QR codes on curved media facades: Two approaches for inverse distortion based on raytracing and image warping

Media facades and other public displays are a common sight in our everyday life. They can be found at various places, such as shopping malls or traffic hubs, e.g., the Times Square in New York City or Shibuya Crossing in Tokyo. Thanks to advances in technology, media facades are not bound to plane, rectangular shapes. Thus, many media facades are curved to increase their visual appearance or to better harmonize with the building behind. One example of such a curved media facade is the “Medienfassade” in the city of Münster. The shown content, however, is visually distorted due to the facade's concave shape. That visual distortion may cause problems for certain types of content, i.e., QR codes, that may thus not be scanned with mobile apps. Since QR codes became popular in recent years, it appears desirable to display these codes on curved media facades, too. Thus, we propose two preprocessing approaches to compensate for the visual distortions of the curved media facade. An in-situ evaluation showed that both approaches can be used to “rectify” the distorted QR codes and let them be scanned successfully.