CAD standard and translator

In order for CAD applications to run across systems from various vendors, four main formats facilitate this data exchange: IGES (Initial Graphics Exchange Specification), STEP (Standard for the Exchange of Product Model Data), DXF (Drawing Exchange Format), and ACIS (American Committee for Inter-operable Systems)

IGES is an ANSI standard for the digital representation and exchange of information between CAD/CAM systems. A 2-D geometry and 3-D constructive solid geometry (CSG) can be translated into IGES format. New versions of IGES also support boundary representation (B-rep) solid modeling capabilities. Common translators (IGES-in and IGES-out) function available in the IGES library.

STEP is an international standard. It provides one natural format that can apply to CAD data throughout the life cycle of a product. STEP offers features and benefits that are absent from IGES. STEP is a collection of standards. The user can pull out an IGES specification and get all the data required in one document. STEP can also transfer B-rep solids between CAD systems. STEP differs from IGES in how it defines data. In IGES, the user pulls out the specification, reads it, and implements what it says. In STEP, the implementor takes the definition and moves it through a special compiler that then delivers the code. This process assures that there is no ambiguous understanding of data among implementors.

DXF, developed by Autodesk, Inc. for AutoCAD software, is the de facto standard for exchanging CAD/CAM data on a PC-based system. Only 2-D drawing information can be converted into DXF, either in ASCII or in binary format.

The ACTS modeling function N a set of software algorithms used for creating solid-modeling packages. Software developers license ACTS routines from the developer Spatial Technology Corp. to simplify the task of writing new solid modelers. The key benefit of this approach is that models created using software based on ACTS should run unchanged with other brands of ACTS-based modelers. This eliminates the need to use IGES translators for transferring model data back and forth among applications. ACIS-based packages are commercially available for CAD/CAM and FEA software packages.

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