Nonio C is a program for modeling large topographic and cartographic surveys using triangles, contour lines, slope charts, color shading, sections, and three-dimentional views. Terrain is modeled using a method of triangulation, a valuable alternative to methods based on the generation of an orthogonal grid, which does not often correspond well to real-life conditions. Two surfaces can be modeled simultaneously, allowing the comparison of the original terrain with the modified or of two different project phases. Points data may be inserted using the keyboard, a graphic tablet, field survey, or ASCII file. The model is created either automatically or by imposing breaklines interactively with the mouse, recreating as closely as possible a representation of the actual terrain. Contour lines are drawn automatically. | 
