The article considers the issue of studying the deviation of geometric parameters of a curved surface and a facet surface approximating it. The approximating surface was constructed by triangulation. To obtain adequate results when approximating a surface, it is necessary that the geometric parameters of the approximated surface differ minimally from the parameters of the faceted surface. One of the most important geometric parameters of a surface is its normal at a given point. The deviation of the normals of the given and approximating surfaces significantly affects the calculation error.

Keywords: curved surface, faceted surface, normal to the surface, linear frame, tinted image, plane compartment

In article the algorithm of construction of development not linear surfaces is de-scribed. The algorithm is realised on technology ObjectARX for AutoCAD. It has allowed to integrate algorithm in AutoCAD. The developed algorithms can be used in various technical problems where there is a necessity of construction of development of surfaces.

Keywords: nonlinear surface, surface development, triangulation method