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Manual Reference Pages  -  G-IGES (1)

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g-iges - IGES Translator (BRL-CAD to IGES)



g-iges [-f | t | m] [-v] [-s] [-x flag1] [-X flag2] [-a abs_tol] [-r rel_tol] [-n norm_tol] [-o output_file_or_directory] database.g object(s)


g-iges converts the specified objects of the BRL-CAD database, database.g, to an IGES version 5.1 file, file.iges.

The following options are recognized


selects a BREP IGES file consisting of only Manifold Solid BREP Objects. All CSG solids in the specified objects are tessellated to produce facetted BREP objects, then the indicated Boolean operations are performed for each region. Individual regions are written to the IGES file as individual BREP objects. This procedure results in some approximations since curved surface solids, such as TGCs or ellipsoids, are approximated by flat facets. The accuracy of the tessellation may be controlled through the use of the -a, -r, -n options.

-a abs_tol

Sets the absolute tolerance (floating point value) for tessellation.

-r rel_tol

Sets the relative (to the size of the object) tolerance (floating point value) for tessellation.

-n norm_tol

Sets the normal tolerance (floating point value 0..1) for tessellation. This value is compared to the dot product of the normals to determine if the surfaces are within tolerance


indicates that an IGES file consisting of only trimmed NURBs should be created. The trimmed NURBs will all be planar NURBs, and they are the facets derived from the tessellation and Boolean evaluation as in the -f option. The file produced in this way is acceptable to the Pro/Engineer IGES import routine.


implies the -t option, and is used to produce multiple IGES files (one for each region converted). In this case the argument to the -o option should be a directory where the IGES files will accumulate.


requests debugging information


all facets in BREP objects should be output in the form of planar NURBs (Intergraph likes their IGES files this way).

-x flag1

set the librt debug flag (see raytrace.h for values)

-X flag2

set the librt debug flag (see nmg.h for values)

-o output_file_or_directory

Specifies the output file (or in the case of the -m) the output directory for the iges file(s).

-P num_cpus

Specifies the number of processors to use.

If neither the -f , -t , nor the -m options are selected, the default is a CSG IGES file. In this situation, all regions will be written to the IGES file as Boolean trees with all possible solids rep- resented by their IGES CSG equivalent. In cases where there is no IGES CSG equivalent, the BRL-CAD solid is tesellated (using the provided tolerances), and a BREP object is written for that solid.


g-iges -f -o sample.iges sample.g object1

This command will produce an IGES BREP output file, sample.iges, from object1 of the BRL-CAD database file sample.g.



The Initial Graphics Exchange Specification (IGES) Version 5.1, IGES/PDES Organization, September 1991.


Error messages are intended to be self-explanatory.




This software is Copyright (c) 1993-2013 by the United States Government as represented by U.S. Army Research Laboratory.


Reports of bugs or problems should be submitted via electronic mail to <>.

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BRL-CAD G-IGES (1) 04/04/2016

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