macOS Vision holds the GIL for the ~124 ms it takes to read a rail band, so the
tag pass decides the live frame rate: with 2 bands every 15 frames a walking
session fell to 1.7 results/s, and 1 band every 30 frames brings it back to 7.2
with tags still settling in a second or two. Measured, not guessed - the same
walk, same method (orb), only the OCR duty cycle changed.
The walk also gained a `pan` parameter (default 0.06, clamped 0.005-0.5) so a
demo can choose its pace: pan=0.02 sweeps a row over ~8 s, which reads like a
person rather than a time-lapse.
Demo configuration measured end to end on the walk (20 s, 1280x720, one client):
orb, pan=0.02, 1 band/30 frames -> 7.2 results/s, 178 labelled tracks, 21
distinct SKUs, first label 0.7 s, 3 readable price tags.
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
/v1/demo/plan + /v1/demo/frame give a demo the one thing a still image cannot:
motion. The virtual camera pans a shelf row left to right, steps up, and pans
back - a store employee sweeping a shelf - over a real shelf photo, ~1 ms per
frame, deterministic, and wrapping so an unattended demo loops. The client drives
only `step`, so the walk's speed follows whatever frame rate it can sustain.
Three real defects came out of measuring the walk rather than a still:
- Bands were keyed by on-screen position, so a walking camera minted a new key
every few pixels of pan and re-read the same shelf continuously. Keyed by row
now; OCR stops chasing the window.
- The classification budget was consumed by retries of products already leaving
the frame. Retries now skip anything near the edge, and a track gets 2 attempts.
- The pan advance was 0.22 of the window per step: a facing was in view for one
or two frames, so nothing could ever be classified (9 labelled tracks in 20 s).
0.06 keeps a product in view for about a second.
Measured on the walk (20 s, 1280x720 frames, one client): orb labels 296 tracks
across 21 SKUs with the first label at 0.2 s, while hybrid manages 13 tracks /
4 SKUs at 5.4 s - so the live default for a demo is the fast method, with hybrid
kept for tap-to-inspect.
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
