Image courtesy Sony

Sony’s Mocap Device Lets ‘VRChat’ Users Unleash Their Inner Anime Girl

Once Japan-only, Now available in the US

By

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Jul 1, 2023

There are a few body tracking solutions on the market to help you on your quest to finally transform into a dancing anime girl, and Sony is now releasing its own previously Japan-only device in the US.

Mocopi, which gets its name from motion capture (mocap), was initially announced in late 2022, becoming available exclusively in Japan in early 2023. While a ton of vTubers worldwide already jumped the gun and ordered direct from Japan, now Sony is making it officially available in the US, priced at $450.

Mocopi comes with six small and lightweight inertial measurement unit (IMU) sensors that hook into a dedicated smartphone app (iOS and Android), letting you do full-body motion tracking both in and outside of VR.

Image courtesy Sony

And while Mocopi seems to be squarely targeting those would-be vTubers, another use case the company is trumpeting is undoubtably the device’s ability to give avatars better full-body tracking for things like VRChat. Yes, there’s a built-in VRChat integration, which means you can grab your Quest 2 or PC VR headset, hook up Mocopi to your extremities, and get dancing for all to see.

Like many such IMU-based tracking devices, positional drift is a real concern, although it seems Sony is pitching this more as a way to casually jump into body tracking and not get that 100 percent accuracy you’ll need when doing the [fill in a popular dance] on TikTok.

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Coming from Sony, you’d think there would be some sort of integration with PSVR 2, although that doesn’t seem to be a possibility. The company hasn’t mentioned any such integration since it initially launched in Japan in January.

Mocopi is already available for purchase, available exclusively from Sony for $450. Sony says Mocopi orders will ship to customers starting July 14th, 2023. Check out the Sony’s quick start guide below to get see just what you’re signing up for.

ViRGiN

cringe as F.
truly for degenerates.
- Jan Ciger
  
  But you comment was an intellectual masterpiece … Seriously, how old are you?
  - ViRGiN
    
    with profile picture likt his, it seems like you’re primary target customer.
    how many thousands of hours did you pour into vrchat as an anime girl with male-to-female voice changing software?
    two or three thousands hours?
    - Jan Ciger
      
      At least I don’t need to hide my face behind an anonymous avatar.
      
      Ad-hominem from an anonymous troll. Seems fitting.
      - ViRGiN
        
        Ah, yes, I’m guilty of protecting my identity.
        Why would ever someone want to do that!
  - Daniel Meyer
    
    ignore him. I am only a bit here on this site, and even I already know he is a troll.
    
    It is just sad, that such people bring nothing of value to the world.
    - ViRGiN
      
      more weebs to the rescue, how surprising!
  - disqus_o4N8KCTF90
    
    If its virgin. Click the three dots to the top right of his name and click block user. The sooner everybody does this the better. We will then be able to discuss article in an adult matter without his tantrums.
    - Daniel Meyer
      
      Okay, that was helpful, thanks. Is now on blocklist. It is always an improvment to block degenerates :)
      - disqus_o4N8KCTF90
        
        Definitely mate. He has been doing it for years. Spoiling the chat on every article with childish comments. He seriously needs to grow up.
    - Jistuce
      
      Nah, it just brings us closer to him registering a third account under the same name. I’ve blocked Virgin twice already.
- Andrew Jakobs
  
  So perfectly for you then….
  - ViRGiN
    
    yes, i’m always saying these nasty things to have higher chances of making it into first batch.
    the more people abandones the idea of buying it, the faster i’ll get mine.
  - disqus_o4N8KCTF90
    
    Is it virgin by any chance? I’ve got him blocked. I highly recommend it.
ale bro

From the video, the hip tracker seems like a weak point. Not every outfit has a waistband to clip it on. e.g. someone wearing a dress will not have a suitable place to clip the tracker on to. the kit should really come with a hip belt.
- Bunie
  
  Say what we’re really thinking, how are we supposed to use this while naked?
XRC

As legendary Stanford VR professor Jeremy Bailenson said in a recent interview with Skarredghost

“There’s a joke I tell at cocktail parties, and it’s not really a joke because it’s not funny at all, but if you’re going to ask me, what are the five most important features that cause presence in VR? My answer for you is going to be tracking, tracking, tracking, tracking, tracking. I’ve nothing against resolution… it’s always nice to see a high res image, and, of course, field of view is important, but if you’re going to inspire presence, the thing that’s most important is low latency, high frame rate, high accuracy of tracking (which is really important).”

IMU based tracking systems are affordable, but inherently inaccurate, which has unpleasant effect on presence as virtual and physical start to separate.
- Christian Schildwaechter
  
  Someone should/will combine purely IMU based trackers like Mocopi/SlimeVR with a simple camera based optical tracking like AprilTag. All VR tracking is IMU based, they usually just use an external fixed reference (Lighthouse/external camera/room recognized by internal cameras) to occasionally correct for the inherent inaccuracy due to IMU drift. All the external tracking options have a 10-100x higher latency than IMUs, but that’s fine when they are mostly used to automatically recalibrate the IMU based trackers.
  
  Mocopi requires a smartphone to connect the trackers and provide tracking data to a Quest/PC, so the simplest option would be to place that smartphone on a stand with the camera pointing towards the users, replace the black straps used to attach the sensors to arms, legs and head with straps featuring an easily recognizable pattern/fiducial markers/QR codes that will be visible most of the time, no matter towards where the user is turned. All phones listed as compatible are rather powerful, so adding low-frequency marker tracking should work fine.
  
  The open source AprilTag has > 30ms (camera only) latency due to the low webcam frame rate, but with Mocopi relying on rather fast and precise IMUs anyway, it might be more than enough to get a proper 6DoF position for each tracker strap every five seconds. Currently the sole problem would be the hip tracker, which would also need a patterned strap going around the waist, which would incidentally also solve the problem where to clip the sensor for those using VR, but not wearing pants. All Sony would need is to add the marker recognition to the Mocopi app, a feature that pretty much every computer vision library has already built-in, and update the straps with either printed ones or markers being placed on top. New straps shouldn’t add more than USD 10-20 on top, and with these additions their system could provide tracking stability similar to lighthouse, though with lower overall accuracy, but at least no longer requiring regular recalibration to prevent your arms and legs from drifting away.
- Guest
  
  So nice to hear from those not leeching off the internet and just parroting info. The Mocopi is horrible for anything with one leg or in a room with other BT devices plus it has a height limit of 190cm/6’3″
Garhert

Well, the idea is quite nice if it works well enough. But for $450 it should definitely have more use cases. At least the trackers for the legs could be used. Like grape stomping contests or (drop) kicking and stomping some zombies.
- Christian Schildwaechter
  
  It isn’t cheap. The very similar open source SlimeVR tracking system starts at USD 165 for five trackers with cheap/less precise IMUs. They support “extensions”, which are basically extra IMUs without a WiFi connected controller and battery that attach via cable to one of the existing trackers, giving you one more tracking position.
  
  USD 190 gets you 5 trackers +1 extension with more expensive/precise IMUs, USD 235 5 + 3, USD 295 7 + 3. And for USD 455, basically the same price as the six tracker Mocopi, you get an excessive 10 trackers + 6 extensions for a total of 16 tracked positions. Excessive, because most software only supports up to 11 tracked positions.
  
  I’d expect the Sony solution to be more polished and hassle-free, though initial comparisons to SlimeVR and HaritoraX Wireless (6 IMU trackers, USD 349) came with a lot of comments regarding stuttering and Mocopi urgently needing software updates. Mocopi hopefully at least ships right now, while the (next) HaritoraX is supposed to ship in August, and SlimeVR trackers ordered now won’t arrive before December.
  
  Comparisons between them are difficult, as a lot of people choose to built their own SlimeVR trackers, using cheaper IMUs, because the recommended ones are hard/expensive to come buy. The trackers consist of mostly an ESP8266 SoC (found in smart bulbs/plugs), an IMU, a LiPo battery and charging board plus switches, cables, cases, straps. The SlimeVR documentation provides a component calculator, and for 6 point (5 + 1) tracking you end up with USD ~84 plus shipping if you buy everything, less if you have a 3D printer, resistors, diodes and cables already lying around.
  
  That’s a less steep price for the limited use cases, but of course the glaring lack of VR grape stomping apps and zombie kicking and stomping games remains. That’s a chicken and egg problem, with very few people having access to FBT, there is little incentive to at least support it in games, and with no support in games, there is little reason to spent a lot of money on it. I still sort of hope that some Chinese company will offer SlimeVR based/compatible prebuilt trackers, which could drive the price for FBR down to around USD 100 for the large majority not interested in building their own. That’s a much more acceptable price level for a gadget of limited use, and the availability could/should motivate some developers to integrate support, if only to boast about it as a way to be noticed among all the other VR apps. And who knows, maybe grape stomping is the next Beat Saber.
TonyVT SkarredGhost

Let’s remember that to connect it to VRChat, the connection to transfer the full body data should go through a phone: Mocopi => Phone => VRChat