Perhaps you’ve seen digital out-of-home (OOH) media platform Firefly’s “taxi-top” screens in San Francisco, New York or Los Angeles and wondered, “how can they measure a moving target?” That was my question until I spoke with Firefly Chief Analytics Officer (and former Googler) Taylan Yildiz.

Yildiz says that not only are Firefly’s screens are measurable but that the company’s targeting and attribution are highly precise and reliable. He also talked to me about the dynamic geo-targeting capabilities of the moving digital screen that neither traditional OOH nor digital (but stationary) OOH screens can match.

Helping drivers earn more money

Firefly, which launched at the end of last year and has raised more than $50 million to date (with Google parent, Alphabet, as an investor), aims to put its digital screens on top of every cab, Uber or Lyft in America. (There are more than 2 million Uber and Lyft drivers in the U.S., not accounting for overlap.) The pitch to drivers is that they can make 20% more income, passively, by mounting the screen on top of their vehicles as they drive.

One of the tactics that has greatly aided traditional billboards and other OOH advertising has been the pairing of these fixed placements with mobile-location data to match media exposures with offline consumer behaviors. Location intelligence companies can determine the mobile ad IDs that were exposed to the OOH placement and then whether those devices showed up in a store, for example, a week later.

Screenwerk, about connecting the dots between digital media and real-world consumer behavior. He is also VP of Strategy and Insights for the Local Search Association. Follow him on Twitter or find him at Google .