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STEP

Table of Contents

Overview

ModelData.ModelReader can read STEP AP203, AP214 or AP242 files. ModelData.ModelWriter can write STEP AP242 files.

Scope

Import Export
  • B-Rep representations
  • assembly structure
  • graphical and semantic PMI
  • B-Rep representations
  • assembly structure
  • graphical and semantic PMI

Mapping

Import Mapping

Below tables show how STEP entities are mapped into MTK entities after import.

Product Structure

STEP Entity MTK Entity
product_definition One of:
next_assembly_usage_occurrence ModelData.Instance
item_defined_transformation Geom.Transformation

Topology

STEP Entity MTK Entity
manifold_solid_brep ModelData.SolidBody
brep_with_voids
shell_based_surface_model ModelData.SheetBody
face_based_surface_model
edge_based_wireframe_model ModelData.WireframeBody
geometric_curve_set
closed_shell ModelData.Shell
oriented_closed_shell
open_shell
advanced_face ModelData.Face
face_surface
curve_bounded_surface
face_bound ModelData.Wire
face_outer_bound
edge_loop
connected_edge_set
composite_curve
boundary_curve
outer_boundary_curve
edge_curve ModelData.Edge
oriented_edge
vertex_point ModelData.Vertex

Geometry

STEP Entity MTK Entity
Surfaces
b_spline_surface_with_knots Geom.BSplineSurface
rational_b_spline_surface
uniform_curve
quasi_uniform_curve
conical_surface Geom.ConicalSurface
cylindrical_surface Geom.CylindricalSurface
offset_surface Geom.OffsetSurface
plane Geom.Plane
rectangular_trimmed_surface Geom.Surface
spherical_surface Geom.SphericalSurface
surface_of_linear_extrusion Geom.SurfaceOfLinearExtrusion
surface_of_revolution Geom.SurfaceOfRevolution
toroidal_surface Geom.ToroidalSurface
Curves
b_spline_curve_with_knots Geom.BSplineCurve
Geom.BSplineCurve2d
rational_b_spline_curve
uniform_curve
quasi_uniform_curve
circle Geom.Circle
Geom.Circle2d
ellipse Geom.Ellipse
Geom.Ellipse2d
hyperbola Geom.Hyperbola
Geom.Hyperbola2d
line Geom.Line
Geom.Line2d
offset_curve Geom.OffsetCurve
Geom.OffsetCurve2d
parabola Geom.Parabola
Geom.Parabola2d
trimmed_curve Geom.Curve

Export Parameters

Export parameters are controlled by ModelData.ModelWriterParameters and applied using ModelData.ModelWriter.SetParameters() . STEP export uses the following parameters:

Parameter Default value Description
ModelData.ModelWriterParameters.WritePCurves false Writes parametric representations of edges on surfaces. Enabling this option provides additional data useful to some computer-aided design (CAD) systems, but may increase the output file size.
ModelData.ModelWriterParameters.WritePMI false Exports graphical and semantic PMI, subject to the limitations below.

Known Limitations

The following limitations apply to STEP export:

  • PMI.SavedView is ignored. PMI elements are exported without their saved view organization.
  • PMI.TextComponent is ignored. Text stored in this graphical component is not exported.
  • PMI.CurveOutline and PMI.CurveOutline2d are discretized and exported as polylines.
  • PMI.SurfaceFinishComponent is ignored.
  • Only the semantic attributes listed below are exported. Other semantic attributes are ignored.

Supported semantic attributes: