Reading results

A completed session carries three things worth rendering: the measurements, the target ranges, and the annotated video.

Metrics

"metrics": [
  { "key": "cadence", "value_num": 176.4, "value_json": null },
  { "key": "knee_angle_series", "value_num": null, "value_json": { "…": "…" } }
]

Note

value_num is always SI — centimetres, metres per second, milliseconds, degrees. No imperial anywhere on the wire; convert at your presentation layer.

value_num is null when the metric is not a single number. Then value_json carries it, in one of three shapes:

• a time series — a value per frame or per rep, for charting
• a 2D trajectory — { kind: "trajectory", … }, an (x, y) path such as a bar path or a hip path
• a categorical reading — a label rather than a quantity

Any one session emits only the metrics its (activity, exercise) pair defines — usually 10 to 40 of the 620 keys that exist platform-wide. Do not assume a fixed set; iterate what you are given.

Human-readable labels, units and descriptions for every key come from the catalogue, not from the session payload. Fetch them once and cache.

Metric targets — the green zone

"metric_targets": [
  { "key": "cadence", "min_good": 165, "max_good": 185 }
]

This is the good range for this athlete, already resolved for their gender and body size. It is deliberately separate from the measurement, because the measurement is a fact and the target is a judgement that moves with who is being measured.

Render both. A cadence of 176 means nothing on its own; 176 inside a 165–185 band means “fine, stop worrying about it”.

Caution

With no attached athlete, targets fall back to population defaults — which the underlying tables themselves describe as biased toward male normative data. One of the better reasons to attach a Client.

The annotated video

analyzed_url is an MP4 with the skeleton, joint angles and phase markers drawn on. anonymized_url is the same thing with the face blurred, when the session was created with blur_face. thumbnail_url is a still.

The raw upload is never anonymised — only the analysed render is.

Before you show any of it

Check capture_findings first. A completed session whose footage the tracker could barely read still produces a full set of numbers, and they are not trustworthy. See the analysis lifecycle.