| In recent years,the frequent occurrence of privacy leaks has aroused people’s attention to information security.As a supplement to encryption technology,information hiding hides secret data in multimedia products and transmits it silently,which is considered as a new way to solve the problem of information security.Compared with image and audio,the 3D model possess larger embedding capacity,and the 3D information hiding based on it can transmit more secret data.It also possess the functions of protecting 3D model copyright and annotation.In this thesis,the research and improvement of 3D information hiding in the spatial domain are carried out.The main work is as follows:(1)A vertex-synchronized 3D point cloud information hiding algorithm based on projection sampling is proposed,which improves the problem of unstable vertex synchronization under the premise of ensuring a short synchronization time of the algorithm.The algorithm first uses principal component analysis and normalization to construct the affine invariant space of the point cloud model,then expands all vertices on the XOY plane,projects them vertically into the grid,and controls the number of sampled vertices by adjusting the resolution of the projection surface.Finally,the sampling points are read according to the rules to synchronize the vertices.In the embedding stage,the secret data is embedded in the Z-axis coordinate value and color of the vertex at the same time,and the X and Y-axis coordinate values are not changed,which ensures the stability of vertex synchronization while large-capacity embedding is performed.The experimental results show that this blind extraction method has large embedding capacity,good imperceptibility,short time consumption,and can resist many common attacks.(2)A distortion-free 3D mesh information hiding algorithm based on surface element rearrangement is proposed,which solves the problem that existing algorithms cannot take into account both distortion-free and blind extraction.The algorithm first uses the Logistic chaotic map to select the embedding mode,and then embeds the secret data by rearranging the triangular surface elements through different embedding mode rules.The receiver can blindly extract the secret data according to the corresponding extraction mode rules.The experimental results show that the algorithm has no distortion,high security and strong robustness,and is suitable for situations where the three-dimensional carrier model cannot be modified,such as military,medical and other fields. |
