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WITNESS · Physical security sensing

Cameras, embeddings, matches, alerts.

Four steps. No black boxes. No "AI does it" hand-waving. Below is the actual pipeline, the actual model family, the actual residency story. If a step doesn't match what the camera estate in your building can support, we'd rather know now than during a pilot.

  1. 01

    Cameras

    Connect the cameras you already have

    Hikvision, Axis, Hanwha, Mobotix, generic ONVIF — any RTSP-speaking camera. We don't audio-record. We don't replace your VMS. We tap the same stream Milestone or Genetec is already on, read-only. Setup is a 4-line config per camera and a single firewall rule.

    No on-prem appliance. No proprietary cameras. No rip-and-replace.

  2. 02

    Embeddings

    Compute a vector per detection

    At the LHR edge node, the stream runs through a person-detection model (YOLO v8 family) into a re-identification model (OSNet variant). Output: a 512-dimensional float vector per detected person, per frame. The raw frame is held in a rolling 30-second buffer for operator playback, then discarded.

    Vector store is UK region only. Raw frames never leave the edge.

  3. 03

    Match

    Match across cameras within a window

    When a new vector arrives, we search against the recent embedding history (the operator sets the window — typically 5 to 45 minutes). Match threshold is cosine similarity > 0.78 by default, configurable per camera. Matches surface as 'this person, seen on camera B at 14:23, was also seen on camera A at 14:18.'

    Vectors expire after 14 days. No identity store. No name.

  4. 04

    Alert

    Alert the duty officer — not the whole building

    Operators see a thumbnail strip, the camera IDs, the timestamps, and the similarity score. No name. No 'who this person is'. The decision — escort to lift, intervene at door, call the police — stays with the human. We do the watching; they do the deciding.

    Webhook + dashboard. Optional Slack / Teams / Pagerduty fan-out.

A single frame. Four hops.

Camera RTSP · on-site stream LHR edge YOLO v8 · OSNet 512-d vector Embedding store UK · 14-day expiry match Alert duty officer
Single frame, four hops, ~120ms end-to-end on a 1080p RTSP feed. Raw frames never leave the LHR edge node.

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