This paper deals with edge detection and vertex characterization of 3D meshes. First, a new measure is introduced, the saliency degree, which provide directly the shape information of a vertex of the mesh without any curvature computation. The relationship between the saliency degree and the curvature is demonstrated for continuous and discontinuous 2D curves. Then, a description of the 3D operator is given. Finally, results on geometric and real objects are shown. The contributions of this work are the definition of a new 3D operator which is able to extract point characteristic on 3D low resolution mesh.