Motion Capture for “Room Scale” Virtual Reality

Motion Capture for “Room Scale” Virtual Reality

Criffin is working with clients by providing consulting and services in serious gaming and simulations. While for some solutions our locomotion system RUNPAD is ideal, for others room scale systems must be implemented.

Optical vs Wireless

When we talk technology, we must keep track on what we talk about. In room scale tracking Motion Capture (mocap) consists of two important aspects:

  1. Skeletal animation
  2. Positioning inside the room

Optical tracking is the lowest latency solution while IMU (sensor type) positioning has its’ challenges. Both technologies are good but some are better for certain use cases than others.

Criffin has been researching and developing VR technologies for over three years.

Optical Tracking

Optical tracking uses IR filters to see only tracking markers. Based on the positions of the markers the positions and distances are calculated by the server. One very high quality provider in this space is OptiTrack.

Plusses:

  • Very low latency
  • Great precision

Minuses:

  • Absolutely stationary system
  • User must be always in the sight of camera(s)
  • Dark corners (one user covers up another) may be a problem
  • In case of using walls for the VR simulation, all cameras must be placed all around the walls; planning can not be changed easily
  • Complexity in putting suits on
  • With classic systems durability is low – markers get easily damaged and must be constantly changed

Wireless Tracking

Wireless tracking in this context involves two technologies: IMU tracking and wireless positioning. Our IMU skeletal tracking system uses all wireless sensors and tracking works by analysing angular data coming from the sensors. Based on smart sensor fusion algorithms full motion capture works. However, that system isn’t able to detect user’s location in the room. For that we have tested, developed and integrated bits and pieces and achieved +/- 10 cm precision with zero latency.

Hereafter a short clip where Criffin’s Lead Engineer Jaanus Kalde is testing technology with developers from PlayersTracking on a football field:

 

Plusses:

  • IMU tracking very durable
  • Great UX in terms of wearing
  • Very durable
  • No dark corners
  • Not stationary, light walls won’t matter (planning of simulation room can easily be changed)
  • compared to optical systems affordable

Minuses:

  • Latency bigger than optical systems (24ms max, not noticeable)
  • Slight error rate compared to optical systems (not noticeable by user)
  • +/- 10cm error in room positioning (not dangerous in terms of walls & objects, but enough to not allow detailed physical user interaction)

Verdict

The truth is every system has it’s use. For room scale VR motion capture for consumer use (e.g. VR theme parks, etc.) I’d still suggest the latter of the two, however also fusion of the two technologies is a viable solution.

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