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Comment by rsp1984 | Hacker News Reader

rsp1984

This sounds very cool but from what I understand from the article I guess it would require direct emitter-receiver visibility, i.e. turning around and facing away from the emitter wouldn't work.

Similarly, if you used several emitters to circumvent above problem you'd run into aliasing issues and you'd have to engineer the system such that different emitters can be clearly distinguished from each other.

The low latency is a big deal though. See-through AR is a particularly hard nut in terms of latency because just the slightest bit of it can completely destroy the experience (overlay images lagging behind real world), unlike VR where all the photons come from one source and some latency is tolerable.

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The lighthouses seem to have a 90° sweep. The sensors on the Vive headset (but for some reason not the valve controllers) seem to be in 90° occlusion pits. This means that if the two lighthouses are at opposite corners of a (square) room, for the most part no single sensor will ever pick up both lighthouses at once, no matter where the headset is in the room or how it is oriented.

I think that was the initial strategy, but now they are going with a timing based or modulation based solution, and that's why the controllers, which were developed later, don't have occlusion pits. In this interview with Alan Yates of Valve, he mentions timing, modulation, the role of the LED array, and getting rid of the wire between lighthouses: https://soundcloud.com/hackertrips/alan-yates-of-valve-talks...

(actually from a talk today, it's a 120 degree sweep)

In theory if you could place a second bank of receivers behind your head and had an accurate distance between the two you could simply the problem to just requiring line of sight.

It also sounds like they have a multiple device fix available, the only question being can they devise a way to synchronize two of the devices without requiring the user to do any measurements.

In the article it actually mentions that they already built the system to support it (they are modulating the pulse)

you can stack as many lighthouse units as you want in an arbitrary configuration (which will kill for having huge spaces spanning multiple rooms). i believe the vive headset demo had 2 or 3 units covering 15x15 feet area.

they also have sub millimeter accuracy, to the point that people can pick up physical objects mapped in 3d space, which was how valve demoed picking up the vive controllers whilst you had the helmet on, so you saw the controllers in the 3d space, and they were exactly where they were in meatspace.

> you'd have to engineer the system such that different emitters can be clearly distinguished from each other

It mentions in the article that the light is modulated to permit multiple transmitters, so this seems pretty robust.

couldn't you just set them all at different frequencies?

if not, why not?

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