Wavelet-based blind watermarking of 3D models

Watermarking of 3D meshes has received a limited attention due to the di±culties encountered in extending the algo- rithms developed for 1D (audio) and 2D (images and video) signals to topological complex objects such as meshes. Other di±culties arise from the wide variety of attacks and manip- ulations 3D watermarks should be robust to. For this rea- son, most of the 3D watermarking algorithms proposed so far adopt a non-blind detection. In this paper we present a new blind watermarking algorithm for 3D meshes. In order to simultaneously achieve watermark imperceptibility and robustness a multiresolution framework is adopted. To do so we assume that host meshes are semi-regular ones, a prop- erty that permits to ¯rst perform a wavelet decomposition and then to embed the watermark at a suitable resolution level. Watermark detection is accomplished by computing the correlation between the watermark signal and the to- be-inspected mesh. Robustness against geometric transfor- mations such as rotation, translation and uniform scaling is achieved by embedding the watermark in a normalized version of the host mesh, obtained by means of Principal Component Analysis. Experimental results show the valid- ity of the proposed algorithm both in terms of imperceptibil- ity and robustness against a wide class of attacks including noise addition, smoothing and cropping.