Occluding virtual objects (real hands in front of virtual sphere) is possible. Occluding real objects (real hands behind virtual sphere) is not.

They're both possible and we'll have more videos very soon to show this. Filming through the glasses is really hard, we've been working on a rig the last few days and will have videos up soon.

Really? To occlude real objects, the glasses would need to have per-pixel adjustable transparency. They look like Epson Moverio glasses[1], and I don't see anything on Epson's site to suggest that they can selectively occlude light, but I'd be delighted to be wrong.

[1] http://www.epson.com/cgi-bin/Store/jsp/Product/Specification...

No, it does not support selective occlusion. Much like Google Glass it's a microprojector against your face, albeit this is two-eyed whereas Google's has one.

I think this is "possible" but unlikely to work well anytime in the near future. There are some really big problems that need to be addressed for it to work properly. To do this convincingly and effectively the glasses would need to incorporate eye tracking. Not only because the relative position of the screens is dependent on the way the glasses are resting on your head but most importantly because the placement of the screens in your view is dependent on the convergence of your eyes. If you're looking at something close (basically anything in the range of what you could manipulate with your hands) the relative position of the screens must be shifted closer together because otherwise you'll see double. It's really something that's very difficult to do and as far as I can see still at least half a decade off.

You're right. I misread your post and didn't realize they demo hands being 100% occluded by virtual objects. Can't believe they're that brazen.

Not understanding the objections. These glasses are a display, right? There's a computer in between ultimately responsible for what the eyes see. With enough clever processing of the scene, why wouldn't you be able to achieve this?

The glasses are not a normal display. Most displays are opaque, and can display pure black by simply not emitting any light. These glasses are transparent, so when they don't emit any light you see whatever's behind the display, not black. Displaying true black on a transparent display requires an extra element which can selectively block incoming light. These glasses don't have such an element, and cannot display black or dark colors unless you happen to be looking at a black object in the real world.

I don't see why it would be impossible; it'd just be pretty hard. What if you had another layer of glass that was like those old LCD calculator screens that have opaque numbers, but can otherwise be transparent? Maybe you could display things in front of those to have full opaqueness. That wouldn't help with variable opacity though.

You're right, an extra LCD layer could definitely do it. I'm just saying that the specific glasses being used here don't have this capability, unless there's some enhancement Meta isn't talking about and isn't showing in their videos.

Virtual objects occluding real objects is in fact nearly impossible. The way you're thinking about it with the extra LCD layer isn't actually a viable solution for this sort of display (or any sort of display my mind can come up with right now). The way glasses such as these work is a lcd screen hidden in the side of the glasses is viewed through a beamsplitter that combines the image of the screen with the real world. The screen appears to be "at infinity" from the viewers perspective. Unfortunately to do occlusion on glasses like this the light would have to be blocked between the source of the light (outside world) and the viewers eyes. The light blocking layer would always appear blurry from the users perspective since it would be so close to the eyes. You would also have problems aligning the light blocking layer with the screen as the apparent position of the screen in the glasses is dependent on the position of the glasses on your head.

Wow, you're totally right! Alignment problems are solvable with accurate positional tracking at least in theory, but I hadn't considered the blurriness problem. That seems like a show-stopper. It might be fixable if the light-blocking element was essentially a holographic display, capable of treating light differently depending on the incident angle, but such technology is going to be out of reach for a long, long time.

There is some nascent technology that allows the eye to converge on two focal planes simultaneously, which looks like it can solve the bluriness problem[1], but I don't get the impression that meta is using this. And it doesn't solve the issue of ensuring parallax alignment between the display screen and the background, which can only really be done if you're tracking the pupil and compensating accordingly...

[1]: http://www.bbc.co.uk/news/technology-17692256