Using 3D QR code for marketing, EMart, the largest chain store in Korea, found that by noon, sales would drop sharply. In order to solve the sales problem at noon, they had to come up with an effective solution. This idea finally fell on the QR code, which not only solved the technological innovation, but also improved the performance. The company found that the minimum sales time is from noon 12 to afternoon 1, so it is necessary to make use of various existing conditions when improving. Smart EMart planner made a very interesting package for QR, and launched a special 3D QR code, which customers need to rely on the shadow generated by sunlight to appear. They placed a "3D QR code" device all over Seoul. At first glance, you will think that it is just a model with many square columns. However, every day from noon 12 to afternoon 1, due to the change of the direct angle of the sun, the shadows under these pillars gradually become complete QR codes. Consumers can only get EMart coupons by scanning the QR code at this time, which greatly increases the sales of supermarkets at lunch time.