Precision Controllable Reversible Watermarking Algorithm for Oblique Photography 3D Models

The existing reversible watermarking algorithms for the oblique photography 3D model can only restore the original model or not, which fails to meet the diverse needs of different users. Therefore, we propose a reversible watermarking algorithm for the oblique photography 3D model in this paper, aiming to achieve controlled model error recovery. Firstly, according to its global stability, the feature points of the oblique photography 3D model are extracted by utilizing the mean angle between vertex normals. Secondly, a mapping relationship is established based on the ratio of distances between feature points and non-feature points. Then, the vertices are grouped, with each group consisting of one feature point corresponding to several non-feature points. Finally, a spherical coordinate system is constructed with the feature point as the origin of each group. The watermark information is embedded by modifying the radius of the coordinate system. In the process of extracting the watermark, we extracted the watermark from different positions within the radius. This method recovers the model by obtaining different radii so that the method can achieve controlled data error. In addition, the experimental results have demonstrated that this algorithm can achieve controlled recovery of model error and exhibits good robustness against attacks such as translation, rotation, cropping, and simplification.