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HTC Vive Base Station

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HTC Vive Base Station
Basic Info
VR/AR Virtual Reality
Type Tracking Base Station
Subtype Lighthouse / SteamVR Tracking
Platform SteamVR
Creator Valve Corporation
Developer Valve
Manufacturer HTC
Announcement Date March 2015
Release Date April 5, 2016
Price US$134.99 (single, original retail)
Website https://www.vive.com/us/accessory/base-station/
Versions SteamVR Base Station 1.0 (original); SteamVR Base Station 2.0
Requires Compatible SteamVR headset and controllers, AC power
Predecessor HTC Vive Pre base station (development kit)
Successor SteamVR Base Station 2.0
System
Operating System N/A
Chipset Custom synchronization controller
CPU Embedded
GPU N/A
Storage
Storage N/A
Memory N/A
SD Card Slot No
Display
Display N/A
Resolution N/A
Refresh Rate N/A
Image
Field of View N/A (emitter; ~120 degrees swept coverage)
Horizontal FoV N/A
Vertical FoV N/A
Optics
Optics Rotating infrared laser emitters (two rotors)
Ocularity N/A
IPD Range N/A
Adjustable Diopter N/A
Passthrough N/A
Tracking
Tracking Outside-in optical (emits IR for headset/controller sensors)
Base Stations Two for full room-scale (maximum two for 1.0)
Eye Tracking N/A
Face Tracking N/A
Hand Tracking N/A
Body Tracking N/A
Rotational Tracking Enables 6DoF on tracked devices
Positional Tracking Enables 6DoF on tracked devices
Audio
Audio N/A
Microphone N/A
Camera N/A (no camera; laser/IR emitter)
Connectivity
Connectivity Optical sync (wireless) or sync cable
Ports Sync cable port, DC power
WiFi No
Bluetooth No
Power External AC adapter (DC 12V, ~2.5A)
Battery Capacity N/A (wall-powered)
Battery Life N/A
Charge Time N/A
Device
Dimensions Approx. 6.1 x 6.2 x 5.0 in (155 x 158 x 127 mm)
Weight Approx. 0.45 kg (1 lb)
Material Plastic housing
Headstrap N/A
Haptics N/A
Color Black
Sensors Photodiode for optical sync; IR LED strobe array
Input Channel selector (b / c / A), sync cable jack
Compliance SteamVR Tracking 1.0

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The HTC Vive Base Station is a positional tracking device that powers the room-scale tracking of the original HTC Vive Virtual Reality system. Released on April 5, 2016, it is a consumer implementation of the Lighthouse tracking technology developed by Valve Corporation and is also marketed as the SteamVR Base Station 1.0.[1][2] Rather than containing a camera, each base station is an infrared laser emitter: it floods the play area with timed sweeps of non-visible light that are detected by photosensors built into the HTC Vive headset and its motion controllers, allowing the SteamVR software to compute their position and orientation with sub-millimeter precision.[3][4] A standard setup uses two base stations mounted in opposite corners of a room, and the pair shipped inside the US$799 launch bundle for the HTC Vive alongside the headset and two wireless controllers.[1][2]

Because the base stations sit at fixed points outside the user and the sensors are on the tracked objects, the approach is described as "outside-in" tracking. This was the dominant high-end Virtual Reality tracking method during the first generation of consumer PC VR, and the same hardware was reused across later SteamVR devices including the HTC Vive Pro, the Valve Index, and the Vive Tracker.[5][6]

History and development

The Lighthouse system underpinning the base station was first shown publicly in early March 2015 when Valve Corporation and HTC revealed the Vive at the Game Developers Conference and Mobile World Congress.[7] Valve engineer Alan Yates was a lead engineer on the Lighthouse hardware, and the company later chose to license the tracking technology to third parties on a royalty-free basis (with licensees paying only for a training course) to encourage an ecosystem of compatible hardware.[8][9] Early "Vive Pre" developer units used larger base stations; the retail unit gained a 1/4 inch tripod mounting thread for easier placement.[10]

HTC confirmed the consumer pricing in February 2016: the complete Vive package cost US$799 and included the headset, two wireless controllers with haptic feedback, and two Lighthouse base stations, with pre-orders opening on February 29 and shipping beginning April 5, 2016.[1][2] The bundle positioned room-scale tracking, the ability to walk around a physical space and have that movement mirrored in VR, as the system's defining feature.[1]

In 2018 a redesigned second generation, the SteamVR Base Station 2.0, launched alongside the Valve Index and the HTC Vive Pro ecosystem. It is not cross-compatible with the 1.0 units in the same play space.[6][11]

How it works

Each base station contains two brushless, permanent-magnet, three-phase synchronous motors, each spinning a lens assembly at roughly 3,600 RPM.[12] Sixty times per second the station fires a global infrared strobe (a synchronization "flash") and then sweeps a laser line across the room; it then flashes again and sweeps the second laser along the perpendicular axis.[3][12] The two rotors handle the horizontal and vertical sweeps respectively, and the synchronization blinks occur every 8.33 ms (120 Hz) while each individual axis is swept at 60 Hz.[12]

The photosensors distributed across the headset and controllers each record the precise time between the synchronization flash and the moment a laser line passes over them. Because the geometric layout of the sensors on each device is known in advance, the differences in these arrival times let the system solve for the angle of every sensor relative to the base station, and therefore the full position and orientation of the device.[3][12] High-speed inertial measurement units (IMUs) inside the headset and controllers fill the gaps between optical updates to keep tracking smooth and low-latency.[4]

Independent analysis of the system measured tracking jitter of around 0.3 mm when both base stations were visible, with precision on the order of RMS 1.5 mm and accuracy around RMS 1.9 mm, figures good enough that the setup could double as a large-area 3D digitizer.[4] The first-generation tracked devices used discrete photodiode receiver circuits (around 41 components per sensor) to decode the laser sweeps; Valve later worked with Triad Semiconductor on a single light-to-digital chip, the TS3633, to simplify that sensor design for licensees and future hardware.[13]

Setup and synchronization

For full room-scale coverage the two base stations are mounted high (above head height) in opposite corners of the play area, angled downward toward the center, and connected to AC power.[10][14] The 1.0 generation supports a maximum of two units in a single space and provides a tracked area of roughly 3.5 m by 3.5 m (about 11 ft 5 in square).[5][14]

The two stations must stay synchronized so their sweeps do not collide. They can do this optically, with a photodiode on each unit watching the other's flashes, or over a wired sync cable when line of sight between the stations is blocked (for example by a fixture hanging from the ceiling).[12][14] A channel selector on the back of each unit sets its role: in a wireless pair one station is set to channel "b" and the other to channel "c", while a wired pair uses channels "A" and "b".[14] A single base station used alone is typically set to channel "A".[14]

Specifications

Specification HTC Vive Base Station (1.0)
Type Infrared laser tracking base station (Lighthouse / SteamVR 1.0)
Tracking method Outside-in optical; emits IR sweeps detected by device sensors
Rotors / motors Two brushless three-phase motors, ~3,600 RPM
Sweep / sync timing 60 Hz per axis; 120 Hz synchronization flash
Maximum units 2 per play space
Tracking area Approx. 3.5 m x 3.5 m
Synchronization Optical (wireless) or sync cable; channels A / b / c
Power External AC adapter, DC 12 V (~2.5 A); low draw in normal use
Power cable length Approx. 3.5 m (11 ft 6 in)
Dimensions Approx. 155 x 158 x 127 mm (6.1 x 6.2 x 5.0 in)
Weight Approx. 0.45 kg (1 lb)
Mounting Wall mount or 1/4 in tripod thread
Compatibility HTC Vive, HTC Vive Pro, Valve Index, Vive Tracker and other SteamVR devices
Original retail price US$134.99 (single); included as a pair with the US$799 Vive

Versions

The base station exists in two incompatible hardware generations. The original 1.0 unit described above uses two rotating laser emitters and optical or cabled synchronization between exactly two stations. The later SteamVR Base Station 2.0, introduced in 2018 with the Valve Index and HTC Vive Pro lineup, simplified the design to a single rotor that splits its light into two beams and encoded the synchronization data directly into the infrared light to remove the need for the sync cable.[6] Valve also lists a wider field of view and improved range for the 2.0 unit.[11] The 2.0 generation supports more stations in a single setup (up to four), enabling a larger tracked volume of roughly 10 m by 10 m (about 33 ft by 33 ft).[11]

Feature Base Station 1.0 Base Station 2.0
Introduced 2016 2018
Rotors Two One (split into two beams)
Synchronization Optical or sync cable Wireless, encoded in IR (no cable)
Max units per space 2 4
Tracking area ~3.5 m x 3.5 m ~10 m x 10 m
Cross-compatible with other generation No No

Reception

At launch the Lighthouse-based tracking of the HTC Vive was widely regarded as the most accurate and reliable consumer VR tracking available, and reviewers credited the base stations with enabling convincing room-scale experiences that distinguished the Vive from camera-tracked rivals of the era.[1][4] Subsequent independent testing confirmed millimeter-level precision across the play space.[4] The main practical drawbacks were the need for mains-powered external emitters, careful placement with line of sight to the user, and the cabling or wireless sync setup, points later addressed in part by the 2.0 redesign and by the rise of camera-based inside-out tracking in standalone headsets.[6]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Cite error: Invalid <ref> tag; no text was provided for refs named rtvr2016
  2. ↑ 2.0 2.1 2.2 Cite error: Invalid <ref> tag; no text was provided for refs named engadget2016
  3. ↑ 3.0 3.1 3.2 Cite error: Invalid <ref> tag; no text was provided for refs named rtvr-inner
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Cite error: Invalid <ref> tag; no text was provided for refs named rtvr-accuracy
  5. ↑ 5.0 5.1 Cite error: Invalid <ref> tag; no text was provided for refs named vrcompare
  6. ↑ 6.0 6.1 6.2 6.3 Cite error: Invalid <ref> tag; no text was provided for refs named mixed
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named rtvr-retro
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named toms-license
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gamedev-yates
  10. ↑ 10.0 10.1 Cite error: Invalid <ref> tag; no text was provided for refs named basestations-wiki
  11. ↑ 11.0 11.1 11.2 Cite error: Invalid <ref> tag; no text was provided for refs named valve-bs
  12. ↑ 12.0 12.1 12.2 12.3 12.4 Cite error: Invalid <ref> tag; no text was provided for refs named pcper
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named rtvr-triad
  14. ↑ 14.0 14.1 14.2 14.3 14.4 Cite error: Invalid <ref> tag; no text was provided for refs named arvrtips
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