1. A process for modeling a surface representing an interface between two areas with different properties in a three-dimensional body, comprising the steps of: measuring to obtain a set of geometrical data, from said interface of said three-dimensional body, relating to the surface and associated with respective points on said surface; meshing the surface so that all said points are a subset of nodes of a mesh; storing at a specific memory address for each node of the mesh, the following data: first, second, and third coordinates, a number of satellite nodes, satellite node address data providing access to specific coordinates of said satellite nodes and consequently to satellite node related data relating thereto, and geometrical data associated with said each node of the mesh; for each node of the mesh, defining a local roughness index derived from a weighted sum of the coordinates of the node and of its satellites; defining a global roughness index obtained by summing the local roughness indices associated with the nodes, and a global violation index of said geometrical data, to thereby generate a sum of said global roughness index and said global violation index; fitting fitted coordinates of each node processed by an iterative method in which for each step of an iteration there is added a weighted combination of the coordinates of the node and of the satellites of said node and a combination of the geometrical data associated with said node, to thereby minimize said sum of the global roughness index and the global violation index; and creating a representation of the surface from the fitted coordinates of each node.