Survey: 3D watermarking techniques

In today's world, 3D multimedia data is widely utilized in diverse fields such as military, medical, and remote sensing. The advancement of multimedia technologies, however, exposes 3D multimedia content to an increasing risk of malicious interventions. It has become highly essential to implement security measures ensuring the authenticity and copyright protection of 3D multimedia content. Watermarking is considered one of the most reliable and practical approaches for this purpose. This work provides an in-depth and up-todate overview of various 3D watermarking methods, covering different data forms, including 3D images, 3D videos, 3D meshes, point clouds, and NeRF. We have categorized these methods from multiple perspectives, comparing their respective advantages and disadvantages. The study also identifies attacks based on data type and discusses metrics for evaluating the methods according to their intended use and data type. We further present observations, research issues, challenges, and future directions for 3D watermarking. This includes strength factor optimization, copyright concerns related to 3D printed objects, detection and recovery of tampered areas, and watermarking in 4D (3D Dynamic) and NeRF domains.