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Scene Analysis Triggers

The Scene Analysis Triggers feature lets you define triggers via metadata coming from Axis Scene Description, and react whenever an object crosses a line or enters/leaves a area.

Live preview and overlays

The central card shows the live view component. An overlay layer sits on top of the video and renders:

  • polygonal area triggers (green outlines) and direction markers for lines so you can double-check the crossing direction.
  • bounding boxes for every metadata observation, including colored corners and text that summarizes the class, score, line name, and area names.
  • line segments (dashed strokes when editing) that you can drag to change the start/end points and direction (enter, exit, or both).

Use the Add area trigger and Add line trigger buttons below the stream to drop new shapes. Click the pencil/delete/tag icons for each control bubble to edit the polygon or assign a label. The small dialog that pops up is the same one used for names anywhere else in Flow—only letters, digits, spaces, and underscores are allowed.

Filtering the metadata feed

The form on the left lets you tune the metadata that actually ends up in the zone:

  • Metadata Channel: Choose which metadata channel (1–4) to listen to.
  • Score filtering: Toggle the minimum-score filter and slide the threshold (0–1). Objects below the threshold are still visible but are marked in grey and will not trigger area/line colors.
  • Class filtering: Restrict the stream to a preset list (Human, Car, Truck, Bus, LicensePlate). You can check multiple classes at once.

Geometry helpers

  • Use the area or line handles to drag vertices (left click) or delete them (right click). Holding the pointer inside an area lets you move the whole area.
  • When no points exist, clicking on the overlay creates a default square around the cursor and immediately enters edit mode, so you can Add area trigger and draw in one flow.
  • Direction markers annotate each configured line, plus the overlay controls let you show/hide the area/line helpers (Hide Areas & Lines) or toggle the metadata bounding boxes (Hide Bounding Boxes). Turning off the geometry hides the handles but keeps the definitions alive.