What is CGM?

CGM is an ANSI/ISO 8632 standard format since 1987 for representing 2-D technical illustrations. Developed by experts working under the auspices of ISO and ANSI, and was designed specifically as a common format for the platform-independent interchange and storage of raster (bitmap), vector and text data. CGM files typically contain vector, raster and text data.

CGM offers the advantage of small file size and resolution independence, while not being tied to a specific software package or hardware platform. CGM was adapted by the US Department of Defense as one of the CALS initiative standards.

CGM is defined in ISO 8632:1992 together with Amendments 1 and 2, and specifies a two-dimensional data interchange standard which allows graphical data to be stored and exchanged among graphics devices, applications, and computer systems in a device-independent manner.

CGM format has a structure that can represent vector graphics (e.g., polylines, ellipses, NURBS), raster graphics, and text. Although initially a vector graphics format, it has been extended in three upwardly compatible extensions to include raster capabilities and provides a very useful format for combined raster and vector images.

A metafile is a collection of elements. These elements may be the geometric components of the picture, such as polyline or polygon. They may be details of the appearance of these components, such as line colour. They may be information to the interpreter about how to interpret a particular metafile or a particular picture. The CGM standard specifies which elements are allowed to occur in which positions in a metafile.

Application Profiles

Model Profile specified in CGM Amendment 1
CALS profile specified in MIL-D-28003A
ATA profile ATA Specification 2100 Graphics Exchange
CGM PIP Web profile for use in Web applications (an OASIS Standard)

CGM ATA Profile

ATA Specification 2200, GREXCHANGE has been developed for technical documentation of the manufacture and operation of commercial airplanes. The profile supports the binary and clear text encodings at the CGM Version 4 functionality level. It is appropriate for the exchange of technical manuals, publishing applications, and visualization. A second profile, ATA Specification 2200, IGEXCHANGE provides for the transfer of intelligence associated with graphical data. This profiles supports the application structuring defined in CGM Amendment 2.