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How Does Constellation Work?

Anonymous
Not applicable
Hey,

In an effort to direct my VR curiosity to more productive outlets, I've been reading up on how all of this technology works. I've been able to find lots of information on the lighthouse / vive tracking system and read some fascinating stuff about ATW on the rift, but haven't been able to find details about how constellation actually works. I know LEDs on the headset are detected by the sensor in IR, but I'm looking for more detail than that. Does anyone know a good resource that explains it? 

Thanks!
5 REPLIES 5

shadowfrogger
Heroic Explorer
There are bits and pieces all over the net but I don't think I've seen a indepth review yet. I'll tell you the short notes, in addition to being tracked, each ir light blinks in sequence(really fast) which is synced to the pc via USB. So, it knows exactly which ir light on the headset it's looking at.
It then turns all the ir lights down to points, then creates a 3d wire frame model. Because it already knows the exact distance from the points(pre-coded), it can get the correct angles from point to point, the lights are set out that from any angle it has enough reference points to give a 3d model. It also mixes information with the on board rotation sensors which work at 1000hrtz, there is also prediction of rotation/postion done that is mixed in. It's a very very slight prediction, e.g if a car is going 80km and decreasing in speed, then in the next millisecond, it's must be within 78km-79km.
I think there was a blog article very early on this site. Hope this helps a bit
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Dreamwriter
Rising Star
On a low level, they work like the Wii Remote's pointer-device - the camera sees the light circles, and measures the size of them. Then when the light circles get bigger, it knows that light is moving closer to the camera, when they get smaller, it knows that light is moving away from the camera. And of course it tracks how they move as well, seeing their translation and rotation.

cybereality
Grand Champion
AMD Ryzen 7 1800X | MSI X370 Titanium | G.Skill 16GB DDR4 3200 | EVGA SuperNOVA 1000 | Corsair Hydro H110i Gigabyte RX Vega 64 x2 | Samsung 960 Evo M.2 500GB | Seagate FireCuda SSHD 2TB | Phanteks ENTHOO EVOLV

soxfan335
Protege
NO
hush little babeh dont say a word and nevermind that noise u herrd :shock:

Anonymous
Not applicable
Thanks for the info. That's interesting that the flashing sequence identifies the individual LEDs. It must be a very-high-framerate sensor, I would imagine. With such a wide field of view, I was wondering if it was operating essentially as a detector, rather than an imager, and using the timings and intensities alone, but I can't think of a way to derive position x-y with that. If it is actually generating an image, I wonder what the resolution is and how it relates to accuracy over distance. I imagine that jitter/inaccuracy in rotation will show up far more than in position, though, and either solution sounds very robust for rotational tracking. I do a lot of imaging work (only related to this in the sense that I've worked on some optical tracking) so I was curious how the sensors functioned. If anyone sees any more info out there, I'd be curious to learn more.

PS. Terrifying gif.