Lesson 5 of 6 · 7 min read · intermediate
Digital out-of-home: billboards that bid
How digital billboards and screens are bought programmatically, who the players are, how audiences are estimated with multipliers, and how plays are verified.
The giant screen above a busy crossing in Tokyo, a digital poster in a Mumbai metro station, the rotating panel at a São Paulo bus stop: these are DOOH (digital out-of-home) screens. Many of them are now bought the same way as web ads, through auctions and DSPs, with ads that can change by time of day, weather or even live sports scores.
Traditional billboards are like renting a wall for a month and hoping people look. Programmatic DOOH is more like renting that wall for just the ten minutes when the office crowd walks past, and only when it is raining so your umbrella ad makes sense.
How programmatic DOOH works
- Screens join an SSPMedia owners connect their screens to a DOOH supply platform, which knows each screen's location, size, loop length and audience estimates.
- A slot comes upWhen a screen's loop reaches an available slot, it or its content system sends an ad request.
- Buyers bidDSPs bid, usually through deals, for that play based on location, time, venue type and audience data.
- The ad playsThe winning creative plays on the screen, often for 6 to 15 seconds.
- Proof of playThe screen's player logs that the ad actually ran; that log is the basis of billing.
The players
| Company | Role |
|---|---|
| Vistar Media | DOOH ad tech and marketplace; acquired by T-Mobile, completed in February 2025 |
| Broadsign | Content management and ad serving software used by many media owners, plus a programmatic platform |
| JCDecaux | One of the world's largest out-of-home media owners, with its VIOOH programmatic platform |
| Hivestack | Programmatic DOOH platform, acquired by Perion in 2023 |
| Local media owners | From Clear Channel and Outfront in the US to Times OOH in India, Eletromidia in Brazil and major rail networks in Japan |
Measuring an audience you cannot identify
A web ad reaches one browser. A billboard reaches everyone who glances at it. DOOH therefore counts an ad play and then estimates how many people were likely to see it, using an impression multiplier (also called audience per play).
| Input | Example |
|---|---|
| Ad plays | One play of a 10-second ad |
| Audience estimate | Footfall or traffic counts, adjusted for likelihood to notice the screen |
| Impression multiplier | Say 25 people per play at rush hour, 3 at midnight |
| Billed impressions | 1 play x 25 = 25 impressions |
Audience estimates come from bodies such as Geopath in the US and Route in the UK, mobile location data, transit ridership, cameras that count faces without identifying them, and traffic sensors. Outcome measurement often uses footfall attribution: comparing store visits among phones seen near a screen with those that were not. The IAB, the OAAA and others have published DOOH measurement guidance, and the OpenOOH venue taxonomy standardises how venues are described.
What makes DOOH creative different
A DOOH ad has no sound in most places, no click and only a few seconds of attention from someone walking or driving past. Good creative is bold and simple: one message, big type, a strong image. The programmatic twist is that the creative can react to conditions. A drinks brand can show a cold-drink ad only when the temperature passes 30°C in Chennai, a transit screen can show live departure times next to an airline ad, and a sports bar can promote the match while it is on. These triggers use outside data feeds, which is one reason DOOH is often bought through deals where buyer and media owner agree the rules in advance.
Verification and fraud risks
- Did it play? Proof-of-play logs come from the media owner's own system. Independent checks, including photos and third-party player monitoring, confirm the ad ran.
- Screens that do not exist: a screen ID can be declared in a request without a real screen behind it, similar to domain spoofing on the web.
- Screens that are off or broken: power cuts, blank displays and obstructed views still generate logs if nobody checks.
- Inflated multipliers: if audience estimates are exaggerated, every play is overbilled even though no bot is involved.
- Location data quality: footfall studies rely on mobile location signals that can include invalid traffic and spoofed GPS.
Key takeaways
- DOOH is digital screens in public places; programmatic DOOH sells individual plays through DSPs.
- Key players include Vistar Media (now T-Mobile), Broadsign, JCDecaux's VIOOH and Hivestack.
- Impressions are estimated with audience-per-play multipliers based on footfall and traffic data.
- Proof of play is the core billing record, so independent verification matters.
- Risks include non-existent or switched-off screens, inflated multipliers and poor location data.
Questions people ask
What is programmatic DOOH?
Programmatic DOOH is the automated buying of ad slots on digital out-of-home screens, such as billboards, transit displays and mall screens, using DSPs and SSPs. Instead of booking a screen for weeks, buyers can bid for specific plays by time, place and audience. Media owners connect screens to supply platforms, and proof-of-play logs confirm that each ad ran.
How are DOOH impressions counted?
DOOH platforms count each ad play, then multiply it by an estimate of how many people were likely to see it at that time and place. This audience-per-play multiplier comes from traffic counts, footfall data, transit ridership, mobile location data or sensors. Because the result is modelled rather than directly measured, buyers should ask how the estimate is built and verified.