# Security Protection of 3D Models of Oblique Photography by Digital Watermarking and Data Encryption
## 7 Conclusions  
In response to the copyright ownership and privacy information leakage issues faced by 3 DMOP, a security protection strategy for 3 DMOP is proposed. The security protection strategy for 3 DMOP mainly consists of two aspects: (1) embedding of copyright informa  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Model**} & **Number of** & **Vertex** & **Number of** & **Texture** \\  & **Vertex** & **Coordinates** & **Texture** & **Coordinate** \\  & **Coordinates** & **Watermark** & **Coordinates** & **Watermark** \\ \hline M-1 & 409,363 & 54.738214 & 517,477 & 15.169614 \\ M-2 & 434,616 & 43.703921 & 544,407 & 9.550489 \\ M-3 & 306,074 & 29.185463 & 369,923 & 15.143082 \\ M-4 & 354,  
tion in 3D models. When embedding copyright information, vertex coordinates and texture coordinates of 3D models are selected as embedding features for embedding separately. Compared to traditional 3D model spatial watermarking algorithms, the vertex coordinate watermark embedding algorithm in this paper improves the robustness of the watermark algorithm by clustering point cloud data in the data preprocessing part to obtain clustering clusters and extracting feature points in the clustering clusters. After common attacks on 3D models, the copyright information can still be completely extracted; using texture coordinate information as an embedding feature is less common in related oblique photography 3D model watermarking algorithms. After embedding the texture coordinate watermark, it is less affected by common watermark attack methods, and the robustness and imperceptibility of the watermark algorithm are strong. Embedding copyright information in both watermark embedding features enables complete extraction of copyright information after one watermark embedding feature is attacked. (2) Encryption of texture information in 3D models. Encrypted texture information is evaluated using MSE and SSIM, both of which have high security. This method improves the current security protection scheme for 3 DMOP.  
In future work, we will further study and optimize image encryption algorithms to improve the efficiency of image encryption, solve the problem of texture coordinate watermarking being prone to extraction failure after 3 DMOP format conversion, and further enhance the robustness of watermarking algorithms.  
Conceptualization, Y.J. and Y.Q.; methodology, Y.Q., J.L. and Y.J.; software, Y.J.; validation, Y.J. and Y.Q.; formal analysis, Y.J.; investigation, Y.J.; resources, Y.Q.; data curation, Y.J. and C.M.; writing and original draft preparation, Y.J. and C.M.; writing--review and editing, Y.J. and Y.Q.; supervision, Y.Q.; project administration, Y.Q.; funding acquisition, Y.Q. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (Grant No. 42101433) and the Natural Science Foundation of Jiangsu Province (Grant No. BK20201100).  
Not applicable.  
Data Availability Statement: Data are available from the corresponding author upon request. The data are not publicly available due to privacy.  
We would like to express our sincere gratitude to the anonymous reviewers for their kind comments and suggestions for improving the manuscript.  
The authors declare no conflict of interest.