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[personal profile] mmcirvin
Several years ago Google introduced an extremely cheap and low-end platform for virtual-reality applications called Cardboard, named after a viewer literally made out of a cardboard box with a couple of plastic lenses, into which you put a compatible smartphone. You could assemble one yourself, or buy a pre-made kit for a low price. The idea was that most smartphones already have most of the pieces necessary to do simple VR: they can detect their orientation in space using some combination of mini-gyroscopes, accelerometers and a magnetic compass, and they can display images and render 3D scenes with hardware acceleration. All the Cardboard viewer really did was position a couple of lenses in front of the screen so you could mash it up against your face, and the Cardboard software in various apps would display a couple of appropriately distorted images to each eye so you could look into this virtual space.

Some other companies like Samsung introduced more elaborate variants of the same scheme that added an external controller. 

Today on a whim I bought an even more stripped-down variant of the Cardboard-style viewer, ten-dollar plastic "VR glasses" made by Homido. This thing reminds me even more of a 19th-century stereoscope, which is basically all it is--it dispenses with the box, and just clips directly onto your phone and suspends the lenses in front of the screen. It folds flat in a clever way and comes with a little carrying pouch with a QR code printed on the outside (more on that below). Homido has a player app they want you to download, but it's garbage and there's no point in using it. The device is Cardboard-compatible. It dispenses with any click-generating mechanism; you just click the screen directly with your finger.

So I belatedly got to try out the Google Cardboard platform. It seems half-baked, with inconsistent app support, but clever as far as it goes. You install a Cardboard app on your phone, which establishes systemwide VR settings by scanning the QR code that comes with your viewer. (If you try the following steps and the image is all messed up so your eyes can't fuse it, it means this step probably didn't work. You may have to separately install "Google VR Services" on Android, something it took me a while to figure out.)

Then apps like YouTube and Street View have a "View with Cardboard" icon in the corner of their screen view, which you can use to switch to a view that's compatible with the Cardboard viewer. You can look around the virtual space by moving your head around, and it's cool. Kind of.

The system is limited in a number of ways. Most of these Google apps don't really have a user interface designed to be used through the Cardboard viewer, so you have to periodically stop using it to do a lot of things, which is awkward. There are nice demos that come with the Cardboard app that cleverly leverage Street View and Google Earth capabilities, but the actual Earth app doesn't seem to support Cardboard at all and Street View's support isn't nearly as fancy as the demo's. I haven't, however, done a great deal of exploration of what apps are out there to make better use of this.

Beyond that, the basic concept of smartphone VR has limitations. Lots of 360-degree videos have started showing up on YouTube that are fun to look at with a Cardboard viewer. They don't look quite as good as you'd think, simply because each eye only gets half of the phone screen to look at, so you're sort of peeping at the virtual world through a square window that only has half as many horizontal pixels as a regular landscape view.

What makes it more frustrating is that, in the case of YouTube, there isn't even any real stereopsis to the image: with a recorded video shot with cameras as opposed to a dynamically rendered 3D scene, you can have stereo 3D or a pannable 360-degree view, but not both at the same time, because that would involve continuous changes in parallax. So you're basically looking at 2D video projected onto a virtual spherical screen, and given that, it'd be just as well to somehow present the same pixels to both eyes and get twice as many, for a nice wide field of view. But the optics to do that wouldn't be simple or cheap.

Still, what do you want for ten bucks (plus a smartphone)?

Date: 2017-05-22 01:54 am (UTC)
metahacker: And then a miracle occurs... (You need to be more explicit in step 2, here!)  (miracle)
From: [personal profile] metahacker
It seems like, if you stick three 360-degree (4pi steradian?) cameras in a triangle, a computer should be able to reconstruct a stereo pair of viewpoints in any direction (by reverse mapping the shape of the space and re-projecting the scene onto it). Cameras occluding each other would be a problem, though...

Ironically (?), pannable stereo is much easier for constructed environments than for captured video. And in either case it requires hardware that's up to reconstituting the scene in realtime.

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