How about that fourth screen? This growing media sector is projected to grow at an annual CAGR of 13.5 percent through 2013 with a total category take of $3.7 billion. But, trying to define what DOOH is and how to make it an effective part of any advertising campaign is still a work in progress. However, important strides are being made and this morning’s panel participants are active players across the DOOH ecosystem.

This panel was moderated by Rick Ducey, BIA/Kelsey’s Chief Strategy Officer, and our panel participants were Sonya Rosas, practice leader, DOOH for the Interpublic Emerging Media Lab; Stephen Randall, CEO of LocalModa; and Adam Bleibtreu, CEO of Retail Media Co., an owner of DOOH networks.

First some basic facts. DOOH is any combination of media assets that include digital billboards that rotate several ad messages per minute to place based media seen where people congregate from health clubs and taverns to elevators and airports. While the general outdoor market is heavily consolidated (three companies accumulate 85 percent of all dollars spent), the DOOH sector is not. It’s expected that many of the existing outdoor companies will be in the market to acquire DOOH assets as the growth in this part of the out of home sector is expected to outpace the general outdoor market ( billboards).

The panelists discussed the need for DOOH to be easier to plan and buy. There has been some improvement in the metrics used to measure the ROI of these media assets. However, there was a warning to marketers that all screens used in a campaign must be connected. The phone plays a critical interactive role in DOOH campaigns and allows the consumer to take part in the call to action on the screen. The flexibility of this new platform is quite attractive as messages can be changed on the fly to address different audiences.

Some of the new face recognition technology is allowing marketers to see who the audience is and how it changes at different times of the days. Messages can then be adapted so that there is relevance to what’s being displayed. This ability to allow the consumer to make an emotional attachment to the screen is a critical element in the success of the message. Location is also essential. Some venues work better than others (think gas pumps and elevators). Public places can make it harder to make DOOH work but it’s not impossible to do so. (Think Times Square).

The grocery stores are also great laboratories as new shopping carts can allow shoppers to enter their shopping lists onboard the cart. The cart is aware of where the cart is in the store and specific sales and promotional messages can be passed along to the consumer based on the shoppers’ profile and based on what’s on their list.

Taxis have also proven to be a good venue for DOOH. These units have been mostly limited to New York and Chicago but that’s soon to change. The GPS coordinates of these taxis allow messages to be delivered to the passenger that are based in the neighborhood of where the taxi happens to be located. These units are quite popular with advertisers and have sold out even in this difficult advertising environment.

There was also some discussion on the successful selling of these new digital and place based boards. One panelist believed that they made the right decision to partner with ABC to sell their inventory. The second sale is the hardest to make and managing the account is critical to the seller. CBS and NBC are also both in the digital out of home business with existing partnerships.

This sector is ripe for consolidation and the next 12-18 months should be interesting to watch as this new and vital advertising platform continues its impressive growth.