If you've ever waited on a subway platform, you're familiar with that woosh of air that comes through the tunnel prior to a train's arrival. Swedish ad agency Akestam Holst and production company Stopp produced an ad for a new line of hair care products that puts that phenomenon to good use.
The creative Swedes put ultrasonic sensors behind video screens on a subway platform in Stockholm. They then connected the sensors to the screen via a Raspberry Pi microcomputer.
The video screens showed a woman with long flowing hair. When the sensors detected the approaching train they triggered the video image to show the woman's hair flying around her face as if it were being blown by the wind from the tunnel. Simple, but effective. So effective, in fact, that the company left the ad for Apotek Hjärtat's Apolosophy products up for five days even though it had originally only planned it as a day-long stunt.
Take a look...