Because they will impact so many areas, copyright issues will inevitably arise as Threedimensional (3D) printing printing expands into the content industry. However, 3D printing introduces many copyright infringement issues for digital 3D objects because the object data can be directly printed, and distributed both online and physically. New distribution scenarios not previously considered also pose new content security problems. This paper reviews intellectual property protection issues and solutions in the 3D printing environment. We summarize various requirements not previously considered in the literature, defining infringement issues for new technology scenarios and requirements. We then analyze existing copyright security technology coverage according to those scenarios and various other aspects, and present the pros and cons of each technology and future research directions. The presented scenarios and reviews will provide significant benefits for the future development of reliable technologies that protect 3D printing intellectual property.
We also propose a robust and blind watermarking scheme that is able to protect content not only when the 3D model is shared in the digital world, but also when the 3D digital content is converted to analog content by 3D printing. First, we base our proposed watermark on a component that is unchanging to the printing direction for robustness against the printing process. The printing artifacts, instead of being regarded as severe distortion, are treated as a template that provides orientation information to the watermark detector. To achieve this, we also propose a blind estimation algorithm for the printing direction that starts from an analysis of the layering artifact. Using the results from a proposed estimator, the watermark from the printed-and-scanned model is synchronized with the original orientation. The results of our tests with various 3D mesh models and attacks, we experimentally verified that the proposed method does not lose embedded patterns during the 3D print-scan process, especially with low-cost printers. Moreover, our method provides a new solution for estimating the printing direction that will be useful in a variety of fields.