IGES File Format Summary

Also Known As: Initial Graphics Exchange Specification

Type Vector and 3D
Colors NA
Compression Uncompressed
Maximum Image Size NA
Multiple Images Per File NA
Numerical Format NA
Originator IGES/PDES Organization
Platform All
Supporting Applications Many high-end CAD packages
See Also None

Neutral file format for CAD-related data.

IGES is used to share high-quality CAD data. It is not a proprietary format controlled by a private company. However, due to its complexity and difficulty, it is not commonly used by low-end CAD packages. Instead, it is most popular among expensive high-end CAD packages, such as those used in the automotive and aerospace industries.

IGES, the Initial Graphics Exchange Specification, is designed to exchange information between CAD systems and other vector-oriented applications. The standard is developed and maintained by the ANSI-accredited IGES/PDES Organization. The first version of IGES was adopted as American National Standard ANS Y14.26M-1981. Versions 3, 4 and the most recent version 5.2 were approved by ANSI as well.

For Further Information

Like other CAD formats, such as AutoCAD DXF, an IGES file can represent many different types of data, ranging from lines and arcs to the complex geometric solids, such as cylinders and cones known as "constructive solid geometry." IGES is much more complicated than DXF, though--perhaps four times as complex, judging by the sheer number of different geometrical entities. The IGES v4 specification encompasses more than 500 pages.

Because of the format's complexity, it is difficult to implement every possible operation and entity. Most IGES translators or IGES-importing programs describe exactly which IGES entities they support and which they ignore.

IGES has both an ASCII and a binary format. The ASCII format is line-oriented, because of its early origins on punched card systems. There is also a compressed ASCII format that eliminates some of the punch-card anachronisms. The binary format is much more compact than the ASCII version.

IGES is associated with NCGA (National Computer Graphics Association) as part of the U.S. Product Data Association (USPRO) and the IGES/PDES Organization (IGO). NCGA administers the National IGES User Group (NIUG), which provides access to information and is a place to exchange information on IGES.

For Further Information

For more information about NIUG and obtaining the IGES file format specification from NIUG, contact:

National Computer Graphics Association
2722 Merrilee Drive
Suite 3200
Fairfax, VA 22031
Voice: 703-698-9600

NCGA can also give you information about the National Institute for Standards and Technology (NIST) testing for IGES.

On the World Wide Web, see the NIST's pages at:


Most serious CAD packages provide tools for working with IGES data. For example, see the pages at:


and search their indexes for "IGES."

This page is taken from the Encyclopedia of Graphics File Formats and is licensed by O'Reilly under the Creative Common/Attribution license.

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