IGS

IGES (Initial Graphics Exchange Specification) is one of the earliest neutral CAD exchange formats, storing geometry as B-Rep entities such as NURBS surfaces, trimmed patches, and analytic curves. For decades it served as a standard bridge between CAD systems in the automotive and aerospace industries, and a vast amount of historical engineering data still circulates today in .iges or .igs files.

IGES is a surface-oriented exchange format: the solid topology of modern CAD is often flattened into independent trimmed surfaces, and it carries no materials, textures, or parametric assembly history. Starting in 1994, its role has been gradually taken over by STEP. When opening legacy files, note that independent surface entities may leave open gaps, and the format does not support textures. It is suitable for geometric review rather than appearance presentation.