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PDElib IGES Programming Interface

PDElib IGES Interoperabilty The IGES module of ITI Transcendata's comprehensive data exchange software library (PDElib) provides powerful IGES translation capabilities to your data exchange applications. Explore the wealth of features offered: full parsing and formatting, validation, entity manipulation, attribute handling, and much more!

What is IGES?

The Initial Graphics Exchange Specifications (IGES) defines a neutral data format that allows for the digital exchange of information among computer-aided design (CAD) systems.  CAD systems are in use today in increasing numbers for applications in all phases of the design, analysis, manufacture and testing of products.  Since it is common practice for a designer to use one supplier's CAD system and for the contractor and subcontractors use different systems, there is a need for

IGES provides a neutral definition and format for the exchange of specific data.  Using IGES, a user can exchange product data models in the form of wire frame or solid representations as well as surface representations.  Applications supported by IGES include traditional engineering drawings as well as models for analysis and/or various manufacturing functions.  In addition to the general specifications, IGES includes applications protocols in which the standard is interpreted to meet discipline specific requirements.

IGES as an American National Standard

Version 1.0 of the specification was adopted as an American National Standard (ANS Y14.26M-1981) in November of 1981.  Subsequent versions have followed as ANS specifications with version 5.2 approved and adopted by the American National Standards Institute (ANSI) in 1993.  The current version, IGES 5.3, was approved by ANSI under the new guidelines of the U.S. Product Data Association (US PRO) during September,1996.  Under the latest distribution agreements with ANSI, US PRO has obtained permission to distribute IGES 5.3 in both paper and digital (e.g., CD-ROM) formats.  The latest version of the IGES standard is designated ANS US PRO/IPO-10001996

Plans for future versions of IGES

Updates to the IGES specification are developed through the IGES project activities of the IGES/PDES Organization (IPO).  IGES version 6.0 is slated to be the next, and final, release of the standard.  As enhancements to STEP become available, members of the IGES project are focusing a significant portions of their efforts on the development of an IGES to STEP migration strategy.  Current plans call for the support of activities related to maintaining the existing IGES capabilities with all new requirements being forwarded for consideration in the appropriate parts of the STEP/PDES standards.


IGES Interface Highlights


IGES Parser/Formatter IGES Data Definition File (DDF) Geometry & Topology Mapping
The IGES ASCII File Parser (IAFP) and IGES ASCII File Formatter (IAFF) subsystems have been fine-tuned for high-performance reading and writing of IGES data. The parser performs rigorous  error checking for both syntactical and semantical errors while reading the  IGES file. A comprehensive ASCII DDF is used to describe the IGES entity data.  A compiler is included which generates the C structures and static declarations allowing for consistent access to IGES entity data after parsing. IGES geometry and topology data is conveniently mapped between the populated IGES memory model and corresponding neutral entity representations within PDElib Core (GDX subsystem).  Once in GDX, complex manipulations may be performed on the data.

IGES Validation System IGES Attribute Manager JAMA-IS Filtering Support
The IGES Entity Validation Manager (IEVM) subsystem allows for comprehensive  and controlled checking  and automated correction  for IGES entities on input. Over 500 checks are performed with nearly 300 potential corrections available. An Entity Attribute Manager subsystem is utilized by the IGES interface to maintain attribute information such  as: color, line-weight, line font, view, entity level, blank status, etc. "Parent" DE Attribute data may also be automatically applied to all applicable "Child" entities.  The Japan Automotive Manufacturers Association (JAMA) has specified a subset of IGES data (JAMA-IS) to be used within their industry.  Function calls are included to provide JAMA-IS compliant data.

Other Key Features


Start and Global Sections Backpointers IGES Constants Tolerances Processing Solids
The start and global sections are stored as entities in the model. They are automatically created and will always be locked in memory. The IGES file parser can automatically generate entity backpointer information if  desired. The include file iges_Interface.h has #defines for virtually all IGES constants. Tolerances are used for epsilon, max coordinate, and geometry conversions and approximations. Limited functionality exists for processing IGES manifold B-rep solids (186s)

Entity Mapping Entity Deletion DE, Property, and Associative Structures Implementer Defined Properties & Entities
IGES geometry entities may be manipulated within the PDElib Geometry Conversion Engine to achieve the best possible translation results between systems. Functions are available which intelligently delete the target entity,  its children, and fix any references by the parents of the target entity. Each entity has a DE, property and associative structure defined and available for access by an application. Functions are included to access implementer defined properties and entities explicitly.

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