Huge promotional posters installed in prominent places have been a long-standing staple of the advertising world thanks to their attention-grabbing scale and reach. In recent years this enduring format has been given a digital makeover, with Digital out-of-home (DOOH) combining the best of online and offline. Here we look at what DOOH offers advertisers, how DSPs can support them to achieve this, and how the channel is likely to develop from here.
In the beginning…
The roots of outdoor advertising can be seen in the civilizations of Ancient Egypt, Greece and Rome, where stone carvings and painted signs promoted events and goods for sale. Printing presses enabled the mass production of advertising bills and then large-format posters - the direct ancestors of the billboard as we now know it – and during the twentieth century, out-of-home (OOH) advertising cemented its position as a recognized medium the world over. Billboards proliferated, in some cases – such as New York’s Times Square, London’s Piccadilly Circus and Tokyo’s Shibuya Crossing - transcending their promotional status to become iconic landmarks in their own right, while three in Midwest America were the subject of a feature film in 2017.
The DOOH evolution
As its name conveys, Digital out-of-home (DOOH) is the digital progression of advertising traditionally found in public places. Taking many forms, the most popular fall roughly into three categories: digital billboards (known as large format); screens in shopping malls, airports, transport hubs, gyms (place-based media); and point-of-purchase ads inside a retail outlet (within-place media).
Located in high-traffic areas, digital screens are eye-catching and attention-grabbing; as implied by its ‘digital’ moniker, DOOH also introduces new attributes to outdoor advertising.
The most obvious is the speed of execution; no more giant rolls of paper, buckets of adhesives and cherry pickers - DOOH ads can be updated instantly. Digging deeper, digital enables programmatic media trading - and with that, game-changing, data-driven capabilities. Ad content can be targeted based on factors including the screen location, the demographics of the audience likely to be in the vicinity (students near a university, fitness enthusiasts near a gym, etc.), the time of day - and even the weather. A coffee brand might advertise hot drinks on a cold morning, for example, but switch to its iced offerings in the afternoon when temperatures rise.
Integration with mobile location data allows people to be retargeted across other devices, making DOOH a fully-fledged part of omnichannel advertising. Someone might see a DOOH ad for a new style of trainers and then get a discount code via a mobile ad when they are in the location of that brand’s retail outlet. These mobile-related touch points also deliver on the measurability front, enabling advertisers to access viewability scores for an ad, as well as attribute subsequent action (a store or website visit) to the campaign so that ROI can be determined.
The dynamic and interactive nature of DOOH throws open the doors for creativity. Often cited in this category is the British Airways multi-award winning #LookUp campaign, in which large digital screens in key sites under major flight paths in London linked to real-time flight data, enabling the destination, origin and flight number to be displayed at the moment a BA plane flew overhead.
All of this occurs within a brand-safe environment in which ads can’t be skipped or blocked.
Essentially, DOOH combines the best of offline - the reach and sheer unmissable presence of traditional billboards - with the smart responsiveness of digital, without compromising consumer privacy. It’s hardly surprising, therefore, that DOOH is increasingly a key element of advertising strategies. Brands that had perhaps moved away from static out-of-home advertising in favor of more interactive and data-driven channels introduced by digital can now put outdoor firmly back on the media plan.
The DSP opportunity
The DOOH market is forecast to reach $19.08 billion in 2025, with an annual growth rate of 6.79% between 2025 and 2030. Driven by factors including a growing number of screens, consumer expectations (particularly among younger, digitally native audiences), and ongoing advances in technology, these are significant numbers that convey a market on the up.
Global research shows that 27% of campaigns in the eighteen months to September 2024 were programmatic DOOH (prDOOH), a figure that is expected to rise to an average of 35% by early 2027. This presents a clear and immediate opportunity for demand-side platforms (DSPs) to expand their DOOH inventory by integrating with outdoor supply-side platforms (SSPs); as such they would be ideally placed to act as key enablers for brands increasing their DOOH budgets to realize the channel’s data-driven benefits and media owners looking to automate and monetize inventory.
RTB further streamlines transactions (with the IAB Tech Lab’s updates to OpenRTB standards providing technical resources for real-time bidding, thereby making programmatic access to DOOH inventory easier). They also enable all-important advanced targeting capabilities.
Inherent privacy compliance
Despite third-party cookies not being fully deprecated on Chrome, the industry is likely to continue to look to a future focused on protecting consumer privacy; DOOH - which is cookie-less by nature and privacy-safe by design - provides a solution.
First up, DOOH has never relied on third-party cookies, user IDs or personally identifiable information (PII), so does not have to reengineer how it operates. Instead, its focus is on deploying contextual signals (location, time of day, weather, local events, etc.) to be effective without intruding on personal data; advertisers don’t need to know who the viewer is - just where they are and what is happening around them - to serve relevant, timely messages.
Consumers are increasingly aware of their data privacy rights (75% say they won’t buy from organizations they don’t trust with their personal data), leading brands to become highly-privacy-conscious. DSPs proactively integrating DOOH into their offerings can position themselves as forward-thinking and future-ready partners.
Advertisers work with their DSP partners to select the screens where they want to appear, based on area, zones and venues - anonymized mobile data or foot traffic studies are used to map the audience profile of these screens, while timing adds another layer of precision. Between 11am and 2pm on weekdays, digital screens in urban areas with a high concentration of offices are ideal for outlets offering fast-food or takeaway lunch options, for example.
Events, such as sports games and concerts - or even traffic congestion - can also act as contextual triggers. Real-time environmental data provides another option, again completely anonymously, opening opportunities such as an outdoor clothing brand being able to deploy weather APIs to run its DOOH ads for waterproof jackets only when it’s raining. Aggregated and privacy compliant first-party data activation can also be deployed. A brand defines its key audience, and DSPs bid on spots where that audience over-indexes. Follow-up display, mobile or CTV ads can re-engage people later.
Ongoing innovation
In the digital landscape, outdoor advertising has had to play catch-up - but it has matured rapidly, thanks to ongoing advancements in technology.
Real-time bidding (RTB) enables dynamic bidding on impressions, underpinning time-based campaigns. As outlined above, live signals (weather updates, events, traffic congestion, etc.) can all be used to make ads highly relevant to where they are showing and when. And retail outlets can integrate inventory levels, such as showing the nearest stores with available products, with creatives tailored in real-time as stocks dwindle (or are replenished).
Measurement - an ongoing topic across the advertising sector - has also upped its game. DSPs can attribute store visits to a DOOH campaign by using aggregated footfall data, deploy mobile surveys to determine brand uplift, and track increases in site visits or purchases after someone has been exposed to a DOOH ad.
AI is - of course - unlocking many more possibilities. Dynamic Creative Optimization (DCO) determines - in real-time - which creative to show when and where, based on contextual signals and AI inputs. It can also act on external real-time feeds - breaking news, sports scores and social chatter, and so on.
As DOOH continues to prove its potential, more screens will appear, with these likely to be smarter - think interactive and sensor-based - to further engage users through recognizing gestures, adopting AR and using real-world gamification.
Privacy, accuracy and transparency concernDOOH is not immune to issues s
As noted above, measurement options have improved, but standards for metrics and attribution have yet to be agreed upon.
The industry-wide challenge of fragmentation is also alive and well, with the supply landscape still suffering from inconsistent formats and reporting standards across multiple media owners and screen specifications.
While DOOH offers huge potential for creativity, this is also a drawback in an environment in which screens vary widely, thereby requiring production teams to operate on a made-to-measure basis more often than is practical or cost-effective.
Clean, reliable data is an absolute pre-requisite if the full benefits of DOOH’s real-time capabilities are to be realized. However, integrating contextual and audience data into DSP workflows for DOOH buys can be complex.
The counterargument is that every advertising channel has thrown up similar hurdles, and the digital marketing sector has experience when it comes to finding solutions. The combination of industry bodies to tackle standardization, innovation to deliver technical solutions, and advertising’s can-do culture bode well for DOOH.
Working with BidSwitch
BidSwitch enables clients to take advantage of the latest DOOH technology and integrate the channel into their buying strategy.
BidSwitch ensures smooth trading by supporting all versions of OpenRTB (DOOH suppliers typically use version 2.x, while many buyers don’t, and need an entity to facilitate trading). And, with DOOH usually transacted via programmatic deals, BidSwitch enables DOOH buyers to trade via its Private Marketplace (PMP) Deals Center so that automation and efficiency are increased. BidSwitch also counteracts any delays between winning an auction and delivering the ad with its standard reporting.
Because impression attribution is less straightforward for DOOH than other online environments, an alternative approach is required to provide advertisers with a more accurate idea of the effectiveness of their (DOOH) ad. This is fulfilled by the DOOH-specific impression multiplier metric, which acts as a standard measurement methodology for the number of impressions delivered by a particular screen in a single ad play. BidSwitch supports all versions of the impression multiplier, regardless of the OpenRTB specifications adopted by a DSP.
To discuss how you can derive the full suite of benefits offered by today’s DOOH advertising, get in touch with BidSwitch today.