Unlike full encryption methods, for which the encryption does not preserve the internal structure of files, this paper presents an efficient format compliant selective encryption method for 3D object binary formats. The method encrypts selected bits of the 3D object geometry to visually protect the content without increasing the file size. Geometrical distortions are created in order to partially or fully protect the content , but they do not corrupt 3D scenes for preview purposes. As a function of the degradation level, we can obtain security from visual confidentiality to transparent encryption passing through sufficient encryption providing solutions for different application scenarios. Experimental results and analysis show the efficiency of the proposed method.