EXPRESS Definition
EXPRESS-G Diagram
|
EXPRESS Definition |
EXPRESS-G Diagram |
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
D IfcDimensionCount
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A IfcAxis2Placement B IfcBooleanOperand C IfcCsgSelect T IfcTrimmingSelect V IfcVectorOrDirection
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B IfcBooleanOperator P IfcProfileTypeEnum T IfcTransitionCode
IfcTrimmingPreference
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
This part of the Industry Foundation Classes specifies the resources for the geometric and topological representation of the shape of a product. The specifications within the IfcGeometryResource include:
- explicit geometric and topological representation
of the shape- attribute driven representation
of standard shapes and shape characteristics.
The explicit geometric and topological representation of the shape is defined following an adaptation of the ISO/CD 10303-42:1992, Industrial Automation Systems and Integration: Product Data Representation and Exchange – Part 42: Integrated Generic Resources. Geometric and Topological Representation. The type, class, and function semantic definition sections follow the adapted wording of the working draft, which is clearly indicated and quoted at each reference. The definitions on explicit geometric and topological representation are explicitly excluded from the copyright of the International Alliance of Interoperability
For more information on the definitions as defined in the formal ISO standard please refer to: ISO/IS 10303-42:1994, Industrial Automation Systems and Integration: Product Data Representation and Exchange – Part 42: Integrated Generic Resources. Geometric and Topological Representation. The formal standard can be obtained through the local publishers of standards in each individual country.
The following is within the scope of the explicit geometric and topological representation in IFC Release 2.0:
In Geometry:
- definition of points directly by their coordinate values
- definition of directions, vectors, and axis placements
- definition of parametric curves (subset of)
- definition of conic curves and elementary surfaces (subset of)
- definition of curves defined on a parametric surface (subset of)
In Topology:
- definition of fundamental topological entities, needed to define faceted B-rep's
In Geometric Shape Models:
- definition of faceted B-rep's
- definition of the creation of solid models by sweeping operations
- definition of half-spaces (subset of)
- definition of constructive solid geometry (CSG) models (subset of)
The attribute driven representation of standard shapes and shape characteristics is defined as the IFC enhancement of the geometry resource. It provides the definition of standard shapes, like extruded area segments or revolved area segments, and characteristics, in particular for the profile and path used within sweep operations to create solid models. The attributes of standard shape characteristics will later be linked to the semantic property definition of the product, so that the product's shape properties will drive the creation of the appropriate shape representation.
The following is within the scope of the attribute driven representation in IFC Release 2.0:
In Attribute Driven Geometric Shape Models:
- definition of two-dimensional bounded areas as profiles
- definition of the creation of solid models by sweeping operations, including multi segments, paths, profiles, tapering, morphing (limited) and cut-out's
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: A dimension count is a positive integer used to define the coordinate space dimensionality.
NOTE Corresponding STEP type: dimension_count, please refer to ISO/IS 10303-42:1994, p. 14 for the final definition of the formal standard.
This Defined Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5
INTEGER
WR1
The dimension count should be an integer between 1 and 3 NOTE: This is a further constraint by IFC, the upper limit does not exist in STEP
{ 0 < SELF <= 3 }
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This select type collects together both versions of the placement as used in two dimensional or in three dimensional Cartesian space. This enables entities requiring this information to reference them without specifying the space dimensionality.
NOTE Corresponding STEP type: axis2_placement, please refer to ISO/IS 10303-42:1994, p. 19 for the final definition of the formal standard.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This select type identifies all those types of entities which may participate in a Boolean operation to form a CSG solid.
Definition from IAI: CSG primitives are out of scope for the current IFC Release 1.5.1 & 2.0.
NOTE Corresponding STEP type: boolean_operand, please refer to ISO/IS 10303-42:1994, p.167 for the final definition of the formal standard. In IFC Release 1.5.1 & 2.0 only Boolean results (IfcBooleanResult), half space solids (IfcHalfSpaceSolid), faceted B-Rep, extruded solids and revolved solids (IfcSolidModel) are defined for being valid Boolean operands.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5.1
ISSUE: See I-330 for changes made in IFC Release 1.5.1
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This type identifies the types of entity which may be selected as the root of a CSG tree including a single CSG primitive as a special case (currently not in IFC).
Definition from IAI: In the current IFC Release 2.0 only Boolean result (IfcBooleanResult) is defined for being a root tree expression (at IfcCsgSolid). CSG primitives are out of scope for the current IFC Release 2.0.
NOTE Corresponding STEP type: csg_select, please refer to ISO/IS 10303-42:1994, p.168 for the final definition of the formal standard.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5.1
ISSUE: See I-330 for changes made in IFC Release 1.5.1
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This select type identifies the two possible ways of trimming a parametric curve; by a Cartesian point on the curve, or by a REAL number defining a parameter value within the parametric range of the curve.
NOTE Corresponding STEP type: trimming_select, please refer to ISO/IS 10303-42:1994, p. 20 for the final definition of the formal standard.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.0
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This type is used to identify the types of entity which can participate in vector computations.
NOTE Corresponding STEP type: vector_or_direction, please refer to ISO/IS 10303-42:1994, p. 20 for the final definition of the formal standard.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This type defines the three Boolean operators used in the definition of CSG solids.
NOTE Corresponding STEP type: boolean_operator, please refer to ISO/IS 10303-42:1994, p.167 for the final definition of the formal standard.
This Enumeration has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.5.1
ISSUE: See I-330 for changes made in IFC Release 1.5.1
Union
The operation of constructing the regularized set theoretic union of the volumes defined by two solids.
Intersection
The set theoretic difference between volumes defined by two solids.
Difference
The operation of constructing the regularized set theoretic intersection of the volumes defined by two solids.
EXPRESS Definition
Definition from IAI: The enumeration defines whether the attribute driven definition of a profile shape shall be geometrically resolved into a curve or into a surface.
This Enumeration has changed after IFC Release 1.5.1, please see the Migration Guide for details
New type in IFC Release 1.5.
Curve
The resulting geometric item is of type IfcBoundedCurve and being closed. The resulting swept solid will then define only the bounding surfaces. This can be used to define shapes with thin sheets, such as ducts, where the thickness is not appropriate for geometric representation.
Area
The resulting geometric item is of type IfcCurveBoundedPlane. The resulting swept solid will be a three-dimensional body with defined volume.
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This type conveys the continuity properties of a composite curve or surface. The continuity referred to is geometric, not parametric continuity. For example, in ContSameGradient the tangent vectors of successive segments will have the same direction, but may have different magnitude.
NOTE Corresponding STEP type: transition_code, please refer to ISO/IS 10303-42:1994, p. 14 for the final definition of the formal standard.
This Enumeration has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.0
Discontinuous
The segments do not join. This is permitted only at the boundary of the curve or surface to indicate that it is not closed.
Continuous
The segments join but no condition on their tangents is implied.
ContSameGradient
The segments join and their tangent vectors or tangent planes are parallel and have the same direction at the joint: equality of derivatives is not required.
ContSameGradientSameCurvature
For a curve, the segments join, their tangent vectors are parallel and in the same direction and their curvatures are equal at the joint: equality of derivatives is not required. For a surface this implies that the principle curvatures are the same and the principle directions are coincident along the common boundary.
EXPRESS Definition
Definition from ISO/CD 10303-42:1992: This type is used to describe the preferred way of trimming a parametric curve where the trimming is multiply defined.
NOTE Corresponding STEP type: trimming_preference, please refer to ISO/IS 10303-42:1994, p. 18 for the final definition of the formal standard.
This Enumeration has changed after IFC Release 1.5.1, please see the Migration Guide for details
New Type in IFC Release 1.0
Cartesian
Indicates that trimming by Cartesian point is preferred.
Parameter
Indicates the preference for the parameter value.
Unspecified
Indicates that no preference is communicated.
 Fully Attributed View |
EXPRESS Definition |
Definition from IAI: An Ifc2DCompositeCurve is an IfcCompositeCurve that is defined within the coordinate space of an IfcPlane. Therefore the dimensionality of the Ifc2DCompositeCurve has to be 2.
NOTE This class has been introduced to get a more straight forward definition of surface boundaries that its counterpart in STEP: composite_curve_on_surface and boundary_curve. Since the only basis elementary surface in IFC1.5 is the plane surface, a two dimensional composite curve provides enough capability to define the boundary.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
IfcGeometricRepresentationItem
IfcCurve
No attributes defined on this level.
WR51
The composite curve shall be closed.
SELF\IfcCompositeCurve.ClosedCurve
WR52
The dimensionality of the composite curve shall be 2
SELF\IfcBoundedCurve.Dim = 2
IP31
A bounded curve has finite arc length.
IP32
A bounded curve has a start point and an end point.
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcArbitraryProfileDef defines an arbitrary two-dimensional boundary to represent a profile for the use within the attribute driven geometry. It is given by an IfcBoundedCurve, from which the surface for extrusion or the surface of revolution can be constructed.
ILLUSTRATION:
Position
The Position attribute of the supertype for this class IfcAttDrivenProfileDef defines the 2D Placement of the Profile within the X'’Y'’ coordinate system, in which the bounded curve is defined. It is overwritten to Location [0.,0.] and RefDirection [1.,0.] as the ProfileDef shall not be subjected to an additional placement. Therefore the ProfileDef coordinate system (X’’Y’’) shall be identical with the XY plane of the coordinate system defined by the IfcAttDrivenExtrudedSegment or the IfcAttDrivenRevolvedSegment.
The IfcArbitraryProfileDef is later positioned within the X'Y' Plane of the coordinate system defined by the
- IfcAttDrivenExtrudedSegment.Position, or by the
- IfcAttDrivenRevolvedSegment.Position.
The Position attribute defines a three dimensional placement coordinate system relative to the coordinate system, given by the IfcLocalPlacement of the semantic object for which it is the attribute driven geometric representation.
Within the X'Y' Plane as defined by the IfcAttDrivenExtrudedSegment or the IfcAttDrivenRevolvedSegment, the inherited two dimensional Position attribute defines a two-dimensional placement coordinate system (X’’Y’’) for the IfcBoundedCurve. The space dimensionality of the IfcBoundedCurve is therefore restricted to be 2. The location and the x-and y-axis directions are the same.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5.
ISSUE: See issues I-239, I-291 for changes made in IFC Release 1.5.
IfcAttDrivenProfileDef
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
CurveForSurface
The definition of the closed boundary for the profile definition in terms of explicit geometry.
DER
Position
SELF
Overwritten placement definition from the supertype IfcAttDrivenProfileDef. Always defines location [0.,0.] and RefDirection [1.,0.]
WR21
The IfcBoundedCurve used for curve for surface definition shall have the dimensionality of 2.
CurveForSurface.Dim = 2
IP21
The IfcBoundedCurve used for curve for surface definition shall always be a closed bounded curve.
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenClippedExtrudedSolid defines a multi-segment extrusion solid by means of attribute driven geometric representation items. It is defined by
- list of extruded segments, each defining the placement coordinate system, the extrusion depth and the area of extrusion for this segment (inherited from supertype IfcAttDrivenExtrudedSolid), and
- list of half spaces, used to clip the extruded solids, that have been concatenated by a Boolean Union operation before. The half spaces are subtracted from the extruded solid in the order of their appearance in the list.
The half spaces are defined in the object coordinate system, as defined by the local placement of the semantic object.
ILLUSTRATION:
Each IfcAttDrivenClippedExtrudedSolid additionally defines a list of half spaces, used to clip the multi-segment extruded solid. The Boolean operation "Difference" is applied between the union of Segments and each of the Clipping Half Spaces.
The result is an solid, defined by the union of all Segments and difference with each half space.
Object Geometry in Context:
Example:
The figure shows the usage of IfcAttDrivenClippedExtrudedSolid to define a stepped trapezoidal solid with a sloping.
- Black arrows show LCS of IfcLocalPlacement (Object Coordinate System)
- Blue arrows show LCS of first IfcAttDrivenExtrudedSegment (defined by Position attribute)
- Green arrows show LCS of second IfcAttDrivenExtrudedSegment (defined by Position attribute)
The clipping Half Space (here unbounded) is defined in the LCS of IfcLocalPlacement (black arrows)
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issue I-288 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
ClippingHalfSpaces
LIST [1:?] OF IfcHalfSpaceSolid
Half spaces defined in Object Coordinate System of IfcLocalPlacement, that are used to clip the extruded solid.
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenClippedRevolvedSolid defines a revolved solid by means of attribute driven geometric representation items. It is defined by
- list of revolved segments, each defining the start and sweep angle of revolution and the area of revolution for this segment, and
- list of half spaces, used to clip the extruded solids, that have been concatenated by a Boolean Union operation before. The half spaces are subtracted from the extruded solid in the order of their appearance in the list.
The half spaces are defined in the coordinate system, defined by the local placement of the semantic object.
ILLUSTRATION:
Each IfcAttDrivenClippedRevolvedSolid additionally defines a list of half spaces, used to clip the multi-segment extruded solid. The Boolean operation "Difference" is applied between the union of Segments and each of the Clipping Half Spaces.
The result is an solid, defined by the union of all Segments and difference with each half space.
Object Geometry in Context
Example:
The figure shows the usage of IfcAttDrivenClippedRevolvedSolid to define a stepped trapezoidal rotated solid with a sloping base.
- Black arrows show LCS of IfcLocalPlacement (Object Coordinate System)
- Blue arrows show LCS of first IfcAttDrivenRevolvedSegment (defined by Position attribute)
- Green arrows show LCS of second IfcAttDrivenRevolvedSegment (defined by Position attribute)
Both, first and second segment, refer to the same physical instance of LCS, IfcAxis2Placement3D. The clipping Half Space (here unbounded) is defined in the LCS of IfcLocalPlacement (black arrows)
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issue I-288 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
ClippingHalfSpaces
LIST [1:?] OF IfcHalfSpaceSolid
Half spaces defined in Object Coordinate System of IfcLocalPlacement, that are used to clip the extruded solid.
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenExtrudedSegment is the attribute driven definition of an extruded area solid segment of the multi-segment swept solid, the IfcAttDrivenExtrudedSolid. It is defined by a swept area, provided by the start profile definition, which remains unchanged over the extruded depth. This swept area is extruded along the extrusion direction, as given by the IfcAttDrivenExtrudedSolid.
The following parameter are specified:
- placement within a three dimensional coordinate system,
- profile definition, defines the extruded area by attributes according to standard forms, or by an arbitrary closed bounded curve,
- extruded area (inherited from supertype IfcSweptAreaSolid), derived by function IfcProfileIntoArea out of the profile definition,
- extruded direction (inherited from supertype IfcExtrudedAreaSolid), derived as being along the z- axis, defined by the position of the IfcAttDrivenExtrudedSolid,
- extruded depth (inherited from supertype IfcExtrudedAreaSolid)
ILLUSTRATION:
The IfcAttDrivenExtrudedSegment defines its own three-dimensional placement coordinate system relative to the coordinate system provided by the IfcLocalPlacement of the semantic object for which it is the attribute driven geometric representation.
The IfcAttDrivenExtrudedSegment is defined by a start profile definition. From this profile definition the swept area is derived.
The extrusion is always in the direction of the normal of the swept area.
The swept area is provided as IfcCurveBoundedPlane with the basis surface of IfcPlane. The position of the IfcPlane, also defining the normal of the plane, is identical to the placement coordinate system, as defined by the IfcAttDrivenExtrudedSolid.
Each segment is located by its own placement coordinate system relative to the coordinate system provided by the IfcLocalPlacement.
A constraint applies to all placement coordinate systems of segments within one IfcAttDrivenExtrudedSolid. The Z' Axis of placement coordinate system of all segments shall be defined along a line.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New entity in IFC Release 1.5.
ISSUE: See issues I-028, I-234, I-292 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
IfcAttDrivenTaperedExtrudedSegment
IfcAttDrivenMorphedExtrudedSegment
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
Position
Placement of the extruded solid segment relative to the local coordinate system of the product.
ProfileDef
The attribute driven definition of the profile, from which the swept area can be derived.
DER
SweptArea
SELF
The derived swept area, that specifies the surface defining the area to be swept. It is defined as a bounded planar surface, coplanar with the X'Y' plane of the placement coordinate system.
DER
ExtrudedDirection
SELF
The derived direction, in which the surface is to be swept. It is always in the direction of the z-axis of the placement coordinate system, as defined by the IfcAttDrivenExtrudedSolid, and thereby identical with the normal of the swept area.
INV
PartOfSolid
The reference to the IfcAttDrivenExtrudedSolid, for which it defines a segment.
WR51
Only Profile Definitions, defining an area for extrusion are valid for ProfileDef.
ProfileDef.ProfileType = Area
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenExtrudedSolid defines a multi-segment extrusion solid by means of attribute driven geometric representation items. It is defined by
- list of extruded segments, each defining the placement coordinate system, the extrusion depth and the area of extrusion for this segment.
The resulting solid is the union of all segments. The IfcAttDrivenExtrudedSolid also provides the derived definition of the extrusion path. The applied convention hereby is, that the extruded direction is always along the Z- Axis of the placement coordinate systems, defined by the Position attribute within all Segments. The extrusion depth parameter are defined for each Segment, therefore the path length is the sum of all extrusion depths as specified by the extruded segments.
Example:
The implied extrusion path is defined along the Z' axes of the placement coordinate systems of all Segments. For each extruded segment there is an extrusion depth definition provided. Those extrusion depths are defined consecutively. The complete extrusion path has the length of the sum of all extrusion depths defines in the Segment list.
The IfcAttDrivenExtrudedSolid therefore allows for multiple segment solids. Since only multiple straight segments along the same line are allowed, there are no conflicts at the joints.
Each IfcAttDrivenExtrudedSegment within the list of Segments defines an solid of linear extrusion. The IfcAttDrivenExtrudedSolid provides the formal and informal propositions to ensure, that a common extrusion direction is specified for all Segments.
The result is an solid, defined by the union of all Segments.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issue I-027, I-228, I-229, I-230, I-292 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
Segments
LIST [1:?] OF IfcAttDrivenExtrudedSegment
Definition of extruded segments, each segment has a start and can have a different end swept area, provided by an attribute driven profile definition. If the start profile is not identical with the end profile of the previous segment, that a stepped extrusion solid is generated.
DER
Path
The derived specification of the extrusion path, given by a polyline as explicit geometric representation.
WR31
The P[3] attribute (Z axis) of all Segments shall have the same direction.
SIZEOF(QUERY( Temp <* Segments | Temp.Position.P[3] <> Segments[1].Position.P[3])) = 0
IP31
The Location attribute of the Position for all Segments shall guarantee, that the Z-axis of all placement coordinate systems of all Segments shall be defined along a line.
IP32
The Location attribute of the Position for all Segments shall guarantee, that the start surface of the next Segment is coplanar with the end surface of the previous Segment.
Object Geometry in Context
Example:
The figure shows the usage of IfcAttDrivenExtrudedSolid to define a stepped trapezoidal solid.
- Black arrows show LCS of IfcLocalPlacement (Object Coordinate System)
- Blue arrows show LCS of first IfcAttDrivenExtrudedSegment (defined by Position attribute)
- Green arrows show LCS of second IfcAttDrivenExtrudedSegment (defined by Position attribute)
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenMorphedExtrudedSegment is the attribute driven definition of an extruded area solid segment of the multi-segment swept solid, the IfcAttDrivenExtrudedSolid. It is defined by a starting swept area, provided by the start profile definition and the ending swept area, provided by the end profile definition. The morphed extruded segment is restricted in the current release. A set of constrains apply to the definitions of start and end profile. In particular, they shall have the same number of points and the same type of segments between each two consecutive points.
The geometric resolution of the resulting surfaces and/or volume is left for the receiving application. The constraints applied in formal and informal propositions, however, limit results.
ILLUSTRATION:
The IfcAttDrivenMorphedExtrudedSegment provides an end profile definition from with the ending swept area is derived.
The start profile, extruded direction and depth are specified at the supertype IfcAttDrivenExtrudedSegment. The same conventions apply.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New entity in IFC Release 1.5
ISSUE: See issues I-031, I-237, I-293 for changes made in IFC Release 1.5
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
EndProfileDef
The attribute driven definition of the profile, from which the swept area can be derived.
DER
EndSweptArea
The derived swept area, that specifies the surface defining the area to be swept.
WR61
The type of start profile definition shall be the same as the type of end profile definition.
TYPEOF(SELF\IfcAttDrivenExtrudedSegment.ProfileDef) = TYPEOF(EndProfileDef)
WR62
The use of IfcArbitraryProfileDef is not allowed for morphing profiles.
NOT('IFCGEOMETRYRESOURCE.IFCARBITRARYPROFILEDEF' IN TYPEOF(SELF\IfcAttDrivenExtrudedSegment.ProfileDef))
WR63
The relative position of start and end profiles shall have the same orientation.
SELF\IfcAttDrivenExtrudedSegment.ProfileDef.Position.P[1] = EndProfileDef.Position.P[1]
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenMorphedRevolvedSegment is the attribute driven definition of an revolved area solid segment of the multi-segment swept solid, the IfcAttDrivenRevolvedSolid. It is defined by a starting swept area, provided by the start profile definition and the ending swept area, provided by the end profile definition. The morphed revolved segment is restricted in the current release. A set of constrains apply to the definitions of start and end profile. In particular, they shall have the same number of points and the same type of segments between each points. This swept area is extruded around the axis.
The geometric resolution of the resulting surfaces and/or volume is left for the receiving application. The constraints applied in formal and informal propositions, however, limit results.
ILLUSTRATION:
The IfcAttDrivenMorphedRevolvedSegment provides an end profile definition from with the ending swept area is derived.
The start profile, axis and angle are specified at the supertype IfcAttDrivenRevolvedSegment. The same conventions apply.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New entity in IFC Release 1.5
ISSUE: See issue I-031, I-238 for changes made in IFC Release 1.5
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
EndProfileDef
The attribute driven definition of the profile, from which the swept area can be derived.
DER
EndSweptArea
The derived swept area, that specifies the surface defining the area to be swept.
WR61
The type of start profile definition shall be the same as the type of end profile definition.
TYPEOF(SELF\IfcAttDrivenRevolvedSegment.ProfileDef) = TYPEOF(EndProfileDef)
WR62
The use of IfcArbitraryProfileDef is not allowed for morphing profiles.
NOT('IFCGEOMETRYRESOURCE.IFCARBITRARYPROFILEDEF' IN TYPEOF(SELF\IfcAttDrivenRevolvedSegment.ProfileDef))
WR63
The relative position of start and end profiles shall have the same orientation.
SELF\IfcAttDrivenRevolvedSegment.ProfileDef.Position.P[1] = EndProfileDef.Position.P[1]
IP51
The sum of Start Angle and Angle (as defined in supertype IfcRevolvedAreaSolid) shall be between 0° and 360°, or 0 and 2p (depending on the unit type for Plane Angle Measure).
|
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenProfileDef is the supertype of all attribute driven definitions of the profile (or cross section) geometry in IFC. It is used to define a standard set of commonly used shapes of profiles including their attributes.
Currently all IfcAttDrivenProfileDef are treated as bounded areas, as they are used within the IfcAttDrivenExtrudedSegment or IfcAttDrivenRevolvedSegment for swept area solids. In other words, the inside of an IfcAttDrivenProfileDef is a part of the profile. The inside is defined in a way consistent with that for ISO 10303-42:1994 curve_bounded_surface.
ILLUSTRATION:
The IfcAttDrivenProfileDef defines a two-dimensional placement coordinate system for the attribute driven profile definitions of standard forms, relative to the coordinate system in which the resulting bounded curve is defined.
In the later use of the IfcAttDrivenProfileDef within the
- IfcAttDrivenExtrudedSolid or the
- IfcAttDrivenRevolvedSolid
the underlying coordinate system of the resulting bounded curve (X’’Y’’) is placed at the Location of the Position defined by the IfcAttDrivenExtrudedSegment or IfcAttDrivenRevolvedSegment (X’Y’) and the x- and y- axis directions are the same.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issues I-033, I-183, I-239 for changes made in IFC Release 1.5.
IfcAttDrivenProfileDef
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
Position
Placement of the profile within the X'Y' plane defined by the Path Definition.
ProfileType
Defines the type of geometry into which this profile definition shall be resolved, either bounded curve or bounded surface
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenRevolvedSegment is the attribute driven definition of an revolved area solid segment of the multi-segment swept solid, the IfcAttDrivenRevolvedSolid. It is defined by a swept area, provided by the definition of the start profile, which is rotated over the revolved angle.
The following parameter are specified:
- placement within a three dimensional coordinate system, that defines the position of the normal of the first segment,
- profile definition, which defines the revolved,
- revolved area (inherited from supertype IfcSweptAreaSolid), derived by function IfcProfileIntoArea out of the profile definition,
- axis for revolution (inherited from supertype IfcRevolvedAreaSolid),
- sweep angle (inherited from supertype IfcRevolvedAreaSolid)
- start angle
ILLUSTRATION:
The IfcAttDrivenRevolvedSegment defines its own three-dimensional coordinate system relative to the coordinate provided by the IfcLocalPlacement of the semantic object for which it is the attribute driven geometric representation.
The IfcAttDrivenRevolvedSegment is defined by a start profile definition. From this profile definition the swept area is derived.
The revolution is always around the axis, which has to be identical for all Segments.
The swept area is provided as IfcCurveBoundedPlane with the basis surface of IfcPlane. The position of the IfcPlane, also defining the normal of the plane, is identical to the placement coordinate system, as defined by the IfcAttDrivenRevolvedSolid.
If the said IfcAttDrivenRevolvedSegment is not the first of the list of Segments at the IfcAttDrivenRevolvedSolid, i.e. the StartAngle <> 0.0, then the SweptArea is first rotated by the value of StartAngle.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New entity in IFC Release 1.5.
ISSUE: See issues I-028, I-235, I-292 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
Position
Placement of the revolved solid relative to the local coordinate system of the product.
StartAngle
Angle by which the SweptArea is rotated first, before the revolution by the Angle.
ProfileDef
The attribute driven definition of the profile, from which the swept area can be derived.
DER
SweptArea
SELF
The derived swept area, that specifies the surface defining the area to be swept.
INV
PartOfSolid
The reference to the IfcAttDrivenExtrudedSolid, for which it defines a segment.
WR51
The Location of the sweep Axis shall always be defined at the X'Y' plane of the placement coordinate system.
SELF\IfcRevolvedAreaSolid.Axis.Location.Coordinates[3] = 0
WR52
ProfileDef.ProfileType = Area
IP51
The sum of Start Angle and Angle (as defined in supertype IfcRevolvedAreaSolid) shall be between 0° and 360°, or 0 and 2p (depending on the unit type for Plane Angle Measure).
|
Fully Attributed View |
EXPRESS Definition |
Definition from IAI: The IfcAttDrivenRevolvedSolid defines a revolved solid by means of attribute driven geometric representation items. It is defined by
- list of revolved segments, each defining the start and sweep angle of revolution and the area of revolution for this segment.
The resulting solid is the union of all segments. The IfcAttDrivenRevolvedSolid also provides the derived definition of the arc defining the path of revolution. The arc starts in the origin, given by the location of the placement coordinate system of the first Segment. The angle of revolution parameters are defined at each Segment, where the start angle equals to the start angle + sweep angle of the previous Segment. The arc length of the path is therefore derived from the start angle + sweep angle at the last Segment.
The IfcAttDrivenRevolvedSolid also provides constraints for the placement coordinate systems of the Segments, all shall refer to the same instance of IfcAxis2Placement3D. In addition, the Axis defined at all Segments shall be identical.
ILLUSTRATION:
For each revolved Segment there is an start and sweep angle definition provided. The complete revolution arc has the arc length of the sum of all sweep angles defines in the Segment list.
The IfcAttDrivenRevolvedSolid therefore allows for multiple segment solids. Since all segments have the same axis, there are no conflicts at the joints.
Each IfcAttDrivenRevolvedSegment within the list of Segments defines an solid of revolution. The IfcAttDrivenRevolvedSolid ensures the use of a common placement coordinate system an a common axis for all Segments. The result is the union of all Segments.
Object Geometry in Context:
Example:
The figure shows the usage of IfcAttDrivenRevolvedSolid to define a stepped trapezoidal rotated solid.
- Black arrows show LCS of IfcLocalPlacement (Object Coordinate System)
- Blue arrows show LCS of first IfcAttDrivenRevolvedSegment (defined by Position attribute)
- Green arrows show LCS of second IfcAttDrivenRevolvedSegment (defined by Position attribute)
Both, first and second segment, refer to the same physical instance of LCS, IfcAxis2Placement3D.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issues I-027, I-231, I-232, I-233, I-292, I-294 for changes made in IFC Release 1.5.
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
Segments
LIST [1:?] OF IfcAttDrivenRevolvedSegment
Definition of revolved segments, each segment has a start and can have a different end swept area, provided by an attribute driven profile definition. If the start profile is not identical with the end profile of the previous segment, that a stepped solid is generated.
DER
Path
The derived specification of the path of revolution, given by a trimmed curve as explicit geometric representation.
WR31
All Segments shall reference the same instance of the placement coordinate system.
SIZEOF(QUERY( Temp <* Segments | Temp.Position :<>: Segments[1].Position)) = 0
WR32
All Segments shall define an identical Axis for revolution.
SIZEOF(QUERY( Temp <* Segments | Temp\IfcRevolvedAreaSolid.Axis <> Segments[1]\IfcRevolvedAreaSolid.Axis)) = 0
IP41
The Axis Line shall lie in the plane of the Swept Area (as defined at supertype IfcSweptAreaSolid).
IP42
The Axis Line shall not intersect the interior of the Swept Area (as defined at supertype IfcSweptAreaSolid).
IP43
The Angle shall be between 0° and 360°, or 0 and 2p (depending on the unit type for Plane Angle Measure).
|
Fully Attributed View |
EXPRESS Definition |
The IfcAttDrivenTaperedExtrudedSegment is the attribute driven definition of an extruded area solid segment of the multi-segment swept solid, the IfcAttDrivenExtrudedSolid. It is defined by a start swept area, provided by the start profile definition, which will be linearly changed during the sweep operation according to a tapering ratio. Therefore the implicitly defined end swept area is a scaled variant of the start swept area.
ILLUSTRATION:
The start profile, extruded direction and depth are specified at the supertype IfcAttDrivenExtrudedSegment. The same conventions apply.
The end profile is implicitly calculated by applying the tapering ratio to the start profile. The tapering factor describes whether the profile increases (factor > 1.0) or decreases (1.0 > factor > 0.0). The position of the profile against the path is important, since the tapering factor takes this relative position into account.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5.
ISSUE: See issue I-296 for changes made in IFC Release 1.5
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
TaperingFactor
The ratio that defines the increase/decrease of the profile along the extrusion vector.
|
Fully Attributed View |
EXPRESS Definition |
The IfcAttDrivenTaperedRevolvedSegment is the attribute driven definition of an revolved area solid segment of the multi-segment swept solid, the IfcAttDrivenExtrudedSolid. It is defined by a start swept area, provided by the start profile definition, which will be linearly changed during the sweep operation according to a tapering ratio factor. Therefore the implicitly defined end swept area is a scaled variant of the start swept area.
ILLUSTRATION:
The start profile, axis and angle are specified at the supertype IfcAttDrivenRevolvedSegment. The same conventions apply.
The end profile is implicitly calculated by applying the tapering ratio to the start profile. The tapering factor describes whether the profile increases (factor > 1.0) or decreases (1.0 > factor > 0.0). The position of the profile against the path is important, since the tapering factor takes this relative position into account.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5.
ISSUE: See issue I-296 for changes made in IFC Release 1.5
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
TaperingFactor
The ratio that defines the increase/decrease of the profile along the extrusion vector.
|
Fully Attributed View |
EXPRESS Definition |
Definition from ISO/CD 10303-42:1992: The direction and location in three dimensional space of a single axis. An IfcAxis1Placement is defined in terms of a locating point (inherited from IfcPlacement supertype) and an axis direction: this is either the direction of Axis or defaults to (0.0,0.0,1.0). The actual direction for the axis placement is given by the derived attribute Z.
NOTE Corresponding STEP name: axis1_placement, please refer to ISO/IS 10303-42:1994, p. 28 for the final definition of the formal standard.
Illustration:
Definition of the IfcAxis1Placement within the three-dimensional coordinate system.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
New class in IFC Release 1.5
ISSUE: See issue I-008 for changes made in IFC Release 1.5.
See issues I-332, I-344 for changes made in IFC Release 1.5.1
IfcGeometricRepresentationItem
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
OPT
Axis
The direction of the local Z axis
DER
