A method for computer-aided design of a modeled object having several faces, comprising a steps of identifying, for each of said faces of the object, at least another of said faces related to said face according to geometrical criteria, and marking such faces as connected; computing a plurality of points forming a tessellated representation of each of said faces; based on this tessellation, defining critical regions by determining and storing data representative of intersection between a three-dimensional geometrical figure and the face related to said face; determining whether intersections occur for each point of the tessellated representation of a face and for each face of the object; computing frontiers between points according to their respectively stored data and determines zones according to the determined frontiers; and, re-computing surfaces according to the determined zones.