A Multi-ring Color Fiducial System and A Rule-Based Detection Method for Scalable Fiducial-tracking Augmented Reality

In Augmented Reality (AR), a user can see a virtual world as well as a real world. To avoid the registration problem between the virtual world and the real world, the user’s pose in both worlds should be exactly the same. Fiducial tracking AR is an attractive approach to the registration problem, but most of the developed fiducial tracking AR systems have very limited tracking ranges and require carefully prepared environments, especially lighting conditions. To provide for wide views and detailed views in large-scale applications, an AR system should have a scalable tracking capability under varying light condition. In this paper, we propose multi-ring color fiducial systems and a lightinvariant fiducial detection method for scalable fiducial tracking AR systems. We analyze the optimal ring width, and develop formulas to obtain the optimal fiducial set with system specific inputs. We present a light-invariant circular fiducial detection method that uses relations among fiducials and their backgrounds for segmenting regions of an image. Our work provides a simple and convenient way to achieve wide-area tracking for AR.