[Philip Lelyveld comment: this is a brilliant marketing tool.]

[SpringWise]

Korean Emart recently placed 3D QR code sculptures throughout the city of Seoul that could only be scanned between noon and 1 pm each day — consumers were given discounts at the store during those quiet shopping hours.

… Dubbed “Sunny Sale,” Emart’s effort involved setting up a series of what it calls “shadow” QR codes that depend on peak sunlight for proper viewing and were scannable only between 12 and 1 pm each day. Successfully scanning a code took consumers to a dedicated home page with special offers including a coupon worth USD 12. Purchases could then be made via smartphone for delivery direct to the consumer’s door.

See the full post and video here: http://www.springwise.com/retail/seoul-retailer-3d-qr-codes-sun-deliver-discounts-quiet-times/