Overview of IGES in 3ds Max

The Initial Graphics Exchange Specification (IGES) is an ANSI standard that defines a neutral form for the exchange of information among dissimilar computer-aided design (CAD), computer-aided manufacturing (CAM), and computer visualization systems.

3ds Max implements the IGES standard for translating files between 3ds Max and IGES file formats used by the mechanical engineering and entertainment industries. Using the IGES import/export feature, you can read in and write out native NURBS data between 3ds Max and programs such as Mechanical Desktop release 3.0, Maya™, Pro/ENGINEER®, SOFTIMAGE®, CATIA®, and others. For complete details on the IGES standard, see The Initial Graphics Exchange Specification (IGES) Version 5.3.

What IGES Translates

The ideal file translation preserves the appearance and functionality of objects (called entities in IGES) contained in a file. This process has limits. You should be aware that some 3ds Max objects are not supported or not fully supported by IGES. Similarly, be aware that some IGES entities are not supported by 3ds Max. For example, you can't translate animation data and mapping coordinates, as these elements are not supported by IGES.

As with all translations, concepts that can be expressed succinctly in one language might not have exact equivalents in another language; conversely, concepts common to two languages might be expressed differently by each.

Even when the objects you translate don't have an equivalent in the target system, a one-time translation to or from IGES might not pose a serious problem. However, data loss can become a concern if you maintain objects that will be repeatedly translated in and out of different formats through IGES. By becoming familiar with the details of the systems and the IGES translators you use, you can learn to structure files to minimize information loss.

WarningThe conversion of objects during translation is not fully symmetrical. If you import an IGES file that you created by exporting to IGES, the resulting objects might not be identical to the original.

NURBS

When you import an IGES file into 3ds Max, IGES meshes are converted to NURBS surfaces, rather than to 3ds Max mesh objects. An IGES file with multiple meshes imports as a single NURBS model. Each IGES mesh is a surface sub-object within the model.

Each surface sub-object based on an IGES mesh is initially a rigid surface. To edit the surface and its CVs, you must first make the rigid surface independent. The following procedure explains how to do this.

Future Compatibility

The group that maintains and updates the IGES standard, the IGES/PDES (Product Data Exchange Standard) consortium, attempts to keep IGES upwardly compatible. It's likely that files generated by 3ds Max will be compatible with future versions of IGES.

Procedures

To make rigid imported NURBS surfaces independent:

Select the object.
Go to the Modify panel.
In the Modifier Stack rollout, choose Surface as the sub-object level.
Select the surface sub-object you want to edit.
In the Surface Common rollout, click Make Independent.
NoteMaking rigid imported NURBS surfaces independent can take a long time if there are complicated surfaces in the file, or if the file is large. Avoid selecting all surfaces and then clicking Make Independent. Rather, save your file immediately after successfully importing it, and then use Make Independent with care.