Abstract: In the process of 3-D model watermarking, emhedding watermark will make distortion on the 3-D model. Assessing the quality of 3-D watermarked model correctly can hchave as one of the principles of assessing 3-D watermarking scheme. In this paper, a quality assessment measure for the 3-D model was proposed. To compare with traditional quality assessment methods such as SNR ratio and Hausdorff, this method is more suitahle for 3D models. First, we calculated the roughness of the mesh model with the dihedrals which is the primitive of a 3D model. Second, we calculated the roughness of the watermarked model after watermarking. Last we calculated the increment of roughness between the original mesh and the watermarked mesh in order to assess the distortion made by watermarking. Moreover, the proposed method can estimate the distortion of watermarked mesh model made by various attacks.

Key words: 3-D model digital watermarking, Roughness, 3-D mesh, Watermarking scheme