Reference Formats
IGES
One of the earliest neutral CAD interchange formats, published by the US National Bureau of Standards in 1980 to move geometric and drafting data between incompatible CAD systems, later largely superseded by STEP.
Extension
.igs
Full name
Initial Graphics Exchange Specification
Introduced
March 1980, first published by the US National Bureau of Standards as NBSIR 80-1978
Vendor
US National Bureau of Standards (with Boeing, General Electric, and the US Air Force, Army, Navy, and NASA)
What is inside the container
IGES encodes CAD geometry as wireframe curves, trimmed surfaces, and (in later revisions) some solid representations, along with drafting annotations, organized as fixed-width ASCII records — a structure that reflects its 1980 origin, well before modern boundary-representation solid modeling was standard. It has no material, texture, or animation concept, and its surface representation is generally considered less robust than STEP's for complex solids, which is why most CAD vendors and standards bodies now recommend STEP for new interchange work while retaining IGES support mainly for legacy compatibility.
How to open it
For archives
IGES should be treated in a DAM as a legacy interchange format for CAD data predating the 1990s standardization on STEP, valuable primarily for older engineering archives, aerospace/defense legacy drawings, or older tooling records where STEP wasn't yet available or standard. Because IGES's surface representation is less robust for complex solids than STEP's, any active reuse of an archived IGES asset should be validated carefully after import — geometry gaps or surface stitching errors are a known risk. When both are available for the same historical part, retain the IGES as the original submission record but prefer converting to STEP for any ongoing engineering work, since STEP is more reliably supported by current CAD tools.
IGES was formalized in March 1980 by the US National Bureau of Standards (now NIST), published as NBSIR 80-1978 under the title “Digital Representation for Communication of Product Definition Data.” Its development was coordinated under contract to the US Air Force, Army, Navy, and NASA, with Boeing and General Electric playing major roles in the technical work — a reflection of just how badly the aerospace and defense industries needed a working way to move CAD drawings between the incompatible proprietary systems different contractors used.
As an ANSI standard since 1980, IGES became foundational infrastructure for CAD interchange through the 1980s and 1990s across automotive, aerospace, and shipbuilding, encoding curves, trimmed surfaces, and drafting annotations in a fixed-width ASCII record structure typical of that era’s data formats. Its surface and solid modeling capabilities, however, predate modern boundary-representation techniques, and as the industry’s needs grew more demanding, IGES’s limitations in reliably transferring complex solids became a recognized weakness — one of the direct motivations for developing STEP (ISO 10303) starting in 1984.
In DAM terms, IGES today is chiefly encountered in older engineering archives — legacy aerospace, defense, and automotive drawing collections from the 1980s through 2000s — rather than as an active production format. A DAM holding IGES assets should preserve them as historical records of the original submission, while flagging that any modern reuse likely needs conversion to STEP, and that the conversion should be checked for surface gaps or stitching issues that are a known risk when re-importing older IGES geometry.
Frequently asked
Why does a DAM still encounter IGES files given STEP is the modern standard?
IGES was the dominant CAD interchange format from 1980 through the 1990s, so legacy aerospace, automotive, and defense engineering archives commonly hold historical drawings and parts only available in IGES.
Is IGES still recommended for new CAD interchange work?
No — most CAD vendors and standards bodies now recommend STEP for new interchange because IGES's surface representation is less robust for complex solids, and STEP has effectively superseded it for active production use.
What kind of geometry can IGES actually represent?
Wireframe curves, trimmed surfaces, and some solid representations in later revisions, along with drafting annotations — but its solid-modeling capabilities predate modern boundary-representation techniques used by STEP and native CAD formats.
Should a DAM convert archived IGES files to STEP?
For active reuse, generally yes, since STEP is more reliably supported by current CAD tools — but the original IGES should be retained as the historical record of the original engineering submission.
What's a common risk when re-importing an old IGES file today?
Surface gaps or stitching errors are a known issue, since IGES's older surface representation methods don't always translate cleanly into modern CAD systems' boundary-representation solid modeling.
Who originally developed the IGES standard, and why?
The US National Bureau of Standards, working under contract with the US Air Force, Army, Navy, and NASA, with Boeing and General Electric doing major technical work — driven by the need to move CAD data between incompatible contractor systems.
Does IGES carry any material, color, or texture data useful for visualization?
No — like STEP, IGES is a geometry and drafting-annotation format with no material or texture concept, so any DAM preview of an IGES asset shows plain geometry, not a finished-appearance render.
How old is the IGES format compared to other CAD interchange formats in a DAM?
It's one of the oldest, published in March 1980 — predating STEP (developed from 1984) by several years, and predating STL (1987) as well, making it among the earliest formal CAD interchange standards still occasionally found in DAM archives.
Sources
- IGES was formalized in an early specification published by the US National Bureau of Standards in March 1980 as NBSIR 80-1978 checked 2026-08-07 — CAD Exchanger — IGES file format and extensions
- IGES development was coordinated under contract to the Air Force, Army, Navy, and NASA, with Boeing and General Electric playing major roles checked 2026-08-07 — Wikipedia — IGES