||This paper explains the three-dimensional representation procedure of one fragment of Milá house elevation designed by the architect Antoni Gaudí. The generation process of an architectonic virtual model constituted by free form surfaces like this, represents a paradigm of high level difficulty in CAD modeling. The main objective of our research has been not only construct a model that shows the complex form of its architecture, but also verify the performance of the different tools supported by computer aided design programs in the management of surface modeling.We obtained an accurate information of the real surface elevation with a photogrammetric survey using contour lines. The transformation of this kind of data in a three-dimensional model was not immediately Thus, we have had study different ways to generate the three-dimensional model solution. The process began with the construction of different surface models supported by analytic functions, but the obtained surfaces made with this system were deficient and not too much satisfactory. That's why, we use a polyhedron mesh surface method in order to improve these results.in spite of this methodology reductive performance, (compared with analytic function systems), the obtained surface demonstrated that this technique was the best way to satisfy the requirement of a free form surface previously established as we want to construct. From this point the principal problem was generate a surface defined by two-dimensional data, (contour lines), applying an automatic process sufficiently fast to compete with the analytic function systems.To satisfy the demand was necessary make complementary software to improve the process and allow more fluidity to resolve this typology of surfaces. We achieved this phase thanks to Joan Miquel Quilez collaboration and the constant dedication in the elaboration of complementary software to computer aided design. Finally, the introduction of render systems with lights, shadows, textures and reflected images, allowed show the studied elevation area of Milá house with more accuracy. Thus, the limits and contours of the finally surface were more evident and help us to known the properties of a non- materialized free form surface successfully.