Because marker-based position tracking system is inexpensive and easy to use, it has the potential to make the system more feasible for homes or businesses and broaden the current suite of augmented reality (AR) techniques. To apply marker-based systems to homes or businesses, blending markers with environments naturally is important. Our innovative approach to marker-based 3D position tracking uses seamless patterns encrypted with positional data. Although users can obtain 3D positional data by processing marker images similar to many existing marker-based systems, our markers are designed with interior decoration in mind. That way they can be installed in walls, floors, or ceilings. Unlike existing systems whose fiducial markers were designed first and foremost to be processed by computers, ours are visually attractive. By integrating positional information within the interior design, our system enables users to enjoy the benefits of position tracking without being constantly aware of the system's presence. We developed a method for making patterns in which positional information is encrypted and a method for calculating the 3D position of a user by decoding those patterns. We then constructed a system using three patterns that were made by the proposed method and evaluated that system.