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Lighthouse is Valve’s laser-based tracking system that forms the bedrock of Steam VR’s input system. Alan Yates, Hardware Engineer at Valve was a key player in the system’s design and implementation. Alan, frustrated with being asked the same questions over and over on Twitter, produced a nano-FAQ on Lighthouse. Here are the highlights.

Don’t worry – you’re not alone. I had no idea what a Pharology was either. It’s the term given to the scientific study of lighthouses, signal lights, their construction and illumination. It’s also forms part of the tongue-in-cheek job title Alan Yates, a Hardware Engineer at gaming giant Valve, that served as a knowing nod to the company’s secretive ‘Lighthouse’ project in which Yates has been actively involved prior ro it’s unveiling at GDC this year.

Lighthouse is a 3D spatial laser-tracking system designed by Valve primarily to solve hard problems surrounding virtual reality positional tracking, be it for their new Steam VR head mounted displays, such as HTC’s Vive or controller input for games based in Steam VR’s ecosystem. There are a lot of questions surrounding the system, which uses one or more laser-point producing ‘base stations’ which scan the room creating laser reference points which are picked up by sensors on controllers or headsets.

Since the system’s launch at GDC 2015 this week, Alan has clearly got a little tired of asking the same question over and over via social media and so produced a nano-FAQ comprising answers to questions he’s now regularly asked.

Use the navigation arrows above to move through the tweets.

1 : Like all optical systems occlusion is a limiting factor. Spatial redundancy is very helpful, but finger tracking will be challenging.

— Alan Yates (@vk2zay) March 6, 2015 2 : While it can be used with single sensors and without an IMU, the IMU reduces its latency. — Alan Yates (@vk2zay) March 6, 2015 3 : Lighthouse was designed from day one to be scalable, you can in principle concatenate tracking volumes without limit like cell towers. — Alan Yates (@vk2zay) March 6, 2015 4 : There are many modes Lighthouse can operate in, so far you’ve only seen one.

— Alan Yates (@vk2zay) March 6, 2015 5 : Two or more base station visibility lets you track a single sensor, which may be on a non-rigid object. — Alan Yates (@vk2zay) March 6, 2015 6 : One base station is enough to track a rigid object with an IMU, five sensors need to be visible to acquire a pose, but it can hold with less

— Alan Yates (@vk2zay) March 6, 2015 7 : Lighthouse base station emissions are Class 1 (unconditionally eye safe), while it contains class 3 sources they are enclosed & interlocked. — Alan Yates (@vk2zay) March 5, 2015 8 : The future of tracking systems for VR is not a single tracker, but combinations of the right tech for each part of the job.

— Alan Yates (@vk2zay) March 6, 2015 9 : Lighthouse is not the dual of a camera: The “dots” know their ID; the hardware gives you angles directly. Pose calc’ can be decentralised. — Alan Yates (@vk2zay) March 6, 2015 10 : We’ve joked about using mirrors to get more coverage with virtual base stations in the left-handed mirror universe… Probably too hard.

— Alan Yates (@vk2zay) March 6, 2015

We’ll be bringing you first hands experience using Lighthouse as part of Valve’s Steam VR demos very soon as the Road to VR team continue to report back from GDC 2015 in San Francisco.