A computer-implemented method for watermarking a 3D modeled object comprising the steps of: - providing at least one surface having a geometry and defined by a field of points of the surface and a field of normal vectors normal to the surface, the geometry of the surface having a shape and the field of normal vectors being a normal map with a lookup operator, the normal map being adapted for rendering of a 3D representation of the modeled object according to the field of points, wherein the rendering comprises computing a projection on the screen according to the field of points and shading the projection according to the normal vectors retrieved from the normal map; and then - watermarking the object by: ∘ performing a densification of the field of points and accordingly a densification of the field of normal vectors, wherein the densification of the field of points comprises performing subdivisions, and the densification of the field of normal vectors comprises creating new normal vectors by interpolating previous normal vectors, and ∘ modifying the field of points while keeping the field of normal vectors as it is, thereby allowing the traceability of the object, wherein the modifying of the field of points modifies the geometry of the surface thereby introducing a perturbation to the shape of the geometry of the surface. - providing at least one surface having a geometry and defined by a field of points of the surface and a field of normal vectors normal to the surface, the geometry of the surface having a shape and the field of normal vectors being a normal map with a lookup operator, the normal map being adapted for rendering of a 3D representation of the modeled object according to the field of points, wherein the rendering comprises computing a projection on the screen according to the field of points and shading the projection according to the normal vectors retrieved from the normal map; and then - watermarking the object by: ∘ performing a densification of the field of points and accordingly a densification of the field of normal vectors, wherein the densification of the field of points comprises performing subdivisions, and the densification of the field of normal vectors comprises creating new normal vectors by interpolating previous normal vectors, and ∘ modifying the field of points while keeping the field of normal vectors as it is, thereby allowing the traceability of the object, wherein the modifying of the field of points modifies the geometry of the surface thereby introducing a perturbation to the shape of the geometry of the surface. ∘ performing a densification of the field of points and accordingly a densification of the field of normal vectors, wherein the densification of the field of points comprises performing subdivisions, and the densification of the field of normal vectors comprises creating new normal vectors by interpolating previous normal vectors, and ∘ modifying the field of points while keeping the field of normal vectors as it is, thereby allowing the traceability of the object, wherein the modifying of the field of points modifies the geometry of the surface thereby introducing a perturbation to the shape of the geometry of the surface.