Localised without markers. The building could not be modified, so the corridor was photographed densely and processed into a 3-D feature map; at runtime the device estimates full 6-DoF pose by matching live camera frames against it.

Why that corridor is the hard case. Sparse texture that repeats — every bay looks like the next. Pose locks onto the wrong bay, or drifts, and the overlay slides off the wall. The work was in deciding when to trust a match and when to discard it.

Gas side. Two supplies, regulated delivery and valve control on a repeating cycle, phase-locked to what the viewer sees. Holding a steady rhythm is a matter of valve response, line volume and settling time — the commanded profile and the delivered profile are not the same curve.

Stated plainly. This is gas handling and flow fault-finding at atmospheric pressure. It is not vacuum or plasma process experience, and is not offered as such.

The real problem is threading. Blender's Python API is not thread-safe — call bpy from the socket's worker thread and the process dies, sometimes several operations later. The server accepts on a daemon thread but never touches the scene there: scripts go onto a lock-guarded queue that a bpy.app.timers callback drains on the main thread. That one indirection is the whole design.

Why build it. The same reason I instrument anything — describe the scene once and have it constructed repeatably, rather than rebuilding it by hand every time I change my mind.