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IGES Converter

Table of Contents

Overview

IGES_Reader can read files compliant with the IGES format up to version 5.3. IGES_Writer can write files compliant with the IGES format version 5.3.

The IGES converter can support Trimmed Surfaces (IGES type 144), Bounded Surfaces (IGES type 143) and Solid entities (IGES type 186).

Scope

Import Export
  • B-Rep representations
  • assembly structure
  • names
  • user-defined properties
  • colors
  • layers
  • B-Rep representations
  • assembly structure
  • names
  • user-defined properties
  • colors
  • layers

Mapping

Import Mapping

Below tables shows how IGES entities are mapped into CAD Exchanger entities after import.

Product Structure

IGES Entity Type IGES Entity Name CAD Exchanger Entity Note
308 Subfigure Definition One of:
408 Singular Subfigure Instance One of:
402 Group One of:
Flat list of roots ModelData_Part IGES allows single topology and geometry entities to be model roots. In this case they are grouped into ModelData_Bodies, which forms one ModelData_BRepRepresentation.
124 Transformation Matrix ModelData_Transformation

Topology

IGES Entity Type IGES Entity Name CAD Exchanger Entity
186 ManifoldSolid ModelData_Body
with type equal to ModelData_BT_Solid
514 Shell ModelData_Shell
108 Plane ModelData_Face
143 Bounded Surface
144 Trimmed Surface
510 Face
141 Boundary ModelData_Wire
142 Curve On Surface
508 Loop
504 Edge List Array of ModelData_Edge
502 Vertex List Array of ModelData_Vertex

Geometry

IGES Entity Type IGES Entity Name CAD Exchanger Entity
Surfaces
114 Parametric Spline Surface ModelData_BSplineSurface
118 Ruled Surface
128 BSpline Surface
120 Surface Of Revolution ModelData_SurfaceOfRevolution
122 Tabulated Cylinder ModelData_SurfaceOfLinearExtrusion
140 Offset Surface ModelData_OffsetSurface
190 Plane Surface ModelData_Plane
192 Cylindrical Surface ModelData_CylindricalSurface
194 Conical Surface ModelData_ConicalSurface
196 Spherical Surface ModelData_SphericalSurface
198 Toroidal Surface ModelData_ToroidalSurface
Curves
100 Circular Arc ModelData_Circle
ModelData_Circle2d
104 Conic Arc ModelData_Ellipse
ModelData_Ellipse2d
110 Line ModelData_Line
ModelData_Line2d
112 Parametric Spline Curve ModelData_BSplineCurve
ModelData_BSplineCurve2d
126 BSpline Curve
130 Offset Curve ModelData_OffsetCurve
ModelData_OffsetCurve2d

IGES geometry entities can be roots of the model or directly referenced by Subfigure Definition. In such cases they will be wrapped with the appropriate topology entity, ModelData_Face for surfaces and ModelData_Edge for curves.

Export Mapping

Below tables shows how CAD Exchanger entities are mapped into IGES entities after export.

Product Structure

CAD Exchanger Entity IGES Entity Name IGES Entity Type
ModelData_Assembly Subfigure Definition 308
ModelData_Part
ModelData_Instance Singular Subfigure Instance 408
ModelData_Transformation Transformation Matrix 124

Topology

CAD Exchanger Entity IGES Entity Name IGES Entity Type
ModelData_BT_Solid Solid 186
ModelData_Shell Shell 514
ModelData_Face Face 510
Bounded Surface 143
ModelData_Wire Boundary 141
Loop 508
Array of ModelData_Edge Edge List 504
Array of ModelData_Vertex Vertex List 502

Geometry

CAD Exchanger Entity IGES Entity Name IGES Entity Type
Surfaces
ModelData_BSplineSurface B-Spline Surface 128
ModelData_SurfaceOfRevolution Surface Of Revolution 120
ModelData_SurfaceOfLinearExtrusion Tabulated Cylinder 122
ModelData_OffsetSurface Offset Surface 140
ModelData_Plane Plane Surface 190
ModelData_CylindricalSurface Cylindrical Surface 192
Surface Of Revolution 120
ModelData_ConicalSurface Conical Surface 194
Surface Of Revolution 120
ModelData_SphericalSurface Spherical Surface 196
Surface Of Revolution 120
ModelData_ToroidalSurface Toroidal Surface 198
Surface Of Revolution 120
Curves
ModelData_Circle
ModelData_Circle2d 		Circular Arc 100
ModelData_Ellipse
ModelData_Ellipse2d 		Conic Arc 104
ModelData_Line
ModelData_Line2d 		Line 110
ModelData_BSplineCurve
ModelData_BSplineCurve2d 		BSpline Curve 126
ModelData_OffsetCurve
ModelData_OffsetCurve2d 		Offset Curve 130

Parameters

Importer Parameters

The IGES import parameters are controlled by IGES_ReaderParameters. The following table contains a list of parameters for IGES import:

Parameter Default value Description
SkipBlank() false Specifies whether the IGES reader should skip (if true) or convert (if false) IGES entities which have a blank flag in the IGES file. Conventions of using the blank flag in the IGES file are determined by the application creating the IGES file. For instance, it may be assigned to objects which have been used during creation of the main 3D model (e.g. various working planes, contours, etc).
SurfaceCurveMode() Auto Specifies which curves' representation is used to construct resulting ModelData_Edges during Boundary (type 141) and Curve On Surface (type 142) conversion.
  • Use3d - use 3D curve representation
  • Use2d - use 2D curve representation
  • Auto - the most appropriate representation is selected automatically based on source entity flags and data correctness

Exporter Parameters

The IGES export parameters are controlled by IGES_WriterParameters. The following table contains a list of parameters for IGES export:

Parameter Default value Description
WriteMode() MSBO Specifies the preferred format of topological entities:
  • MSBO - use Manifold Solid B-Rep (type 186) when writing solid bodies, i.e. preserve connectivity information. Sheet bodies are written without connectivity information to improve compatibility with receiving systems.
  • BoundedSurfaces - use Bounded Surfaces (type 143) when writing solid bodies, i.e. lose connectivity information. "BoundedSurfaces" mode should only be used if the target CAD application does not support MSBO entities (which should be extremely rare if ever).
OriginatingSystem() "Unspecified" See Base_WriterParameters::OriginatingSystem().