Vive Trackers Experiments – Half 2: Setup, Props, and Full Physique Digital Actuality

Immediately I host one other wonderful article by the VR ergonomics professional Rob Cole, which has already written on this weblog wonderful posts, just like the sequence concerning the ergonomics of the Valve Index or the viral article concerning the wonderful Caliper VR controllers he labored on by himself.

Just a few weeks in the past, he wrote right here an in depth article on the Vive Trackers, and now he’s finishing it with this new article, which is an extended and detailed story of his experimentations with the Trackers and their use instances, and particularly their massive potential for full-body VR. It’s going to be a really fascinating publish, so learn it till the tip!


Disclaimer: HTC supplied three of their Vive Tracker 3.0 models for my use in these articles.

What’s an HTC Vive Tracker?

As described in my first HTC Vive Tracker article earlier this 12 months:

“Vive Tracker is a wi-fi, battery-powered SteamVR tracked accent that gives extremely correct, low latency 6 Levels of Freedom (6DoF) movement monitoring inside a roomscale setting.”

(Picture by Rob Cole)

Or in HTC’s personal phrases:

“Monitor motion and produce objects from the actual world into the digital universe”.

While the primary a part of this text appeared on the historical past of the HTC Vive Tracker and its three completely different variations, the second half will give attention to some sensible experiments with the newest HTC Vive Tracker 3.0

First although, a fast dive into the extra technical facet of the HTC Vive Tracker 3.0 for many who are excited about how this stuff work. 

Vive Tracker monitoring

The HTC Vive Tracker 3.0 is a SteamVR-compatible machine, utilizing Valve’s second-generation (2.0) base station monitoring know-how. To grasp the general idea, the primary era of 1.0 base station monitoring was described on this manner by Valve

“How It Works: The SteamVR Monitoring Basestations sweep the room with a number of sync pulses and laser strains, reaching out to about 5 meters. By conserving cautious monitor of the timings between pulses and sweeps, the SteamVR Monitoring system makes use of easy trigonometry to search out the situation of every sensor to inside a fraction of a millimeter. By combining a number of sensors, 2 basestations, in addition to including a high-speed IMU (inertial measurement unit), SteamVR additionally calculates the tracked object’s orientation, velocity, and angular velocity, all at an replace price of 1000Hz.”

(Picture supplied by Rob Cole)

In April 2018 HTC launched the Vive Professional headset, Professional controllers, and Vive Tracker 2.0 every fitted with next-generation optical sensors and up to date electronics. Second-generation base station (2.0) monitoring had developed by eliminating one rotor and encoding the beam. This technical distinction is effectively described by Redditor /u/Crozone:

“The laser will encode the bottom station ID in addition to the present laser sweep angle. There isn’t a longer a ‘timing pulse’, the bottom station does the timing internally and sends the angle on to the Vive on the laser. Which means each time the Vive detects a laser on any sensor, it already is aware of the bottom station that’s sending that laser, in addition to the precise angle of that laser from the bottom station. This additionally implies that the bottom stations don’t must sync in any respect, and the Vive doesn’t even must time something.”

(Picture by Rob Cole)

Launched in March 2021, Vive Tracker 3.0 is a smaller, extra power-efficient evolution of the two.0 Vive tracker, offering longer battery life and fewer mass / inertia when shortly transferring round. 

HTC Vive Tracker 3.0 has 18 optical sensors, rigorously positioned throughout a specifically designed form that developed from the unique Vive controller, and has since been shrunk in measurement. The form of the Vive Tracker 3.0 maximizes the variety of non-co-planar sensors that the bottom station rays can illuminate, to supply extremely correct (sub mm) roomscale 6DoF monitoring that’s extremely proof against occlusion.

It’s not unusual to obscure a number of sensors throughout motion in roomscale periods: having 18 sensors at completely different angles goals to attenuate this drawback, and works very effectively in the actual world.

(Picture by Rob Cole)

Every sensor is hidden behind an optical window constructed from a particular plastic manufactured to cut back stray seen gentle and reduce the impact of reflections while offering a transparent optical path for infrared rays emanating from the bottom stations.

With HTC Vive the sensor window has been a part of their design language because the first Vive SteamVR package in 2016, this was continued with Vive Professional, Vive Trackers, and Vive Professional 2.

Whereas holding the Vive Tracker it’s very straightforward to see the sensor areas positioned throughout the complete machine. Valve and Pimax SteamVR merchandise as an alternative have refined sensor home windows with optical materials co-molded right into a structural casing: typically a feint circle is all that may be seen.

Every SteamVR tracked machine has “recognized bodily geometry” which incorporates the precise place and orientation of every optical sensor relative to the article’s bodily heart, making a “sensor mesh” inside the bodily bounds of the tracked object.

(Picture by Rob Cole)

The picture above, clearly an homage to the legendary Unity Dice, demonstrates the place and orientation of optical sensors throughout completely different surfaces of the article… this might be certain that sensors are all the time out there as the article is turned or moved.

Controllers, headset, and trackers are individually calibrated to a excessive diploma of accuracy after manufacturing, as small variations exist when manufacturing plastic casings and when putting particular person sensors into the casing. For instance, the calibration knowledge of a single sensor is that this one:

mannequin Factors [ -0.00322245085, -0.0423639342, 0.110276416 ]

mannequin Normals [ -0.0380270146, -0.700318217, -0.712817252 ]

“Factors” are three-d co-ordinates for the sensor, while “Normals” are the relative orientation of the optical sensor’s centroid (light-facing floor). A tool that isn’t correctly calibrated can undergo from poor monitoring efficiency or failure in addition. I’ve learn that preliminary sensor placement must be inside 1mm of the plotted Level location for SteamVR’s software to work with in the course of the calibration section (that is performed post-assembly).

This excessive diploma of geometric accuracy permits the host pc to simply decide the precise orientation and relative place of the tracked object as a result of it might examine incoming angular knowledge in opposition to the geometry of the tracked object to decide its place within the roomscale three-d area, and its orientation inside that area.

(Picture by Rob Cole)

The picture above reveals optical sensor hits being detected on the Vive Tracker from a 2.0 base station on the wall above the playspace. If the Tracker is turned, sensors turn out to be occluded, inflicting the information to vary in actual time. The areas of the optical home windows for every sensor can clearly be seen throughout the casing of the Vive Tracker.

Optical sensor hits are mixed with route, acceleration, and gravity knowledge from an onboard IMU (inertial measurement unit). The IMU itself is a 9DoF unit, working at a a lot increased polling price (1000hz) than the optical sensor system (100hz). The IMU used on the Vive Tracker is widespread to 6DoF tracked objects, utilizing a 9-axis movement monitoring machine. An instance is described by market chief TDK of their InvenSense IMU:

“InvenSense’s 9-Axis gadgets mix a 3-axis gyroscope, 3-axis accelerometer, and 3-axis compass in the identical chip along with an onboard Digital Movement Processor™ (DMP™) able to processing the complicated MotionFusion algorithms.”

(Picture by TDK, supplied by Rob Cole)

Nevertheless, IMU gadgets undergo from small knowledge errors which begin to compound over time: with out correction (world reference) IMU primarily based gadgets are inclined to “drift away” from their start line, or turn out to be disorientated, one thing skilled with older 3DoF VR methods which required common recalibration. 

The lighthouse optical system of SteamVR subsequently offers an angular “world reference” at 100hz for 1000hz IMU primarily based methods, offering error correction for IMU drift with an correct provision of place and pose throughout a big dimensional tracked quantity.

The picture under reveals a Vive Tracker outputting stay gyro and accelorometer knowledge utilizing a operate in “Lighthouse Console” (a command line interface). If you happen to transfer bodily the machine round you’d see the information instantly altering to mirror your real-world actions.

(Picture by Rob Cole)

The info is distributed wirelessly again to the host PC by means of a USB-mounted Vive “Dongle”.  The Dongle communicates with a wi-fi chip contained in the Vive tracker by means of a proprietary model of Nordic Enhanced Shockburst on the two.4 GHz frequency. As described by the producer:

“Enhanced ShockBurst (ESB) is a fundamental protocol supporting two-way knowledge packet communication together with packet buffering, packet acknowledgment, and computerized retransmission of misplaced packets. ESB offers radio communication with low energy consumption, and the implementation is small in code measurement and simple to make use of.” 

SteamVR monitoring operation is general very environment friendly: it minimizes calculation, energy, and communications load on the host PC. One other massive benefit of lighthouse base station monitoring is not any direct connection is required between the bottom stations and the host PC, since the bottom stations are self-contained “dumb” emitters.

Which means your PC might be in one other room, in case your cabling is lengthy sufficient, and you’ll put a number of tracked gadgets into that room, every utilizing the identical base station to supply correct monitoring. Base Station 2.0 additionally helps as much as 4 base stations in a single room, offering as much as 10 m x 10 m protection.  

The JSON

When every SteamVR machine is constructed and calibrated, all the information is written to a file Valve calls “the JSON”: successfully the on-board driver, the JSON is exclusive to every completely different tracked machine.

Every tracked machine has a novel serial quantity generated by an onboard CPU, while the file incorporates extremely correct geometry of all machine sensors, USB machine id, IMU setup, and system info for SteamVR to grasp what the machine is and how one can work together with it.

Lastly, it’s widespread to see some “firmware” references within the JSON. On the Vive tracker this appears to be associated to energy administration while on different {hardware} like Index controllers it’s primarily associated to finger monitoring and grip sensors. I’ve damaged completely different areas into colours to make it simpler to grasp:

(Picture by Rob Cole)
  • RED: Gadget id for USB interface
  • ORANGE: SteamVR gentle home info
  • GREEN: Firmware (“embedded” applications in {hardware})
  • YELLOW: Head orientation (orientation)
  • PURPLE: IMU (gyro) setup totally calibrated
  • AZURE: Channel Map (listing of bodily connections to sensors)
  • LIGHT GREEN: ModelNormals (orientation of every sensor) totally calibrated
  • LIGHT PINK: ModelPoints (three-dimensional place of every sensor) totally calibrated

One specific merchandise of curiosity for my experiments is the render mannequin reference (within the orange part), as a result of it tells SteamVR the place to search for a file saved on the host PC that gives the render mannequin that’s seen because the digital illustration of your machine in VR. If we alter the render mannequin we are able to inform the Vive Tracker to show one thing else that doesn’t seem like a Vive Tracker.

Warning: You’ll be able to obtain the JSON from any SteamVR machine utilizing Lighthouse console, however be sure to retailer its distinctive JSON someplace protected and don’t get it combined up with different JSON information.

Importing an improperly configured or corrupted JSON file, or attempting to repair a problem by copying the JSON from one other machine (i.e. one other Vive tracker) will are inclined to cease the machine from working, as this particular person on Reddit not too long ago came upon:

“Hey all, In a determined try to repair a bugged tracker, I flashed a 3.0’s config onto a 2.0 and now SteamVR gained’t discover the two.0 tracker in any respect. It reveals up as a tool, however is caught in looking out?”

Attaching the Vive Tracker

As talked about throughout my first article, the Vive Tracker 3.0 is hooked up utilizing 1/4” screw thread digital camera model “docking mechanism” with stabilizing pin (ISO commonplace ISO 1222:2010).

(Picture supplied by Rob Cole)

Docking Mechanism

-1/4” Screw nut to lock the accent.
-Stabilizing pin recess for constraining the tracker from rotating.
-Pogo pin port (spring contact-type) for non-compulsory electrical connection to the accent.
-Friction pad to supply a floor with friction between the accent and VIVE Tracker (3.0)

Electrical pogo pins

The underside of the Tracker has six “pogo pin” contacts permitting electrical indicators to move between the Tracker and any appropriate peripheral gear. This enables {hardware} builders to position appropriate buttons on tracked objects and use the Tracker to ship this knowledge again to the PC.

HTC’s Marios Bikos: “The HTC VIVE Tracker means that you can not solely monitor objects in VR (getting tracker pose in real-time) but in addition use the POGO pins to simulate enter buttons (Grip/Set off/Trackpad/Menu) as if you happen to have been utilizing a Vive controller.”

The picture under reveals a structure of the pogo pins, with Pin.3 because the Grip button, Pin.4 because the Set off button, Pin.5 because the Trackpad button, Pin. 6 because the Menu button.

(Picture by HTC, supplied by Rob Cole)

Through the years because the launch of the Vive Tracker, numerous fans and hobbyists have made pogo pin connectors for the Tracker, and there are various examples discovered on-line displaying the completely different approaches taken. To make use of the Vive Tracker with lively pogo pin inputs you must comply with the recommendation, once more from Marios Bikos:

“The one option to get enter from the Vive Tracker’s POGO pins on this situation is to vary the tracker position to “Held in hand” and choose Left/Proper relying on how we plan on utilizing the Vive Tracker.”

(Picture by Rob Cole)

There’s a wealth of neighborhood info discovered on-line about improvement with the Vive Tracker, however one of the best start line is probably to have a look at HTC’s Vive Tracker Developer pointers which might be discovered right here: https://developer.vive.com/documents/850/HTC_Vive_Tracker_3.0_Developer_Guidelines_v1.1_06022021.pdf

If not utilizing the pogo pins, for instance utilizing a Tracker for full physique monitoring the place it’s not hooked up to an object with electrical inputs (however a tender strap for physique attachment), then it’s hooked up utilizing an appropriate 1/4” screw and rubber pad, ideally with stabilizing pin to cease the tracker from rotating across the mount.

If no pin is accessible then rotating the tracker into the rubber pad offers sufficient friction it most likely gained’t come free even when dancing frantically in VR Chat.

Dongles and cabling

Every Vive Tracker requires its personal USB Dongle, as every distinctive Tracker and Dongle are paired collectively in the course of the controller pairing process in SteamVR.

It’s now doable to have as much as 9 trackers working although it will most likely trigger USB havoc on most PC methods, so some correct analysis could be required to get the best USB cables and PCI-E card.

Every Vive Tracker is provided with a USB cable, Vive Dongle and Dongle base; the USB cable is 1.2 meters size, to supply far between your PC and the Dongle, in an effort to reduce electrical interference from the PC.

(Picture by Rob Cole)

Nevertheless, this is probably not sufficient to get the Dongle into your playspace, relying in your VR setup. For my home setup, I’ve a 3m x 3m playspace however my PC sits exterior the room on a trolley with the headset tether passing beneath the door.

The usual 1.2 meters cable (proper facet, picture above) is far too brief to get the Dongle from my PC, beneath the door and into my playspace. This was shortly solved utilizing a 5 meters lengthy lively USB 2.0 cable extender left over from my possession of an Oculus Rift CV1 with a 3-camera monitoring setup.

After buying one other lively USB 2.0 cable extender of the identical model from Amazon for £10, it was straightforward to make use of the USB extension cables to position two Vive Tracker dongles proper into my playspace, by passing beneath the door alongside the headset tether. The extension cables are proven on the prime and on the left facet within the picture above.

The usage of an lively extension cabling ensures a steady USB connection over an extended cable run, as you don’t need USB instability inflicting your Trackers to maintain disconnecting. Your mileage with USB stability will fluctuate relying on the standard of your motherboard and its means to assist a number of connections; it’s possible you’ll want a PCI-E card or related answer if having USB connectivity points.

The third Vive Tracker dongle was simply related by plugging it into the “Frunk” of my Index headset. For non-Index house owners, a 3rd USB extension cable could be required. In case your PC is inside your playspace it’s possible you’ll not want cable extensions, however they might let you optimize the position of your Dongles with out compromising the place of your PC, so effectively price taking a look at for a small value. 

A dongle contained in the “funk” (Picture by Rob Cole)

With all three Vive Tracker dongles lastly related, my PC recognised them as USB gadgets. Now it was time for the setup in SteamVR.

Pairing in SteamVR

Vive Trackers are paired similar to Vive or Index controllers: beneath “gadgets” and “pair controller”, you’ll find the Vive Tracker choice, so simply comply with the easy-to-understand on-screen directions.

(Picture by Rob Cole)

A number of seconds later you must discover your Tracker paired with a Dongle and glowing regular inexperienced (as seen within the photos under). If it doesn’t pair, be sure your Dongle is inside attain of the Vive Tracker, to allow them to simply discover one another. For pairing issues, there’s a whole lot of technical info on-line each from HTC and the SteamVR neighborhood. 

(Picture by Rob Cole)

As soon as every Tracker was paired (a complete of three in my case) I may see all operational SteamVR gadgets within the menu proven under. I’ve labeled these in several colours to focus on what sort of machine every one is, while small icons make it straightforward to determine at a look.

(Picture by Rob Cole)

Going additional into the menu reveals “Handle Trackers” which offers an inventory of the fourteen completely different tracker areas and choices. These mirror the physique areas (i.e. left and proper foot) in addition to offering single areas for the chest and the waist.

(Picture by Rob Cole)

The completely different wearable (physique) choices are demonstrated by our picket good friend under, displaying the excessive diploma of precision that’s doable given sufficient Vive trackers and USB bandwidth:

(Picture by Rob Cole)

Along with the body-worn areas, you may also select:

  • Disabled (ignore)
  • Digital camera
  • Keyboard

My three lively Vive Trackers are proven within the picture under, with areas assigned for full physique monitoring in VR Chat and related functions. I’ve scrubbed off the serial numbers of the trackers however often, that is one thing like “LHR-A8368513”. You’ll be able to see the roles assigned to every tracker: “Left foot”, “Waist”, and “Proper foot”.

(Picture by Rob Cole)

First time – What do you see?

As quickly as you place your headset on and check out pausing SteamVR dwelling, you’ll instantly see any lively Vive Trackers proven as high-resolution render fashions with glowing indicators. In case you are utilizing a Vive Tracker assigned as “held in hand”, you possibly can maintain it, rotate it, transfer it round which could be very cool and instantly cements the thought of a “tracked object” within the person’s mind.

The photographs under have been shot by means of the lens of my Index headset… I apologize for the distortions, but it surely’s onerous to {photograph} the twin compound lens with a smartphone! The left picture reveals a single Vive Tracker with Index controllers while the best picture reveals a waist-mounted Vive tracker in addition to left-and-right-feet mounted Vive Trackers.

(Picture by Rob Cole)

Unpausing SteamVR will trigger the Vive Trackers to vanish from the view inside your headset, and also you gained’t see them once more until pausing or utilizing an utility designed to work with them, often swapping their render mannequin for an in-game object (for instance a gun or tennis bat).

The sensible experiments

I attempted a bunch of various stuff together with:

  • Attaching to purchased objects
  • Discovering some video games to play
  • Attaching to a customized object
  • Full Physique Monitoring setup utilized in VR Chat.

Attaching to purchased objects

(Picture by Rob Cole)

Nicely, this plan got here unstuck shortly as it wasn’t doable to purchase a Vive-tracker-compatible gun within the UK anymore. Each Amazon and Ebay redirected me to sellers within the USA, however by the point Worldwide delivery and gross sales taxes have been added it was getting near £100, which was getting a bit costly for taking part in just a few rounds of Arizona Sunshine.

Even Laptop Change didn’t have something second hand, although their inventory continually modifications so I arrange a number of inventory alerts on their web site. Different manufacturers that supplied assault rifles and pistols for Vive Trackers had discontinued their merchandise, with no present alternate options out there.

There appeared to have been a flurry of peripheral exercise on this area throughout 2016-2017, following the launch of the HTC Vive, earlier than it went chilly most likely as a consequence of restricted gross sales.

Even when each SteamVR buyer had purchased a Tracker and peripheral within the first 2 years, that might nonetheless have been a really small person base within the grand scheme of {hardware} gross sales. Tooling up injection mould tooling and meeting isn’t cheap even for a easy gun design.

(Picture by Rob Cole)

These guys are nonetheless providing their gun for $899, however with the next considerably complicated caveat (quoting actual phrases):

  • The supply is Vive Gun VR + tracker 1.0 model= 100% good GamePlay.
  • As a result of newest model vive tracker 2.0 launched in 2018, it’s not appropriate with Vive gun completely, that lacking operate under: 1- Unusable with trackpad operate on vive gunVR. 2- Shorter battery life on tracker 2.0 and may’t cost by vive gunVR instantly in sport taking part in.

Trying additional into this, some opinions on-line complained about compatibility issues with later updates of SteamVR breaking one thing that was by no means mounted. I’m assuming this pertains to the pogo pin inputs utilized by the completely different manufacturers and fashions of gun, but it surely was unclear precisely what had gone fallacious.

“1.0 out of 5 stars. Reviewed in the US on 27 December 2019. Waste of $160 for the gun and tracker. Doesn’t work with any video games.”

Some customers talked about having to make use of an earlier model of SteamVR to get their weapons to work, although this then didn’t appear to work for Valve Index headset customers who required a later construct of SteamVR.

With the comparatively excessive pricing and appreciable trouble of returning an imported gun if it didn’t work correctly, I didn’t waste any additional time wanting into this. I had fond recollections of utilizing a Vive-tracked gun in co-operative Arizona Sunshine at a VR Arcade some years in the past, and left it at that!

Anybody for Tennis?

The opposite choice for an simply purchased object was “HTC’s Racket Sports activities Set” which they’ve stopped promoting on Amazon and solely appear to promote instantly as a particular merchandise. I did have a look at shopping for the Tennis and Ping Pong sport “Digital Sports activities” (which comes free with the set) but it surely appeared unique to Viveport because it wasn’t out there on Steam.

https://www.viveport.com/apps/66bdf791-c7d1-44e3-aaf4-4bdc2ee7215a

The Racket Sports activities set incorporates 2 different-sized plastic props with sensible grips, there isn’t a “pogo pin” connection because it doesn’t require button enter (you’d use a Vive or Index controller to launch and management the applying).

The paddle and racket present a a lot nearer feeling of weight and inertia in comparison with waving a controller about and eradicating weak, costly controllers from the playspace in favor of utilizing a harder / cheaper plastic racket and Vive Tracker.

(Picture by HTC, supplied by Rob Cole)

PADDLE

  • Weight with out Tracker: 4.9 oz.
  • Measurement: 6″ W x 10″ H x 1″ D
  • Connection: 1/4-inch UNC threaded mount (commonplace tripod mount)
  • Security: Lanyard strap

RACKET

  • Weight with out Tracker: 10.8 oz.
  • Measurement: 4.75″ W x 15.75″ H x 1.5″ D
  • Connection: 1/4-inch UNC threaded mount (commonplace tripod mount)
  • Security: Lanyard strap
(Picture by Rob Cole)

Trying on the listing of Racket Sports activities Set appropriate video games, you possibly can see the bulk are from the early days of the HTC Vive client launch, releasing in 2016 after which 2017. Some haven’t been up to date since launch, while others have acquired a few updates.

Fortunately I discovered all these titles out there on Steam for individuals who don’t have Viveport entry. This listing reveals the discharge date and present pricing.

  • Holoball, 2016, £10.99, free demo
  • Racket NX, 2018, £15.49
  • Selfie Tennis, 2016, £7.19
  • Racket Fury, 2017, £15.49
  • Blobby Tennis, 2016, freed from cost
  • VRSquash, 2017, £14.49
  • First particular person Tennis, 2019, £19.49
  • Paddle Up, 2016, £6.99

To attempt utilizing a racket sport with one in all my Vive Trackers, I downloaded demos of Racket NX and Blobby Tennis, then I constructed myself a racket for the Tracker utilizing a spare ping-pong bat. That is what occurred.

(Picture by Rob Cole)

I couldn’t get the Racket NX demo to work correctly if simply utilizing a Vive Tracker. With no set off, I couldn’t really begin the sport. It additionally appeared to require a set off motion to “pull” the ball towards the bat.

It was straightforward to play Racket NX utilizing an Index controller and it was enjoyable, however it wouldn’t enable me to have an lively Index controller in a single hand and the Vive Tracked bat within the different, it simply ignored the bat utterly. I attempted adjusting this drawback within the controller settings, however no controller settings have been really out there. Nevertheless the complete sport is bound to characteristic settings and far more so it may very well be price revisiting.

Mr. Blobby Tennis

I used a Valve Index controller in my left hand to throw the ball, and the Vive Tracker fitted within the bat held in my proper hand to manage the tennis racket. This appeared very fundamental however felt actually enjoyable with a “blob” opponent on the opposite facet of the online sometimes returning my horrible serves.

(Picture by Rob Cole)

Regardless of me holding a picket dealt with ping pong bat with a tracker hooked up, the in-game tennis racket didn’t really feel too dissimilar as a result of really feel of “holding a deal with” as an alternative of gripping a plastic movement controller physique at an odd angle.

I then determined to elongate the deal with of my “bat” to make it really feel extra like a tennis racquet which instantly helped issues really feel extra balanced.

(Picture by Rob Cole)

As quickly as I received used to utilizing my longer paddle I began to turn out to be more adept, typically making a dozen returns earlier than hitting one straight into the online or splicing it off at a random angle.

Regardless of the strong ping-pong bat considerably obscuring the Vive Tracker from the second base station, I had no points with monitoring, which was shocking. The primary base station had clear line of sight of the Vive Tracker on the bat, while fast hand actions supplied a wealthy stream of IMU knowledge, particularly acceleration. 

Rays from the second base station would have hit some sensors on the perimeters of the Tracker because the bat angle modified throughout my motion. A “hole” (reduce out) bat paddle would have uncovered extra sensors on the Tracker to the second base station, which is what HTC has performed with their plastic racket set. 

Shortly although, I noticed my 3 x 3 meters playspace was slightly too small and I ended after hitting my entrance wall with my bat, after which my overhead gentle becoming (2.5 meters up). I didn’t wish to danger damaging the Vive Tracker, so I referred to as an finish to my Tennis sport and put my bat away.

For gamers eager to get into ping pong or tennis, there appears to be an honest collection of older titles with Tracker assist to be used of sensible bats and rackets. General I completely loved the feeling of utilizing a tracked bat and will see myself shopping for the HTC Racket Set for a extra sturdy setup with two measurement choices.

Attaching it to a customized object – AIM Controller

After the frustration of not having the ability to purchase a gun for taking part in Arizona Sunshine, I discovered a PSVR AIM Controller on sale for simply £15 in my native gaming retailer. It appeared like a really perfect time to make my very own customized object. The AIM controller was a really cool peripheral constructed for Sony’s PSVR system. Utilizing an AIM in “Farpoint” was an incredible expertise, offering a tactile really feel and far improved controls with many various enter choices.  

(Picture by Rob Cole)

I downloaded a Vive Tracker render mannequin from HTC’s developer web site and purchased a digital mannequin of the AIM Controller from a digital mannequin storefront for $12. These belongings have been imported into CAD software program the place they have been aligned to create a hybrid of the 2.

(Picture by Rob Cole)

Within the bodily world, I utterly stripped down the AIM controller which turned out to be a easy shell predominantly empty however filled with enter parts at key areas. After eradicating two haptic motors, a chargeable battery, and quite a few flexes, it was able to accommodate the Vive Tracker.

(Picture by Rob Cole)

I’d already determined to mount the tracker on prime of the gun, to current probably the most seen points to the bottom stations for good monitoring. After shortly manufacturing a low-profile mounting plate from thermoplastic, I hooked up the tracker and took an correct measurement of its place to be used afterward.

After getting issues aligned and adjusting the render mannequin file utilizing the PC, it was time to rigorously obtain “the JSON” utilizing the lighthouse console. This command downloadconfig triggers the obtain of the JSON to your host PC.

The up to date JSON was uploaded to the Vive Tracker utilizing uploadconfig. Now when beginning SteamVR House, if pausing SteamVR, the AIM+Vive Tracker controller is seen as an alternative of the unique Vive Tracker render mannequin.

The subsequent step could be to attach a set off and buttons by means of the pogo pins, to see if it’s doable to get it totally working with the present model of SteamVR. It also needs to be doable to suit one of many haptic motors (ERM) when triggering haptic occasions to supply fundamental rumble suggestions for a sport like Arizona Sunshine. Nevertheless, I ran out of time earlier than this text was due, so I thought of doing this correctly as a enjoyable mission within the New Yr. 

Full physique monitoring setup utilized in VR Chat

Full Physique Monitoring (FBT) has turn out to be important for a lot of customers of the favored social media utility “VR Chat”. While different functions can be found, VR Chat is one of the best recognized and greatest populated with many customers in a position to have interaction utilizing desktop PC in addition to VR headsets.

(Picture by Rob Cole)

VR Chat has a thriving scene with folks utilizing Avatars appropriate with full physique monitoring, and there’s a rising neighborhood of creators making and promoting elaborate Avatars to the VR Chat neighborhood. There are additionally 1000’s of free Avatars out there so it’s fairly straightforward to search out one thing you just like the look of and take an Avatar for a take a look at drive.

VR Chat is completely usable with an everyday VR headset and controllers, however this solely offers “three factors” of monitoring (head, left hand, proper hand) to drive an Avatar.

Taking these three factors and making use of a software program mannequin permits a calculated place for the avatar arms, pelvis, and decrease limbs often called IK (inverse kinematics).

From developer Runevision: “Inverse kinematics (IK) is a option to routinely calculate the joint angles of e.g. a leg or arm primarily based on the place the finish effector (usually the foot or hand) ought to be. So you might specify that the hand of an individual ought to be at some particular place, and IK can then be used to calculate the joint angles of the shoulder and elbow as a way to make the hand be there.

Inverse kinematics want particular algorithms to “clear up” the issue of discovering the best joint angles. This isn’t trivial, particularly if a limb has greater than two segments. (A human leg would have two segments whereas a horse hind leg would have three.)”

Extra details about Inverse Kinematics might be discovered right here https://docs.unity3d.com/Manual/InverseKinematics.html

Nevertheless, IK tends to go wonky when customers transfer about particularly the hips, resulting in unusual uncomfortable sensations when the Avatar legs are getting into a special route to the person’s personal legs. Elbows are one other well-known drawback space, main many sport builders to make use of a “hand” or “glove” moderately than presenting a full arm to the person.

(Picture by Rob Cole)

For efficient Full Physique Monitoring in SteamVR, we are able to add a tracked hip/waist and tracked left and proper ft utilizing three SteamVR trackers. The picture above from Terrel Robust on the College of Washington was from an in depth research into IK and physique monitoring.

Including the Vive trackers offers three further factors of monitoring, offering a complete of six (together with HMD and two controllers) factors that may drive the avatar skeleton with management on every decrease limb and the waist. It’s doable so as to add further trackers in SteamVR, as much as 9 complete to additional tighten up skeletal management for the fullest physique monitoring expertise out there.

Tools used

(Picture by Rob Cole)
  • SteamVR-compatible headset (Valve Index)
  • SteamVR controllers (Valve Index)
  • VR succesful PC
  • SteamVR account (free)
  • VR Chat (free) on Steam
  • Three SteamVR Trackers (HTC Vive Tracker 3.0 with USB dongles)
  • USB cable extenders (if required)
  • Tracker straps (as required)

Strapping up: Waist

The Vive Trackers include 1/4” threaded screw mounts of their bases, however require mounting on straps or a belt to allow them to be hooked up to the physique.

After all, many various corporations make Vive-Tracker-compatible straps, belts, and gear, however being brief on time (couldn’t look forward to supply) I made a decision to make my very own. 

(Picture by Rob Cole)

The waist strap was constructed from a spare belt and a few thermoplastic I molded into an appropriate mount, after embedding a 1/4” bolt to let me screw the Tracker into place.

A protracted 3mm machine screw was used as a stabilizing pin to forestall the Tracker from attempting to rotate beneath motion. The rear of the plastic mount was confronted with industrial-grade velcro, I then added a thick foam pad to make it very comfy in opposition to the abdomen.

(Picture by Rob Cole)

The waist mount labored out nice and didn’t transfer round, really feel uncomfortable or trigger any monitoring points. The smaller and lighter Vive Tracker 3.0 helped on this respect with much less inertia when shortly transferring about. 

The sensation of getting a tracked pelvis actually opens up physique motion in VR… this was an analogous revelation to utilizing the free Decagear utility for Smartphones and Home windows PC which added tracked hip route in video games like Boneworks with nice success.

The Vive Tracker takes this to the following degree, monitoring the pelvis in 6DoF including a giant dimension to physique interplay and emotions of immersion. 

Strapping up: Ft

(Picture by Rob Cole)

For my ft, I made a decision to make easy shoe mounts with velcro straps and padding. The tracker was hooked up utilizing a 1/4” threaded becoming taken from some dwelling cinema speaker wall mounts, these fittings had flat plastic bottoms in order that they fitted snugly in opposition to the highest of the shoe.

Sporting footwear was greatest when it comes to stability, they let me strap the Trackers with out being excessively tight, the mounts have been steady and simple to get into in seconds. I used an extended velcro strap on every foot to wrap over the built-in strap, including one other layer of safety in opposition to undesirable motion.

(Picture by Rob Cole)

Regardless of performing some horrible dancing and plenty of random motion, the ft mounts by no means induced any bother with the Vive Trackers behaving very effectively throughout all my VR Chat periods. I additionally tried strapping them straight to my ft with out footwear, and discovered socks have been comfy however the Trackers tended to maneuver round slightly until strapped actually tight, so most popular utilizing footwear (these have very skinny soles so you possibly can really feel your tether as essential).

Getting Began: Avatar time

On launching VR Chat, you select an Avatar. There are a number of completely different free fashions out there with full physique monitoring assist. I attempted utilizing a number of completely different avatars together with a toy rabbit piloting a mech swimsuit, a red-eyed robotic, a suave fox, and a small furry in cyber gear (which has a bugs bunny model face beneath the visor).

(Picture by Rob Cole)

Every Avatar has a “really feel” to it when utilizing  FBT, and I discovered I actually appreciated utilizing the toy rabbit within the mech swimsuit as a result of it felt proper when it comes to scale and motion, while the toy rabbit driving the swimsuit made small physique and mouth actions; giving an odd sense of a puppet being puppeted.  

The small furry gave the worlds a special scale, making normal-sized avatars tower over my rabbit. I quickly observed a whole lot of small and really small Avatars in several worlds throughout my journey by means of VR Chat.

The suave fox was welcome in worlds inhabited by furries (seen within the image above carrying my consuming companion, a duck, don’t ask!) and the red-eyed robotic was actually exact for seeing the complete physique monitoring at work with its stripped-down skeleton ideally suited in that respect.

Calibration – VRChat

It’s very straightforward to calibrate full physique monitoring in VRChat: you simply open the person menu in sport, choose “FBT Calibration” after which undertake the “T” form (arms out at 90 levels).

(Picture by Rob Cole)

You must now discover your Avatar is totally calibrated to your monitoring setup. If you must recalibrate, simply use the menu. As soon as calibrated, you’ll all of a sudden discover that high-quality motion is tracked very precisely, together with one thing unprecedented… LEGS!!

“Hey Mark, we’ve received some legs over right here…”

Regardless of all of the latest hype concerning the Metawhatsit, and the way we don’t have tracked legs but in VR… effectively… I moved my actual legs and my Avatar legs instantly reacted, my mind almost fell out of my head with the sheer shock of all of it 🙂

After taking off my headset to recuperate, I checked on-line and plainly “tracked legs” have been doable since 2017 utilizing SteamVR, so does maybe Meta must double-check their knowledge? If they need an indication, they will let me know: I’ve a “SteamVR” room the place they will check out this superior new know-how 😉 

So the primary impression of getting legs was fairly placing, although not totally appreciated till standing in entrance of a “mirror” the place all of a sudden all of it made a direct sense and defined why folks spend all that cash on full-body monitoring setups.

A present limitation with single-focal size headsets is VAC (vergence lodging battle) the place your eyes discover it tough to resolve very shut objects in sharp focus.

Which means wanting instantly down at your avatar’s higher physique is considerably obscured by the difficulty of VAC making it more durable to focus clearly in your torso or higher arms, however when standing in entrance of the mirror the focal distance of the headset is as supposed making issues a lot sharper.

(Picture by Rob Cole)

Making minute actions which are exactly tracked in real-time driving your avatar provides a really sturdy connection within the mind, feeling akin to a gentle electrical shock, similar to after I first used the HTC Vive Pre in 2016. This was skilled each time I used Full Physique monitoring.

As many VR fans will sadly attest to, that electrical pleasure of being in VR throughout these early weeks or months quickly fades as you turn out to be accustomed to utilizing VR, making that fascinating feeling of sturdy presence much less usually attainted. Some customers report it turns into too apparent they’re observing two screens strapped to their heads, regardless of stereoscopic view and 6DoF monitoring. 

I assumed loads about this while utilizing Absolutely Physique Monitoring, and went again to Skarredghost’s latest interview with the legendary Jeremy Bailenson:

“There’s a joke I inform at cocktail events, and it’s not likely a joke as a result of it’s not humorous in any respect, however if you happen to’re going to ask me, what are the 5 most essential options that trigger presence in VR? My reply for you goes to be monitoring, monitoring, monitoring, monitoring, monitoring. I’ve nothing in opposition to decision… it’s all the time good to see a excessive res picture, and, in fact, area of view is essential, however if you happen to’re going to encourage presence, the factor that’s most essential is low latency, excessive body price, excessive accuracy of monitoring (which is basically essential)”

(Picture by Rob Cole)

I’ve learn many feedback from folks nonetheless fortunately utilizing the unique HTC Vive system for VR Chat, of their expertise having very correct Absolutely Physique Monitoring is far more essential than having the next decision headset. It’s additionally straightforward to select up used Vives at low costs, offering an affordable path to FBT (Full Physique Monitoring) for cash-strapped fans. Simply bear in mind that base station 1.0 and a pair of.0 know-how doesn’t all the time combine.

To reveal FBT from my very own perspective, I took my “toy rabbit within the mech swimsuit” avatar for a spin and made some completely different poses in entrance of an HQ mirror in VR Chat. On the identical time, images have been taken of what I used to be doing at precisely the identical time in the actual world (these have been flipped horizontally to match the mirror picture from VR Chat).

(Picture by Rob Cole)

Refined physique language appears to translate straight by means of the avatar which is thrilling stuff. The usage of full physique monitoring with sub-millimeter precision actually helps with immersion and experiencing sturdy emotions of presence once more.

With the ability to lie down, get up, roll over, karate kick, stand on one leg, and dance about felt actually liberating regardless of the tether. Dancing in a mirror alongside different FBT customers was actually vivid with all of the refined physique actions doing a really convincing job on my unconscious lizard mind.

(Picture by Rob Cole)

As quickly as you begin utilizing FBT usually you begin to discover different person Avatars and who has FBT or who’s utilizing a regular VR system with three factors of monitoring. The distinction within the physique language is evening and day, with the FBT customers very lifelike while commonplace customers look considerably stiff and unnatural. No judgment or elitism right here, simply an statement. I attempted utilizing VR Chat a few instances with out the Vive Trackers and one thing was positively lacking…

(Picture by Rob Cole)

Pricing

HTC Vive Tracker 3.0 can be found for a really useful retail value of £129 within the UK from completely different electronics retailers or from HTC instantly at https://www.vive.com with free delivery.

For some cause, they’re discovered to be rather less costly by means of HTC’s Amazon retailer at £127.50 together with free delivery and free returns. 

Different SteamVR tracker-style gadgets are additionally out there from Tundra Labs and Manus (aimed on the skilled market).

Conclusions

The second a part of this text was a whole lot of enjoyable, and a studying expertise about the ability of full physique monitoring to dramatically improve immersion resulting in stronger emotions of presence on a repeatable foundation, which for a long-term PCVR person was a revelation. I’m late to the FBT social gathering however higher late than by no means, and the Vive Tracker 3.0 is a helpful enchancment on the earlier era, so very straightforward to suggest. The software program on the SteamVR facet appears to have matured with good Tracker assist making it straightforward to arrange and handle. I had no points throughout weeks of use irrespective of how I moved or what I did.

I went into this anticipating to have a number of enjoyable constructing tracked objects and exploring completely different video games, however honestly the revelation of FBT meant extra time was spent in VR Chat the place it was straightforward to place FBT to good use. Different functions can be found, so search for FBT assist when testing new software program.

(Picture by Rob Cole)

There are sports activities video games that may work with the Vive Racket Sports activities set, and in case you are into tennis, ping-pong, or related sports activities then it ought to show effectively well worth the buy of a Vive Tracker and an appropriate bat. Whether or not weapons at present work I can’t verify nor deny, however I’ll attempt to construct out my tracked AIM gun within the New Yr, so I assume I’ll discover out then. 

As I discussed in my first article, the usage of FBT for functions like VR Chat appears to be driving wholesome gross sales of Vive Tracker (I met a whole lot of FBT customers) while peripherals are skinny on the bottom and never supported in lots of (if any) up to date video games. 

What concerning the prices?

It’s not a secret that it’s comparatively costly to arrange full physique monitoring, if doing it correctly with SteamVR and tracker-style gadgets.

It’s important to begin with a SteamVR system like Valve Index (£920) or Vive Professional (at present £719 on sale), then add three Vive Trackers (£387 with delivery) and a few Tracker straps (usually £40-70 for set), and naturally a VR succesful PC.

Are there alternate options?

For folks utilizing VR Techniques that aren’t SteamVR native (like Vive or Index) it’s doable so as to add base stations and SteamVR controllers after which mix the Quest/Pico/WMR and SteamVR playspaces utilizing an utility like Open VR Area Calibrator, which yow will discover at this hyperlink: https://github.com/pushrax/OpenVR-SpaceCalibrator. It’s described by the builders as:

“This helps you utilize tracked VR gadgets from one firm with another. It aligns a number of monitoring methods with a fast calibration step. It might not work on your setup, however there are various instances that work to a level, and a few work very effectively.”

Nevertheless, outcomes might fluctuate, with some customers reporting it’s nearly unusable while others point out it really works however common recalibration is required as the 2 monitoring methods are inclined to drift aside. For that reason, some customers will swap to a SteamVR headset (even an outdated Vive) to supply a dependable and hassle-free Absolutely Physique Monitoring answer.

There are different full-body monitoring methods in the marketplace, utilizing a number of IMU, exterior cameras, magnetic fields, or different monitoring know-how. They don’t are usually very correct, or undergo from drift, however do present some entry to physique monitoring at a extra reasonably priced value than going the bottom station route. Really a case of “you get what you pay for”…

Nevertheless, as esteemed boffin Jeremy Bailenson stated, “what are the 5 most essential options that trigger presence in VR? My reply for you goes to be monitoring, monitoring, monitoring, monitoring, monitoring.”.

From my expertise with the HTC Vive Tracker 3.0 throughout these months, they are going to definitely present what you want for FBT and sports activities gaming, offering that all-important feeling of presence.  Extremely really useful!

Thanks! Large because of HTC for offering the Vive Trackers and answering all my questions, because of Tony Skarredghost for internet hosting my article, and most of all because of you the reader.

(Header picture by Rob Cole)


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