Lighthouse

See also: tracking systems

An HTC Vive system shown at CES 2016. The two black Lighthouse base stations are at right.

Introduction

Lighthouse is a laser-based positional tracking system developed by Valve for SteamVR and the HTC Vive. It tracks the position and orientation of a head-mounted display and its controllers in real time, allowing the user to move and re-orient within the range of the base stations. Lighthouse is an outside-in system: fixed base stations placed in the room emit structured infrared light, and photosensors on the tracked devices read that light to compute their own pose. This is the opposite arrangement to inside-out tracking, where the sensors sit on the moving headset and look outward at the environment.

Valve licenses Lighthouse to third-party hardware manufacturers on a royalty-free basis, so that other companies can build compatible headsets and peripherals. The licensing program, branded SteamVR Tracking, opened to outside developers in August 2016.

Lighthouse defined high-end PC VR tracking through the late 2010s, but it has been overtaken by inside-out tracking in newer consumer headsets. In November 2025 Valve confirmed it had stopped manufacturing the Valve Index, the headset most associated with the system, and that its successor, the Steam Frame, would not support external base stations and would instead use onboard inside-out tracking.

How it works

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The reference points for the system are the base stations, small rectangular units placed at the edges of the tracking area. Each base station floods the room with infrared light, and the photosensors on a tracked device use that light to determine where the device is relative to the base stations. Using two base stations placed on opposite sides of the space gives the tracked devices enough information to resolve both position and orientation in 3D.

A first-generation base station contains an infrared LED array (the synchronization flash, sometimes called the Sync Blinker) and two laser emitters mounted on spinning rotors. Sixty times per second the base station fires a global synchronization flash, then sweeps an infrared laser plane across the room along one axis; it then flashes again and sweeps the other axis. The photosensors on the head-mounted display and controllers detect the flash and the laser strike. When a sensor sees the synchronization flash it starts a timer, and the interval until the laser plane reaches it gives the angle of that sensor relative to that axis of the base station. Because the sensors are at fixed, known positions on the rigid body of the device, combining the angles from several sensors yields the full position and orientation of the device.

Base stations require line of sight to the tracked objects and are therefore vulnerable to occlusion. Placing two base stations on opposite sides of the room reduces this problem, and additional base stations can extend the tracking range.

Role of the inertial measurement unit

The Lighthouse optical measurement is fused with data from an inertial measurement unit on the tracked device. The IMU supplies high-rate moment-to-moment motion data, while the optical system provides an absolute positional reference. An IMU on its own accumulates drift over time, so the optical updates are used to correct that drift.

The fusion is also necessary because Lighthouse is a scanning system: a given sensor is struck by the horizontal and vertical sweeps at different instants rather than simultaneously. During fast motion a tracked device can move between strikes, so IMU data is used to update the device pose between optical samples rather than relying on the laser sweeps alone.

SteamVR Tracking 1.0 and 2.0

The original Lighthouse hardware, retroactively called SteamVR Tracking 1.0, used two separate spinning rotors per base station, one sweeping horizontally and one vertically, plus the infrared LED synchronization flash fired roughly every 16.6 ms (60 Hz). A 1.0 setup uses two base stations, which must be synchronized with each other.

SteamVR Tracking 2.0, announced by Valve in June 2017 and shipped from 2018, redesigned the base station to use a single rotor that sweeps both axes, and encodes data directly into the infrared beam, including an identifier for the base station that cast it. Encoding the identity and timing on the beam itself (a feature Triad calls "Sync on Beam") removes the need for a separate synchronization flash and for the base stations to be wired together, which allows more than two units to be combined. The synchronization blinker is the main source of interference between base stations and a significant part of their cost, so dropping it both reduces interference and lowers price. SteamVR Tracking 2.0 supports up to four base stations and a play area of up to about 10 m by 10 m. The second-generation sensor that decodes the on-beam data is Triad Semiconductor's TS4231, which remains backward compatible with 1.0 base stations.

The SteamVR Base Station 2.0 has a field of view of about 160 degrees horizontal by 115 degrees vertical and an effective range of around 7 m, with fixed lasers that sweep about 100 times a second. Using two base stations covers a play area about four times larger than the first generation, and four can be linked for the maximum space. Version 1.0 and 2.0 base stations are not interoperable with each other in a single setup because their synchronization methods differ.

SteamVR Tracking generations

Feature	SteamVR Tracking 1.0	SteamVR Tracking 2.0
Rotors per base station	Two (one per axis)	One (sweeps both axes)
Synchronization	Infrared LED flash (~60 Hz)	Data encoded on the laser beam
Maximum base stations	2	4
Play area	Up to about 5 m by 5 m	Up to about 10 m by 10 m
Light-to-digital sensor	Triad Semiconductor TS3633	Triad Semiconductor TS4231

Sensors and licensing

Valve opened Lighthouse for third-party use through a royalty-free SteamVR Tracking licensing program: companies do not need Valve's permission or pay royalties to embed the technology in their own products. The program opened to outside developers in August 2016; a licensee signs up through Valve's partner portal, and Valve states it charges no licensing fee and requires no certification from Valve before a product ships.

The key component for tracked devices is the Triad Semiconductor TS3633, a "light-to-digital" integrated circuit that takes the signal from a photodiode and converts it into data usable by the SteamVR Tracking algorithms. According to Triad, the chip was Valve's idea, and Valve worked with Triad to define and certify it as the light-to-digital solution for SteamVR Tracking. The TS3633 was offered at about $0.92 per unit in small quantities, falling to roughly $0.49 each at volume, with a TS3633-CM1 prototyping module (chip, photodiode, and resistors) priced at $6.95. The SteamVR Tracking hardware development kit, used by companies designing their own Lighthouse-tracked hardware, was also sold through Triad and started at $595.

Accuracy

Independent measurements have found Lighthouse to be precise. VR researcher Oliver Kreylos measured the stationary jitter of an HTC Vive headset at roughly 0.3 mm with two base stations covering it, rising to about 2.1 mm along an axis covered by only a single base station, and estimated the overall precision at around 1.5 mm RMS and accuracy at around 1.9 mm RMS.

A peer-reviewed study by Niehorster, Li and Lappe (2017) tested the HTC Vive for scientific use. The authors reported high precision, with root-mean-square sample-to-sample jitter below 0.02 cm in position and below 0.02 degrees in orientation, and an end-to-end system latency of about 22 ms. They also found that the tracking coordinate system was tilted relative to the physical ground plane, producing systematic errors in reported height and in pitch and roll, and that losing and regaining tracking could introduce large offsets in the reported pose, which complicated use of a single fixed calibration in experiments involving movement.

Devices using Lighthouse

Several VR headsets and accessories use SteamVR Tracking. The HTC Vive (released April 2016) shipped with first-generation base stations, and the HTC Vive Pro (2018) introduced SteamVR Tracking 2.0. The Valve Index (released June 2019) uses Base Station 2.0. The Bigscreen Beyond (2023), a compact PC VR headset, has no onboard cameras and relies on external SteamVR base stations for tracking; the same is true of its successor the Bigscreen Beyond 2 (shipping from 2025). SteamVR Tracking is also used by add-on trackers worn on the body or attached to objects, including the HTC Vive Trackers and the third-party Tundra Trackers.

The Tundra Tracker, made by Tundra Labs (founded by Luke Beno, a company that supplies chips and development kits for SteamVR Tracking devices), is a general-purpose tracking puck built on the open SteamVR Tracking system. Beno described it as about 60 percent smaller, roughly 50 percent lighter, drawing about 50 percent less power and lasting about twice as long on a charge as HTC's Vive Tracker, at a slightly lower price. It is commonly attached to feet, hips, or other body parts for full-body tracking in social VR.

Tracking volume

See also: Tracking volume

HTC Vive

See also: HTC Vive

With two first-generation base stations the HTC Vive supports a room-scale play space on the order of several metres on a side.

Comparison to inside-out tracking

Lighthouse is an outside-in approach: the optical reference (the base stations) is fixed in the room, and the moving device measures its angle to those fixed beacons. Inside-out tracking instead puts cameras on the headset that observe features in the surrounding room, so no external hardware is required. Outside-in systems such as Lighthouse can deliver high precision and low jitter across a defined volume, but they require mounting and powering base stations and depend on line of sight, which makes them vulnerable to occlusion. Inside-out systems are simpler to set up and portable but historically have been weaker at tracking controllers held outside the headset's camera view.

By the mid-2020s most mainstream consumer headsets, including standalone devices, had moved to inside-out tracking, and the major remaining users of Lighthouse were enthusiast PC VR products such as the Bigscreen Beyond and full-body tracking setups. Valve underlined the shift in November 2025: when it confirmed it had stopped making the Valve Index, it also said the Steam Frame would drop support for external base stations in favour of four monochrome cameras for inside-out tracking, aided by external infrared LEDs for use in darker rooms.

Non-VR applications

Because it provides general-purpose 6DOF indoor positional tracking, Lighthouse has been proposed for uses beyond consumer VR, including embedded robotics control and other precision tracking applications.

History

The chief architect of the Lighthouse tracking system is Alan Yates, an engineer at Valve who invented the device and has used the title "Chief Pharologist" for the project. The technology was demonstrated publicly in 2015 and then opened to third-party hardware makers in 2016. SteamVR Tracking 2.0 followed in 2017 and 2018. Valve discontinued the Valve Index in November 2025 and built its next headset around inside-out tracking, ending Lighthouse's role as Valve's primary tracking method.