TransparentHMD: Revealing the HMD User’s Face to Bystanders (2017) [pdf]
medien.ifi.lmu.de
medien.ifi.lmu.de
But otherwise I agree, it makes sense for them to focus on what they can do best with current tech as a stopgap. With current see-through HMD tech, AR ends up incredibly disappointing. (See also: Hololens & Magic Leap's limited FOV)
With a projector, you can't "throw" nothing (aka black). As a result "projected black" is simply lack of projection.
In the case of a translucent or transparent reflection or waveguide surface - which is what the projection reflects off of - "black" is whatever the darkest part of the surface is. In effect whatever else is emitting from the surface that you're looking at will change the depth of "black" you get.
This is why the Hololens and other see through AR devices are always tinted, to set a higher threshold for "black" than the surrounding unaided view.
The are three layers of polarizing material. The two outer layers are at right-angle polarizations to each other and normally would be completely opaque on their own. When power is applied to the liquid crystal, it twists the crystal's polarization to be at a 45° angle to the other two layers, which then permits some of the incident light to pass through.
An optically transparent waveguide display can use an LCD layer to block light coming through the front and then not render graphics on that area of the display. It will be opaque black at that point (though rather fuzzy around the edges, as the LCD won't be in focus).
Magic Leap 2 actually employs this technique. It's... a lot like the rest of the device: a good idea on paper.
If you forgo the projector part and replace the mirror with a transparent LCD, it’s just too close to your eyes and you can’t see anything. If you add a microlens array to the LCD, now the LCD might come to focus but background becomes way too far-focused, and you can’t see anything either.
If we were on an Enterprise-D, I guess I could just ask replicator for a passive illuminated metamaterial light field image combiner with integrated processing than runs on bus power from DisplayPort input, but we are not there yet.
So, for now, our AR HMDs can only brighten pixels against backgrounds.
The blocking all light approach also allows you to hide other potential weaknesses of a device. For example, a lower field of view is much more distracting in a pass-through AR device as you still have your full peripheral vision. VR devices will generally black out the light outside of the FOV making it easier to ignore.
I mean... theoretically you can if you can match photon for photon with the inverse phase. Difficult, I know :)
1. Field of view is limited to existing optics miniaturization
2. Subtractive shading (rendering black) might not be solvable
3. Variable focus objects in the same scene requires projecting n>2 significantly different wavefronts - not solved how to do this with a single vibrating element
For example, close one eye and hold the tip of a pen about an inch in front the other and you'll see that it doesn't actually block any of the world.
Moore's law works great for semiconductors, but Maxwell doesn't negotiate ;)
> …it's a little bit refreshing to know that Apple recognized pass-through HMD AR as too hard and decided to invest in compensatory technology…
I understand the framing as "compensatory technology", but is it possible that what Apple's doing is the simpler and better way to solve the problem? Pass-through AR strikes me as an old-school analog approach, like optical printing for special effects. But a 100% digital vision pipeline seems like it could unlock interesting capabilities like "night vision", new ways of highlighting interesting objects, etc.
The other problem, of course, is that nothing can be truly solidly-colored. Everything has some opacity - which, combined with the FOV issue, is why HoloLens was never marketed as having anything to do with VR.
HOWEVER if someone can get the input -> photon production pipeline to be less than ~10ms, then that does solve a lot of the rendering issues, however it doesn't solve all of the other long term problems that come with that amount of hardware - including weight and complexity.
That said, there's a lot of known-unknowns that need to be solved, for example I don't have a solution for micropiezo resonance issues that I'm sure will crop up.
Currently, NVGs that are fielded by soldiers are already displaying images in a way that's not pass-through (using classic image intensification tubes). Something like the Apple vision headset in a lighter and more durable form factor would allow for eg; fusion imagery (fusing visible, thermal, and night vision).
$4k/unit is nothing when it comes to military hardware. There's also no need for the outward facing display, etc.
If anything, I wouldn't be surprised if Hololens goes in this direction. And the DoD already has contracts around the hololens.
- real NVG costs way above my budget, and all comes with defects. Realistically the tubes in civilian markets are all defective returns.
- even real NVGs can’t work in complete darkness, such as in a closet; moonlight or starlight is needed.
- real NVGs on firearms are often used in conjunction with an IR laser and a flashlight for aiming; advantage is solely that you have to have a goggle to see it, not that you can operate without making any emissions.
- partly due to above points, plain old CMOS cameras with modified 1” Sony sensors for better low light performance is starting to match practical usefulness of a real NVG(it’s Cold War tech so no wonder here). Latency is an issue, but more of “is an issue” and no longer a blocker.
… Vision Pro type of devices replacing NVGs indeed seem like a near future possibility.
They do work in complete darkness! You just need an IR illumination source. If not using a weapon mounted illuminator you can just use an IR flashlight. Thermal doesn't require external illumination but isn't anywhere near as useful for navigation. That said, good IR laser + illuminator weapon mounted systems are a few thousand bucks too.
My point about vision pro type devices is they can take a feed from real NVG tubes and potentially regular cameras and thermal and combine them. It'll be game changing when the tech is ready. It's not a matter of if but when.
I think they're different and not one better than the other. If I wanted to drive with an HMD on, or otherwise be in a situation where it could be deadly to have my sight turned off for even a second or to even have some lag or stutter or other glitch in my eyesight, I'd much rather have a pass-through AR HMD. One's sense of sight seems much more reliable with it by its very nature. You simply don't have those modes of failure with transparent plastic, no matter what's going on in the hardware/software.
Apple can make it possible if they wanted too.
Planes are crazy expensive anyway,so fly-by-wire can be afforded.
Also, it’s true that Airbus sidestick is fully electronic, but there’s a nuance in engine control being in the center on airplanes. Until automated, engine control on airliners was a task of a flight engineer, like it still is on ocean going ships. So fully digitalized engine control is a replacement to the FE, not necessarily an automation of what originally was a pilot’s task. Which means, I think, pushing a vehicle forward was never necessarily the responsibility of a pilot or a driver, though controlling where not to go is.
This is changing rapidly. eg:
https://www.infinitiusa.com/infiniti-news/technology/direct-...
Wearing the quest in pass though mode is kinda cool for a bit, but the lag makes it horrible to use for any more than checking where a wall is.
If they really have made this feel instant that’s a massive deal on its own.
Apple's solution works for >1 people at the same time and doesn't require any external tracking (though it's already doing the external tracking regardless), at the cost of lower resolution and only being correct in one dimension vs two.
https://research.facebook.com/blog/2021/08/display-systems-r...
> There are several established ways to display 3D images. For this research, we used a microlens-array light field display because it’s thin, simple to construct, and based on existing consumer LCD technology. These displays use a tiny grid of lenses that send light from different LCD pixels out in different directions, with the effect that an observer sees a different image when looking at the display from different directions. The perspective of the images shift naturally so that any number of people in the room can look at the light field display and see the correct perspective for their location.
> As with any early stage research prototype, this hardware still carries significant limitations: First, the viewing angle can’t be too severe, and second, the prototype can only show objects in sharp focus that are within a few centimeters of the physical screen surface. Conversations take place face-to-face, which naturally limits reverse passthrough viewing angles. And the wearer’s face is only a few centimeters from the physical screen surface, so the technology works well for this case — and will work even better if VR headsets continue to shrink in size, using methods such as holographic optics.
I'm guessing (?) Apple's approach is similar.
The Wikipedia article might explain it better: https://en.wikipedia.org/wiki/Lenticular_lens
It could work in both dimensions but you're sacrificing even more resolution by doing it that way. For example imagine you have a 1000x1000 pixel display (I just made this resolution up) and you stick a 1D lenticular screen on top with a pitch of 10 pixels. You've effectively split the display into 10 separate 100x1000 displays that are each view from a different angle. You could instead use a 2D lenticular screen and split it up into 100 100x100 displays viewable from a different angle in a 10x10 grid at virtually no extra $ cost. However, you're displaying at 1/10th the resolution just to be able to support perspective-correct views from above or below, which are way less common than from the side.
¹ https://www.laptopmag.com/news/facebooks-bizarre-reverse-pas...
They also add the display that would work with different angles. So it looks like, maybe Apple implemented Meta's research. The timeline could work.
For completeness, there is also another paper "FrontFace" proposing a similar idea that was published around the same time: https://dl.acm.org/doi/10.1145/3098279.3098548
I'm not saying that everything was fixed in stone by 8/2021, but any big hardware features like the front-facing display would take longer than that to develop start-to-finish, so I'm just refuting the possibility that Apple could have started development of a front-facing display on the headset and had it ready on the final product in <2 years.
It's not necessarily that a display itself (or any other individual component really) takes >2 years to develop, but that a tightly integrated cutting-edge system can't have significant hardware features added on <2 years before the final product is demoed to the public.
...but if you're asserting 'I work at Apple, impossible', I'll give it to you.
Generally people believe way too strongly that phones / other hardware /etc. are set 3 years in advance. Note it's well-reported Vision Pro just got to DVT in the last 4-6 weeks.
In my mind it's some combination of:
- New product line (this would be easier in a well established product like iPhone, Mac, etc. or from Quest 2 -> Quest 3). A lot of decisions have to be made much further in advance because you're starting from a clean slate and have to have a final product at the end of similar quality to the iPhones that have been iterated upon for 16 years.
- The Vision Pro is much more constrained in a few key areas that are hugely impacted by the addition of another display: size, energy draw, compute, weight. Much more so than something like a Mac would be. If an additional display wasn't in the budget 2 years ago then you really aren't gonna just find the space for it in all those key areas.
- Custom silicon: Any feature that requires a decent amount of compute and/or IO bandwidth will have to be accounted for when designing the chips. Meta's headsets use off the shelf Qualcomm GPUs and they could in theory bump up a level later in the design process if they need more hardware (not as easily as I described but still possible). Apple simply doesn't have that option.
- By virtue of this being Apple and not Meta/Google/Microsoft/Amazon. I'm not knocking those other companies, but they are differently positioned in the market and are ok releasing more varied and less polished products just to see what sticks. Apple enters later in the game with a product that has had more time to be refined. Google Glass, Oculus, HoloLens, etc. all paved the way for the Vision Pro and it wouldn't really work the other way around in my opinion.
And I am scared of what it means for our society when "eye contact" no longer means a direct connection in person, but an indirect one through 2 cameras and 2 screens.
Obviously this is old hat for Facetime, and all remote collaboration. But in-person too?
Go to an AR web page on your phone and start playing around with 3D objects in your space and you'll notice your phone getting significantly warmer and drawing more power. The Vision Pro is doing this literally all the time.
Also, the camera and sensor work that is tracking your eyes has to happen whether or not there is an outward-facing display.
Apple makes a watch with a display that is always on, and their phones have high resolution OLEDs that can stay on for over 13 hours (iPhone 14 Pro Max 150 nits brightness doing continuous 5G web browsing).
Early reviewers seem to say that the metal construction of the Vision Pro seems to be contributing a lot to its weight. Most other headsets are all plastic.
They’re always evaluating if they can cut a corner.
apple has decided VR zombies hurt their brand & they won't allow it
you see, we wear a noise cancelling headset to pretend to be working, in order to avoid unwanted socialization.
And it seems this is such an important aspect of the product that they're willing to reduce the addressable market from a cost perspective.
This, to me, is what makes this product intriguing. And it makes me think that Apple's real goal is something closer to a pair of glasses, and they just know they can't get there without a long series of iterations.
But that display increases the "creepy factor" by orders of magnitude.
But even if it ends up being a bit creepy, a) I think Apple is well aware of that and b) again I think this highlights how important they think it is to send the message from day 1 that solving for isolation is a top priority and intrinsic to their end-goal.
I was just going by the materials that Apple has released. It's true that I haven't personally seen the device in action in real life. But what Apple has shown certainly triggers a "creepy factor" in me.
Whether or not this is an issue for many people, and whether or not Apple will address it, isn't really relevant. What I've seen right now creeps me out a bit.
Why/how is this not relevant in a broader sense?
Or are you just saying this isn’t relevant to you personally?
A few have hoped you can display something else on it - like cat eyes or something to make it less fucking weird.
Of course in some places if its recording all the time it might be in some weird wire taping situation.
It's not clear that it has shifted yet. It wasn't clear that Google Glass would be rejected until people started wearing them publicly.
With the exterior glass projection you THINK you're making eye contact with them, while both of you are looking at screens through cameras.
dystopian!
A video call will never replace the real thing, but I don’t think I’d say it’s dystopian.
And I don’t find the tech in this headset all that different, the exception being that there isn’t a 2nd set of cameras and screens on the non-headset side of the conversation.
On the other hand, maybe it is dystopian, but if so, I’d argue that dystopia is already here and has been for awhile.
But in a video call, the "distance" the video causes is something that you put up with in exchange for a greater benefit. If I'm talking with someone that has a screen in front of their face showing me their face, that's distance that provides no benefit, so it's a loss without gain. It makes the person seem sketchy.
The video is almost never exactly where the camera is, and if the person is using an external camera or a secondary monitor, the eyeline will never line up.
It's fine! But you never have the illusion that you're talking to the person directly. Which may be is good enough for adults working on professional projects.
But it's not good enough for a parent interacting with a young child.
It's the same sort of creepy I get when someone is wearing a realistic mask.
In the long run, adding a second screen isn't that expensive, and the cameras that capture the video of your eyes already have to be inside the system to perform eye tracking. If smartphone manufacturers can make folding phones with second screens for under $1000 I think that the outward-facing display is not the lowest hanging fruit for cost reduction.
And I am scared of what it means for our society when "eye contact" no longer means a direct connection in person, but an indirect one through 2 cameras and 2 screens.
Obviously this is old hat for Facetime, and all remote collaboration. But in-person too?
U do like the LMU after all I'm in Munich but this though is more obvious than magic.
To the best of my knowledge, this is the first work that proposes putting a photorealistic, perspective corrected face on a VR headset.
"FrontFace" (https://dl.acm.org/doi/10.1145/3098279.3098548) is the first work that proposes putting eyes on a display on VR to "lower the communication barrier".