Qualisys Motion Capture & Ground Truth

Scope

Ground-truth motion capture subsystem and its software integration path into experiments.

Deployed Facts

• Qualisys setup docs define QDS as DHCP/network configurator for camera systems.
• QTM setup workflow includes locate-system, camera ordering, and calibration routines.
• Calibration requires consistent L-frame/wand process and periodic recalibration after camera movement.
• Python SDK docs show 6DoF streaming and QTM client-control workflow.
• Local integration script connects to Qualisys host over Techtile network and stores sampled positions.
• Techtile positioner library is used to extract tracked-body position from Qualisys.

Position Extraction Code

• Repository: https://github.com/techtile-by-dramco/positioner
• Purpose: retrieve Qualisys tracked-body position for experiments.
• Data path:
  • backend="direct": connects to QTM (qtm_rt), streams 6DoF frames, and returns averaged x/y/z (meters) and rotation matrix.
  • backend="zmq": subscribes to streamed position updates over ZeroMQ.
• Runtime note: the client expects a .env with QUALYSIS_KEY for QTM control access.

Interfaces

• Network: dedicated camera interface + host interface for control/streaming.
• Software: QTM + Python SDK (qtm / qtm_rt) integration.
• Experiment pipeline: position/rotation feed used as reference or labels.

Constraints and Risks

• Camera movement invalidates calibration products.
• Local script and install text include secrets and keys; these are redacted from docs output.
• Stream consumers depend on matching rigid-body naming and QTM project configuration.

Depends On

• Stable network path between QTM host and stream consumers.
• Physical camera placement and calibrated capture volume.

Provides To

• Ground-truth 6DoF trajectories for DAQ/RF/acoustic validation.

Critical Paths

• QDS interface assignment and DHCP handling before QTM discovery.
• QTM client-control and password settings before Python SDK streaming.