant device, made with high-quality materials. It is smaller and lighter than it seems in videos, and when you see it, you have immediately the impression that it is a premium product. The choice of the black color and the fabric finishes make it look like a professional tool, so it is perfect to use in enterprise settings.
Let’s evaluate together how the device is made.
Looking it from the front, you can see the six tracking cameras: the 4 lateral one are b/w used for positional tracking, the central one is an RGB one, and below the RGB one there is the depth camera (something like a mini-Kinect). From here, you can also see the protective glass and the lenses.
On the left side, you can see the headband that goes all around your head to fit the headset, plus the top strap that helps in distributing the weight. On the headset, barely visible in the photo, there are two buttons to increase/decrease the brightness of the holograms.
From the right, the headset is very similar to what you can see from the left, with the only difference that the two buttons here are to turn up/down the volume.
On the back, you can find the big battery of the device, and the knob to close the headband around your head.
From the top, you can admire the whole fitting mechanism, including the cushion that there is on the back and that touches your nape.
Looking at the headset from the bottom, you can see the two integrated speakers (they are those two little long holes in the headband)
Visuals
The visuals of HoloLens 2 have been very disappointing to me. For sure you have read all those online reports of people seeing “rainbows” when looking through the headset… well, I had those rainbows on my device too… and not only that!
On my device, I have found all the possible problems I could imagine. The “rainbow vision”, that is color inconsistency all around my field of view was very prominent, and noticeable especially when I had a white virtual image in front of me (like a Window of the OS). I could clearly see bands of different colors all across my view, like if various rainbows were super-imposed to the virtual elements. This was less noticeable on colored elements, where I could only spot some inconsistency (like if it were mura), but on white, it was really disturbing.
Besides that, I also noticed the “screen door effect” for the first time on an AR headset. I could clearly see the “pixels” of the AR display, and I could also spot that the pixel density was bigger in the center and became less detailed in the periphery of the vision, where the screen door effect was even more noticeable. Because of this, the edges of some elements also looked blurred. There were also glares when I had bright elements in front of me, and what seemed chromatic aberrations: I could see some images decomposing in their main colors. To make everything worse, the internal part of the lens was reflective, so if I had a light source behind me (e.g. a light bulb), I could clearly see it reflected onto the lens, for a very annoying effect. As a cherry on top of the cake, sometimes I saw some weird glitches appearing here and there in my field of view (like static noise appearing for a fraction of seconds)
The collection of visual issues I’ve found in this device, which is priced $3500, was very disappointing. I’ve heard that there are some different versions of HoloLens 2 out there, with some of them having very prominent rainbows, and others with slightly better visuals. Mine was one of the bad types I guess, and I came out hugely disappointed but what I saw with regard to what I expected.
Talking about the positive features of the display, I can assure you that the colors are very bright, and the “holograms” yet semitransparent, usually look pretty good. The bright colors are what make you forget about all the problems depicted above, and let you enjoy the augmented elements that you have in front of you. Keeping using the device, you usually get used to the screen door effect, the rainbows, and all the rest, and you just enjoy the great AR offered by HoloLens, in the same way you get used to the limited FOV when you use a VR headset.
Talking about the FOV, I can tell you that it is much better than the one of the other AR headsets that I’ve tried (with the exception of RealMax), but it is still not enough for satisfying AR. It has a 3:2 ratio for a total of 52° diagonal, and this is good if you have to examine objects that are some meters in front of you. But as soon as you get close to them, the magic breaks, because you can clearly see the limit of your viewing windows. This is especially true if you get close to big elements like a car or a big fire. Microsoft has increased especially the vertical field of view in this device, and I can tell you that they made a very good job in this, because more vertical FOV is important for immersion. Anyway, 52° diagonal is still little.
The pixel density being inferior in the periphery than in the center of the vision comes in handy for the FOV management: it creates an effect for which on the horizontal FOV you don’t see an abrupt interruption of your vision, but you see the visuals fading away, with a gradient effect that makes the FOV window less noticeable. You don’t have this nice stuff on the vertical side, though. The FOV is big more or less like the lens that you have in front of you, and this means that as it happens in other similar devices (e.g. Magic Leap One), your brain kind of accept that you see augmentations only through the lens of the glasses and not in the peripheral vision, and so the limited FOV becomes more acceptable. So, Microsoft has made whatever it could to make the limited FOV more acceptable and we have to appreciate that.
The device is meant to be used indoor. I tried using it outdoor on a cloudy day and it was usable, but the augmentations looked very transparent and with washed-out colors. I guess that on a sunny day, it becomes absolutely unusable.
I was pretty disappointed that the “holograms” do not adapt their brightness to the lighting of the environment you are in: with systems like ARKit this is already possible, while here the system doesn’t even adjust the overall brightness depending on the light of your room. The first time I turned it on, it was evening, and the super-bright white OS windows were too much for my eyes. But at least I could adjust brightness manually using the brightness controls that are on the headset.
Someone complained about the lenses being slightly dark so that to give more visibility to the holograms. It is true, the lenses remove a bit of brightness from the sight of the real world that is around you, but I have found the effect absolutely acceptable. It is not dramatic as some people say, it is just that things are a bit darker. And when you are looking someone else that is using the headset, you can still look at them in their eyes (even if you see them darkened). One of the pro sides of AR is indeed the one that it feels less isolating, and people in AR and people outside AR can still have eye contact. But HoloLens ruins all of this when in some conditions (depending on what the AR screen is displaying and the angle from which you are looking at the other person), you see a psychedelic colored barrier in front of the eyes of the person that is using the HoloLens, and it looks a bit cyberpunk and a bit creepy. This is absolutely not how people in AR would like to look.
I just want to close this chapter on visuals telling you that in the end, using the device is not that terrible as it may seem from the above paragraphs, as long as you decide not to focus on the problems it has and you don’t have white windows in front of you. Sooner or later you get used to all the problems it has, and you just enjoy AR, like in VR we all get used to limited FOV and screen door effect. But the moment that you stare at something and pay attention to it, you may start noticing all the limits of its display system.
Audio
Hololens 2 features integrated audio via two speakers that are installed in the lower part of the headband and that go above the ears of the user. The audio is loud and clear and for my average ear, it is very good. It is not mind-blowing like the ones of the Valve Index or the Vive Focus 3, but it is absolutely good. You can also turn up and down the volume using two buttons that are installed on the device.
What surprised me is that HoloLens doesn’t feature the classical 3.5mm jack to use your custom headphones and that is present in almost all VR headsets on the market. Probably the designers haven’t found it comfortable to wear this headset together with custom isolating headphones, and so haven’t given this possibility to the users.
The microphone works also very well: I recorded many mixed reality videos with HoloLens, and my voice was always clear to hear, and the recording was also without noise or other artifacts.
Comfort
Comfort is one of those characteristics where the HoloLens 2 truly proves to be amazing. The headset is very easy to fit into your head by just adjusting the top headband and then closing the rear knob to close it around your head.
It is incredibly balanced thanks to the fact that the battery is on the rear and the display on the front. The weight distribution has been carefully studied, and so the device doesn’t touch the nose of the user, but it rests on his/her forehead. The front and rear cushions also contribute to the overall comfort. No one of the cushions is super soft, but they are soft enough to make them comfortable and also resistant to multiple hours of usage (something very important in enterprise settings). The rear cushion is also in a material that is very easy to clean (something like leatherette), while the front one is made in fabric/sponge, so it looks less designed for hygiene.
The headset is smaller and lighter than I thought, and this contributes to the overall comfort. I felt no fatigue in wearing it, even if I kept it on my head for more than one hour. With the Quest 2, this is absolutely impossible. Its only problem is that the forehead region the headset rests on tends to sweat, also because the device can become a big warm after prolonged usage (but it never becomes hot). And when you remove it, you can see some signs on your head.
I tried to make also other people wear the device and no one of them complained about its comfort. One of them even wore glasses, and they fit perfectly into the headset. Everyone has also appreciated the fact that you can flip up the display in case you want to do something that doesn’t require AR. It’s an amazing feature: you just take the display, you rotate it, and you can interact with people in the real world; then you rotate it down and you are in AR again. Super handy.
Positional Tracking
Positional tracking is a category where the HoloLens 2 is the absolute king. There’s to my knowledge no other AR headset that can show the augmentations in a way that is this stable. With all the other devices, when you rotate your head, when you move inside your room, the augmentations move a lot, while with HoloLens, they stay fixed in place, as if they were real objects in the real world. And this is what gives you the real magic, what makes you forget all the issues of the display, and makes you understand how AR is truly powerful.
The headset tracks its position in a very fast and accurate way and when you put a “hologram” in the world, it stays there, exactly in that position, no matter how you move your head. You can wander around the room and see it staying there, like if it was real. This is a so powerful effect, that I’ve never tried with other devices: holograms are so stable that are like if they are part of your room. You can really understand how our mixed reality future will be with these glasses.
If you look closely, sometimes the virtual elements slightly wobble, and when you go distant from them, they can have some error of measurement and enter a bit into a wall for instance. It is still not 100% perfect, but I would say we are 90% there, while with other headsets we are at like 60%. Pair this stability with the very bright colors, and you understand why people think that this device is the best AR headset on the market.
The Achille’s heel of positional tracking is the light: if the room is completely dark, it doesn’t work anymore.
Hands Tracking
HoloLens 2 has no controllers, but it lets you interact with the mixed reality elements through hand tracking, eye tracking, and voice commands. This is a very innovative decision, and I was pretty skeptical about it, but after I have tried it, I can say that it works.
The secret to making it usable is the monstrous hand tracking algorithm. Microsoft has studied hand tracking for many years, and I remember some research on it already done with the Kinect v2. This big expertise is clearly visible in how hand tracking works incredibly well on HoloLens 2. At this moment you are probably wondering if it is better or worse than the one of the Quest 2. Well, it is not only better… it is THAT better. Microsoft is really showing Facebook who is the king of computer vision.
With HoloLens hands tracking, you can take your hands and interwave the fingers of one hand with the ones of the other hand, and it keeps tracking. You can turn off the lights, and it keeps working. You can move your hands all around your field of view, and they are always tracked. And the precision is also very good… good enough that you can use your hands as the main input means of the headset. It’s impressive.
Don’t expect it to track exactly all your five fingers all the time, though. It is still not perfect, and there are some glitches sometimes. Plus it has a noticeable lag with which it follows the real hand. But it is already very good. Also, the field of view of hands tracking is bigger than your visual FOV, and for most hand poses it work, but it is not as wide as the one of the controllers of the Quest, for instance. If your hands are above the headset, they are not tracked, if they are too much at the left or right of the headset, they are not tracked.
And here comes my personal critic of the use of hand tracking as the main input means. The tracking technology, as I’ve said, is impressive, but sometimes I would have preferred to have controllers anyway. The good of hands tracking is that you put your HMD on and you’re done, you don’t have to also wear controllers, and this is also great for enterprise applications, where the employees usually must use their hands to perform their jobs (e.g. in maintenance), and they wouldn’t find comfortable to have to put on and off controllers continuously. But the bad of hand tracking is that you don’t have real haptic feedback of what you’re doing, and also the FOV is quite limited. Plus it is also quite tiresome.
On the Quest, I can lay on a chair, and put my hands with the controllers lazily on my legs, and by just moving my wrist interacting with the VR elements. If I click a trigger, I know I have given the system my input, because I mechanically pressed it. But with hand tracking, since the FOV is limited, I have to actively move my whole arms to interact with the AR elements I have in front of me, and this is tiresome in the long run. Plus when I perform the “air-tap” gesture (that is the click with the thumb and the index finger), I don’t understand immediately if it has been taken or not. I don’t even understand if the system is tracking my hand, if it is outside my field of view. Add to this the fact that sometimes the hand tracking is glitchy, and that the pointer on the index finger through which you interact with UI elements by touching them is usually slightly offset from its real location, and you understand why hands tracking can sometimes be frustrating. Sometimes I tried to press buttons with my real index tip, but they didn’t work, and then I realized that the actual cursor was 1cm behind its real location, and so I couldn’t use my hand proprioception to interact with the UI, but I had to constantly look at where the virtual cursor was.
Hand tracking technology is amazing, but to use hands as the only input mechanism of a headset, it still needs to improve it a bit.
Eye Tracking
Eye-tracking on HoloLens 2 works more or less like on all the other devices where I tried it. It is usable, it works, but it is not perfect. And especially, it requires an initial calibration for every user, or it won’t be reliable at all.
Eye tracking can be very useful for enterprise applications: for instance, during training sessions, analyzing what the user is observing can be fundamental to understand if he’s paying attention to the right things or not. That’s why it is fundamental that eye tracking has been added to this enterprise device. And it is also great for accessibility: people that can’t use their hands could use eye tracking and voice to provide input to the device.
In all demos that I’ve tried, though, I have rarely seen it used in a convincing way. Some samples let you use eye tracking to select objects or to interact with objects (e.g. to zoom a map), but this is completely unnatural. We use our eyes to look around, to analyze, to explore, never to interact. And when an application forces you to use eyes as an input mechanism, it always feels bad for some reason (unless it is for accessibility, of course). Remember that our eyes are also meant to wander around to explore the environment around us with very fast movements and if you use them as an input mechanism, you risk the “Mida’s Touch” problem. That is that whatever you look at with your eyes, even without thinking, just because your eyes are exploring around, gets input commands. For example, in the MRTK demo that used my eyes to scroll over a map, it was weird to see the map moving when I was just looking around to see things around me and randomly looking at the map.
And do you remember that demo all magazines talked about, that you read a text and when you arrive at the bottom of it, the text scrolls automatically?
In this case, the foundation of it is correct: the program doesn’t use the eyes as active input, but just analyzes their movements, and so scrolls the texts automatically when it thinks that I need to scroll it. But first of all, I’ve never requested it, so this seems strange to me. Then, it’s very hard to read the text while it is scrolling, considering also that the provided scrolling speed is not uniform. Needless to say, it doesn’t work. Nice idea, mediocre execution.
The only cases where eye tracking is well implemented is when it is used to understand the intentions of the user, for instance, paired with voice commands. With your eyes you look at something and then you give a command to it by voice: in this case the voice trigger makes sure that eyes are not used as the main input means and the Mida’s touch problem is solved.
Voice controls
It is possible to give commands to HoloLens using your voice. This comes in handy especially when paired with eye tracking. For instance, you can look at a window and say “close” to close it. The system understands what window you are interested in thanks to your eyes, and then closes it because you said that with your voice.
Commands detection works much better than HoloLens 1, but I still think it is not usable for commands that are not just a single word, if you have to speak English and you’re not a native English speaker. I’ve tried saying sentences like “Zoom in” or “Come here” when testing the demos, and I have come out disappointed by the voice engine not being able to understand those sentences said with my sexy Italian accent. I’ve noticed that performances are much better with simple words like “Select” or “Close”. More complex sentences usually require me to repeat them two or three times before they are correctly interpreted. I guess that native speakers don’t have the same problems, though.
I’m not a huge fan of voice commands, because they are very annoying for the people around you, especially if the engine doesn’t understand what you are saying and so you have to repeat “Zoom in” in a loud voice ten times while all around you look at you like an idiot. But it can be very valuable for workers that are performing something with their hand, and that can so command their device without having to stop what they are doing.
Environment understanding and reconstruction
HoloLens 2 can scan the environment around you to provide you better augmentations. It produces a mesh of your surroundings that is constantly updated, and can be used for instance to occlude the virtual elements that are behind real objects, or to make the physics of the virtual objects work realistically with the real ones. And when these things work, they feel like black magic: you drop a virtual dice, and it bounces on a real surface and then maybe falls under your desk, and you can’t see it anymore because the real desk occludes it. When these moments happen, your brain goes in awe, because it is like virtual objects are part of your real world.
But rarely these real-virtual interactions are this perfect. The mesh reconstruction on HoloLens 2 is more accurate than in HoloLens 1 and it also works faster. But the resulting mesh has still some holes, especially when there are monochrome surfaces (e.g. the corner between a wall and the ceiling). Its resolution looks like made of quads of 10-15cm for each side, and it is not enough to reconstruct exactly the shape of all objects around you, but only to grasp their generic shape. Sometimes the mesh is slightly offset with regard to the real object (some centimeters), and this is enough to break the magic in the physics interactions. Sometimes the mesh fails at reconstructing the shape of an object: the desktop PC in my office was detected with the shape of a hill, for instance.
There’s still a long road to go to have perfect environment reconstruction, but the one of HoloLens 2 is already usable for a good number of tasks. The system is also able to detect the planar surfaces in your room (e.g. tables, walls, floor, etc…) and this can be used in some applications. Microsoft has been the first to introduce with Hololens 1 the persistence of virtual elements, and HoloLens 2 keeps this tradition: the system remembers in what rooms you have been in, and as soon as you enter again in a room, it shows you the holograms that you have left there in your last session. When I opened Microsoft Mesh to shoot a part of the Youtube video review, it showed me the drawings that had been left in my room the night before, with a completely different illumination. Environment detection works incredibly well. And it can be used also for local multiplayer between two users donning a HoloLens 2.
You can of course pair all this with Microsoft Azure, and use Microsoft Cognitive Services to apply more complex environment understanding algorithms on top of what is offered by default. It is so possible to use Azure to detect objects in your environment and use this feature for instance in training sessions with real tools.
Computational power
The system relies on a Qualcomm Snapdragon 850 chipset, with a separate unit, the HPU, that is dedicated to performing all tracking tasks, offloading them from the CPU and the GPU of the glasses, that can so give their full power to the running applications. The 850 chipset is a bit more performant than the 865 of the Quest 2, even if it has been released one year before. But the most important thing is that, as I’ve said before, the HPU frees it from all the tracking computations, so it can give more computational power to the XR experiences.
I have not had the time to perform an extensive test on the performances, but I can say that all the applications that I tried run smoothly to me. On HoloLens 1, whatever Unity application I run had framerate problems, while here all Unity applications worked like a charm. The system worked well also while recording and streaming the application I was playing, even if in that case I could see a slight drop of the framerate.
From my short test, the computational power is enough to let you play simple XR experiences, but of course, you have still to produce optimized content. You’re not working on a desktop PC. But even here Azure can come handy: Microsoft offers cloud rendering as part of its offerings, and you could use it to run on HoloLens 2 an experience that is too heavy to render locally.
Battery
Microsoft claims 2-3 hours of battery life when the device is in use, and around 2 weeks when it is in standby mode. From my tests, 2-3 hours is pretty accurate as the duration of AR session you can hope to have. In my opinion, it is not bad, even if probably 4 hours would have been better considering that in enterprise settings you may need to use the device for many hours. The device goes in standby automatically if you put it on the desk and don’t use it for a while: it helps you with battery management.
Menu UI
The OS offered by HoloLens 2 is Windows Holographic, which is a version of Windows 10 that runs in a 3D world instead of a 2D display. To trigger the start menu, you can use your left hand to touch the wrist of your right hand, where you can see the Windows icon, or alternatively, look at the Windows Icon on your right wrist, and make the thumb touch the index finger of that hand. The “Start Menu” is a floating window that follows your head and that lets you run the various applications of the device or select some shortcuts for some common operations (e.g. to shoot a photo).
From the start menu, you can select what application to start, and they can be of two types: non-immersive or immersive 3D ones. Non-immersive apps are mostly floating 2D Windows (e.g. Store, Settings) or 2D Windows that can spawn 3D elements (e.g. 3D Viewer). They are usually displayed as the classical Windows 10 windows, but instead of being on a 2D display, they float around your room. You can decide to let them follow your head, or you can put them in a predefined position of your environment (e.g. on a wall). These applications can co-exist with other applications of the same kind, because they just occupy defined parts of the environment. That is, if an app is just a floating Window, you can have it running in your room together with other floating windows, exactly like on your computer you can run Firefox together with Microsoft Word. Non-immersive apps allow you to perform multitasking.
Immersive apps are the classical AR applications that we always have in mind: they show 3D elements and they can occupy all the 3D space around you. For instance, Microsoft Mesh, an application that lets you draw elements in your space and meet other people in AR, is an immersive app. Immersive apps need the exclusivity of the space around you, so when you launch one, all the other applications get paused and removed from your view. This is obvious: like you can’t play two VR games at the same time, you can’t run two AR applications together, unless you want the 3D elements of one to mix with the elements of the other one.
Applications are downloaded from the Microsoft Store, which is a 2D application on this device, and features only experiences that are compatible with HoloLens 2. Once you have installed an application, you find it in the Start Menu, and from there you can start it. When you start it, you can also position the 3D icon of the application in the space around you, like if it was the minimized version of your app on your taskbar: in case of non-immersive apps, this icon is just the window, in case of immersive apps, it is a 3D model. All these 3D icons and windows that you put in your space represent your workspace and stay there unless you close them. Even if you turn off the device, when you turn it on again, as soon as the operating system recognizes your room, it puts again there the icons and the windows where you left them. This works incredibly well and feels like magic.
Most of the interactions with the OS are with the hands: you can use the hands with distant objects through ray-casting (in this case you see a ray coming out from your hands) and clicking via air-tap (thumb and index touching) or use them with near objects via direct touch: you use your index fingertip to directly touch the UI elements to click on them. As I’ve said before, hand interaction works well, but it has its own drawbacks: it is tiresome in the long run, and sometimes the hand is in a slightly different position than its virtual cursor, and this can be a bit frustrating. But most of the time, it is ok, and it’s fun to use the hands to move windows, to enlarge objects, to rotate stuff with gestures that look very natural.
You can also interact with the elements via voice: for instance, you can close a window by looking at it and saying “Close”. Usually, the system takes some seconds to understand your voice commands.
To compensate for the lack of haptics, the UX of the various windows usually features many visual and audio cues to let you understand when you are interacting with an element. Anyway, I personally think that Microsoft could have done a better job with that: the virtual keyboard still feels a bit weird to use without touch, and it’s not always easy to select a button with your fingers if it is close to other buttons. As I’ve said before, there have been times when I really had preferred to have controllers for more accurate input. And other times, I’ve found that the UI could have been made better, with better cues to make me understand with what element I was interacting with: I have seen better hands UI in an application like Hand Physics Lab than in HoloLens.
I’ve also found many glitches in the OS: sometimes the hand input didn’t work to interact with the Windows and I had to use the voice, or vice versa. Other times the applications crashed on startup, and I had to launch them again. AR still feels experimental and not ready for prime time.
Demos
HoloLens 2 is an enterprise device, so on the Microsoft Store, you don’t find many applications for it, because you are supposed to develop the experiences your company needs yourself. Of the experiences that you can find on the Store, a good percentage of them requires a login because they are intended only for already registered customers that are paying a monthly fee. The Store is very focused on enterprise, and instead of having gaming categories like on the Oculus Store, here you have categories like “Architecture”, “Education”, “Maintenance” and such.
The experiences that you can try for free are usually tech demos or free trials of premium services. I have tried all the experiences by Microsoft that teach you how to interact with the device using eyes, hands, and voice. The hummingbird that flies and then sits on your hand is a demo that everyone likes.
I’ve tried the 3D Viewer, which lets you put animated 3D elements all around your room to decorate it. I’ve played with some minigames, like a 3D Tetris. I’ve also tried Figmin XR, which makes you create 3D interactive scenes without the need for you to know how to code: it looks very cool. HoloAnatomy lets you understand the future of mixed reality education: you can put a skeleton in your room, and then change its visualization, seeing it with the muscles, the organs, etc…. it is just a demo but it already makes people understand immediately why mixed reality can be important for education: thanks to MR, everyone can have an anatomy lab at home.
An application I suggest everyone install and test is the MRTK Examples Hub. It is just a tech demo that shows you the features of the MRTK SDK for HoloLens, but it’s very cool because it lets you test hands interactions, voice control, and eye-tracking, and a combination of the three. It is a collection of development samples, and if you are a developer, it is a goldmine to let you understand what you can do with this device.
There is also a preview of Microsoft Mesh that you can try for free. I have tried it alone unluckily (I had just one HoloLens), but it was already nice because it let me put 2D objects and 3D objects into my space, zoom, rotate, and move them with my hands in a natural way, and also draw in free form with my fingers. If there were another person with me in Mesh, we could work together on all these elements. The space it created was persistent, and when I launched Mesh, I always find in the space all the graphical elements that I left in that exact room in my last session. It felt like magic. And it also felt like magic seeing all the objects I created sitting there in the room, fixed in space, as if they were part of my real environment. It is still a beta and it has its share of issues, too: for instance, the cursor being in the middle of the thumb and the index was not always usable.
There’s enough content to let you play a maximum of one day with the device, and after that time, there’s not much to do. The games on the Store are just a few and of questionable quality. But it is an enterprise device, so this situation is normal.
What it lacks, IMHO, is a WOW demo, something that you can make other people try to put them in awe so that they immediately grasp the huge potential of AR. This would help in selling the HoloLens 2 much better.
Device Portal
One of the best features of the HoloLens 2 is the Device Portal, a feature that Microsoft carries on from the first HoloLens. Basically, the HoloLens has a web service, and if you connect with a browser to its IP from a PC that is in the same local network, you can access a portal through which you can control the device. On the Device Portal you can for instance:
- Install and uninstall applications on the device
- Check the running tasks (basically have a Task Manager of the headset)
- Check the current performances (% of CPU used, % of memory used, etc…)
- Record videos and photos from the headset and transfer them to your PC
- Watch a live preview of what the user in the headset is seeing, so that you can guide him/her (this is amazing for demos to customers)
These are just a little subset of the available features. The portal is very powerful and it is an invaluable tool for everyone that has to use the device.
SDK
I had not much time to play with this device in Unity, so sorry, but you won’t have a tutorial on how to create The Unity Cube for HoloLens 2. But I have good experience developing for HoloLens 1 and I’ve also already explored MRTK, so I can tell you a high-level opinion on how it is developing in Unity for this headset.
Developing for HoloLens 2 is different from developing for VR headsets, and also for other AR devices. HoloLens is a Windows 10 machine that runs Universal Windows Apps (UWP), and it is a completely different beast than Android, which is the usual operating system of XR headsets. UWP lets you use just a subset of the C# libraries, and you have a series of restrictions that remind a lot of the Android environment (e.g. you can access only the features for which you requested permission). Personally, I have always found it very annoying developing for UWP.
You can’t use controllers, but just hand tracking, and this is a paradigm that makes things a bit more complicated if you are used to developing for a VR headset. And learning how to design the UX of your experience by using hands, voice and eyes is a work that can be new for many of you.
Luckily for us developers, the SDK for developing for HoloLens 2 is MRTK who is nothing short of fantastic. This SDK contains everything: facilities to configure your project for HoloLens developments; tools to let you build and test the applications directly onto the device; a complete set of all the building blocks that you may need for your app; a set of samples you can take inspiration for. The building blocks that MRTK provides are impressive: you have basically all the UI elements you may need, plus all prefabs that you can just drag and drop to add voice or eye interactions to your application. And all of this is extensively documented on GitHub. MRTK is fully open source, and there is a big community working on it every day. It’s probably the best SDK among the ones of the XR headsets on the market. And it doesn’t work only with HoloLens, but it is crossplatform with many other AR and VR headsets. It is really impressive.
Another amazing thing about developing for HoloLens is the emulator: if you have Windows 10 Pro, you can install a HoloLens emulator that lets you try your application without having to deploy it to your real device, for much faster development times. And there is also a way to stream the application to HoloLens by just hitting Play inside Unity, another feature that helps in testing your experiences faster.
Starting to develop for HoloLens requires some days to get used to its completely different development environment, but as soon as you learn with the samples and the documentation, you can go on pretty easily thanks to the many features of MRTK.
Price
HoloLens 2 can be bought on the Microsoft website or through selected resellers (like VR Expert, or Hevolus in Italy) for $3500. There are two versions, one dedicated to enterprise, and the other to developers, but they have the same price. There is also an industrial version, with added certifications, that costs around $5000.
There are various purchasing options and also the possibility of paying it with monthly payments of just $99: I invite you to check the dedicated page on Microsoft Store to find the option that suits you the most.
The price is clearly artificially high: the headset per se could be cheaper, but since Microsoft wants to target big industrial players, it is offering this headset at a very high price, hoping to earn money by selling a limited number of headsets with a high margin. It’s the classic business headset sold at a high price because it includes many enterprise-oriented services. In my opinion, it is too expensive, even for the good value it gives, but its price has been calculated with some careful business planning, and I’m not going to argue with Microsoft’s business reasonings.
Final Considerations
HoloLens 2 is considered the best AR headset out there, and after my short time with it, I confirm that it actually is. But I also have to say that it is worse than I expected, and I haven’t come out completely satisfied by it.
When a device is priced $3500, I have very high expectations, and when I see things like the display that is so full of issues, I can’t be happy about it. Turning on the headset and see the “rainbow vision” as the first thing, has been a huge turn down for me. I also expected something more from the voice detection system, and also from the UI/UX, that in my opinion could be better and make hand interaction more effective. The bugs in the OS (e.g. applications not starting on the first try) were also quite annoying for a headset this expensive. Also, not having a demo that can give WOW effect is an issue for this device, which is so harder to sell if you want to show it to your bosses to ask for funds for an AR project.
But HoloLens 2 shines for what concerns comfort, and the bright colors of the virtual elements paired with a best-in-class positional tracking give you the wonder of a great integration between real and virtual elements that no other headset can give you. Not having controllers makes you feel freer, and all the various interaction modes (via hands, voice, and eyes) are perfect for workers that have to operate in the industrial field with their hands. If you are a developer, you can appreciate all the facilities offered by MRTK and create apps more easily. And this device integrates very well with Microsoft Azure and all its related services (remote rendering, artificial intelligence, etc…) that make it incredibly powerful. These pro features are what make you forgive all the cons described above and make you think that this is truly the best AR headset out there.
But the road towards high-quality consumer-grade AR is still long.
I hope you liked this review, and if it has been the case, please subscribe to my newsletter to not miss my next article about AR and VR! And if you have some questions or comments about the Hololens 2, feel free to write them in the comments here below!
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