We present a contribution to the "reverse engineering" process through a method for the extraction of characteristic edges from a digitized part. The edge determination is realized step by step by fitting locally a surface, which presents a discontinuity. To avoid long process, this fitting is started only in areas with important curvatures. These areas are automatically detected with a prior paraboloid fitting.This approach enables to split the initial digitized point cloud along the edges. Each "elementary" cloud given by the process is the digitized representation of a basic surface. Such surfaces could be easier rebuilt than the initial global surface, by means of an implicit or a parametric representation. Our partition process is a first step to find CAD representation of a digitized part.