目的 随着数字化、智能化的3D打印、3D扫描技术的快速发展，传统制造业流水线上的产品都可被方便快捷的复制、生产时，版权问题已成为了3D打印时代一个日益突出且无法回避的问题。近年来如何对3D打印模型进行有效的版权标注和保护引起了研究者的关注，涌现了一些针对3D打印模型的版权保护方法，但算法的有效性和检测率仍需要进一步提高。为了全面反映3D打印模型版权保护研究现状和最新进展，本文对国内外公开发表的主要文献进行梳理和分析。方法 在广泛文献调研的基础上，立足于3D打印模型版权保护的基本框架，描述了3D打印模型文件，并详细阐述3D打印模型攻击类型，分析了3D打印和扫描过程对模型的影响。然后，根据3D打印模型版权保护策略的技术特征，对相关技术进行了分类，描述了每类方法的基本框架，并详细阐述了相关技术特征。最后，根据相关文献对3D打印模型数字水印算法进行了性能分析，主要从与传统网格水印算法的性能分析比较和抗3D打印-扫描攻击的性能比较2方面进行阐述。结果 由于3D产品模型即有数字化模型也有实体模型，同时3D打印是三维数据从数字模型到实体打印模型的过程，而3D扫描过程则把实体模型转换到数字扫描模型，这2类转换过程涉及到多次不均匀的采样与量化，是一个非常复杂的过程。而已有的三维模型数字水印算法主要侧重于对单一的数字模态模型的版权保护，忽视了实体模态下的产品模型的版权保护。同时，也未考虑3D打印输出过程的自身特性(即打印的分辨率、层厚度及光滑度，阶梯分层效果等)，以及3D扫描精度对模型数据造成的几何失真和畸变攻击。因此，传统的3D网格模型水印策略无法直接有效应用于3D打印模型。3D打印模型版权保护相关技术可以分为基于物理特性和基于数字水印的2类方法。基于物理特性的3D模型版权保护技术，能对3D打印后的模型嵌入有效的具有一定隐蔽性的版权标识，但该类技术在提取微结构体等信息时需要借助一些专用设备，不具有普适性。基于数字水印的方法，既能实现传统的数字模态下的相似性变换、剪切、噪声、细分、量化、光顺等攻击，又能有效抵抗3D模型的数/模等模态转换攻击，并且高精度的3D打印机和扫描仪能有效提高水印的检测率。结论 3D打印产品是设计者和生产企业的智慧和心血的结晶，包含知识产权。随着3D打印在工业领域的广泛应用，3D打印模型版权保护有着广阔的应用前景和研究价值，但针对目前3D打印模型的版权保护的检测和评估机制存在一些局限性还需进一步深入研究，需要构建统一3D打印模型测试库和3D打印模型水印评测体系等。
Research Progress on Copyright ProtectionTechnology of 3D Printing Model
Feng xiaoqing,Li li,Wang jilin,Dong keming,Liu yanan,Yan surong(School of Computer,Hangzhou Dianzi University;School of Information and Engineering,Zhejiang University of Finance and Economics,Hangzhou;School of Dongfang,Zhejiang University of Finance and Economics,Haining)
Objective With the rapid evolution of 3D printing and 3D scanning technology, products on the traditional manufacturing line can be easily and quickly copied, copyright issues have become an unavoidable and increasingly prominent problem in the 3D printing era. Trough 3D printing-scanning technology, users can quickly and easily copy and produce 3D models. The copyright protection problems become increasingly serious. In recent years, how to effectively protect the copyright of 3D printing models is causing more and more attention from the researchers. There are some copyright protection methods for 3D printing models have proposed, but the effectiveness and detection rate of the algorithms still need to be further improved. In order to fully reflect the research status and the latest development of copyright protection of 3D printing models, this paper focuses on the main literature published at home and abroad for comprehensive analysis. Method On the basis of extensive literature research, based on the basic framework of copyright protection of 3D printing model, the 3D printing model file is represented in detail. And the 3D printing model attack type is elaborated. Furthermore, the influence of 3D printing and scanning process on the model is analyzed. Then, according to the technical characteristics of the copyright protection strategy of 3D printing model, the related technologies are classified. The basic framework of each type of method and related technical features are described. Finally, according to some related references, the performance analysis of 3D printing model digital watermarking is carried out. It is mainly discussed from two aspects, mainly from the performance comparison of traditional grid watermarking algorithm and the performance comparison of 3D printing-scanning attack. Result The 3D product model has both a digital model and a solid model. At the same time, the 3D printing is a process of converting a digital model to a physical model, and a physical model is transformed to a digital scanning model during a scanning process. These processes involve multiple uneven sampling and quantization and they are very complicated processes. The existing 3D model digital watermarking algorithm mainly focuses on the copyright protection of a single digital modal model, ignoring the copyright protection of the product model under the physical mode. At the same time, the 3D printing characteristics (i.e., print resolution, layer thickness and smoothness, step layering effect, etc.) and the geometric distortion caused by 3D scanning are not considered. Therefore, the traditional 3D mesh model watermarking strategy cannot be directly applied to the 3D printing model. According to the technical characteristics of the 3D printing model copyright protection strategy, the related technology is divided into two categories: physical characteristics method and digital watermark. The copyright protection technology based on physical characteristics can embed effective copyrighted logos for 3D printed models. However, this kind of technology needs some special equipment when extracting micro-structure information and it has no universality. Methods based on the digital watermarking can not only resist against attacks of similarity transformation, cutting, noise, subdivision, quantization, smoothing in the traditional digital domain, but also effectively resist the modal transition attack of the 3D model. And the high-precision of 3D printers and scanners can effectively improve the detection rate of watermarks. Conclusion 3D printing products are the crystallization of wisdom and hard work of manufacturers and designers, and contain huge intellectual property rights. With the extensive penetration of 3D printing into the industrial field, copyright protection of 3D printing models has potential application and research value. However, there are some limitations in the detection and evaluation mechanism of the copyright protection of the current 3D printing model. Further research is needed. It is necessary to construct a unified 3D printing model test library and a 3D printing model watermark evaluation system.