Viewability Beacon

A viewability beacon is a tracking pixel that fires only when an impression meets the viewability threshold defined by the Media Rating Council (MRC). The standard MRC video threshold is 50% of pixels viewable for 2 contiguous seconds — for a creative this is met, a viewability beacon fires; if not, only the raw impression pixel fires. Viewability beacons let DSPs and verification vendors bill / report on the viewable-impression subset.

Viewability beacons are typically wired through OMID's "impression" measurement event, which itself is gated by the OM SDK's geometry checks. The verification script subscribes to OM SDK events and fires its own beacon when geometry + duration cross the MRC threshold. The DSP sees the difference between raw and viewable impressions in its reporting and bills accordingly.

On DOOH, the MRC threshold isn't directly applicable — pixel-viewability is binary on a fullscreen ad slot. The DOOH viewability beacon instead fires when (a) the playout completed AND (b) audience-on-screen was greater than zero AND (c) attention crossed a threshold (where measured). Trillboards' viewability beacon fires at slot completion only when the on-device sensing SDK reports at least one face with medium-or-better attention during the playout.

Buyers should treat the viewability beacon firing as the actual billable event for attention-based campaigns, not the raw impression.