Tiling is the obvious technique of layering a grid over the territory of interest, and defining location by squares on the grid.

Take a retail store, a restaurant, a stadium; draw a perimeter around it 100 yards, a mile , then define location as being within that perimeter.

The geo-tagging which is often embedded in photos and other content uploaded to social networks, combined with keyword and hashtag searches, permit tracking social activity within a tile or radius, or along a vector, of interest.

Beyond the banal--"She's near our store, let's send a discount coupon to her phone"--are more creative approaches, some of which may turn out to be fruitful.

Imaging knowing, whether at the segment or individual level, who is looking at your "real" world advertising, as well as where they've been, where they're going, and what their recent browsing and social behavior has been.

Cloud-based inventory permits precise targeting of ads in a physical but digitally connected environment .

The text above is a summary, you can read full article here.