EXPRESS Definition
EXPRESS-G Diagram
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EXPRESS Definition |
EXPRESS-G Diagram |
No Simple Types defined in this Schema
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
R IfcReferenceCurveSelect
IfcReferencePointSelect
No Enumerations defined in this Schema
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
No Functions defined in this Schema
Core extensions, as the name implies, provide extensions to concepts rooted in the kernel. Thus, Core extensions are the first refinement layer for abstract kernel constructs. Each core extension is a specialization of classes defined in the Kernel.
The IfcModelingAidExtension schema defines basic object concepts used as aids in the development of project models, particularly those related to geometric placement, alignment or constraint. Therefore, these "aids", or helper objects, do not include primary elements defining the model, but provide references for the definition of such primary elements (which are generally defined in other Core Extension schemata).
EXPRESS Definition
Definition from IAI: IfcReferenceCurveSelect is a select type which enables selection of reference geometry curve alternatives. Such curves can be used as modeling aids in the placement and alignment of other objects.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
EXPRESS Definition
Definition from IAI: IfcReferencePointSelect is a select type which enables selection of reference geometry point alternatives. Such points can be used as modeling aids in the placement and alignment of other objects.
This Select Type has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
 Fully Attributed View |
EXPRESS Definition |
Definition from IAI: Provides a specialization of IfcLocalPlacement in which placement is limited (controlled) by one or more constraints. In this release, there is a single type of constraint introduced: IfcConstraintRelIntersection.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-139, IfcPlacementConstraint and IfcConstraintRelIntersection for related discussion.
IfcRoot
IfcModelingAid
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
PathEndPointsConstraint
LIST [1:2] OF IfcPlacementConstraint
A constraint on one or both ends of the path for an ExtrudedSolid
This class has no geometry.
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EXPRESS Definition |
Definition from IAI: Objects of this type provide a constraint that can be used to control the local placement of Products, Modeling Aids and Proxy objects. Specifically, objects of this type constrain an end point of the path for an IfcAttDrivenExtrudedSolid by defining offsets from a Reference point on a reference Path. Generally this will be used to locate an endpoint for such paths relative to intersections in a Design Grid.
This is the only placement constraint introduced in this IFC Release. However, other constraints, relative to Reference Curves and Reference Surfaces are planned in future releases.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-139, IfcConstrainedPlacement and IfcPlacementConstraint for related discussion.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
RefPointAt
Intersection, relative to which the Path endpoint will be located
OffsetFromCurves
LIST [0:3] OF IfcReferenceCurveSelect
Reference curves from which fixed offsets are defined in OffsetDistances
OffsetDistances
LIST [0:3] OF IfcLengthMeasure
Fixed offset distances from reference lines. Note that if one offset is provided, there are two degrees of free movement; if two offsets are defined, there is still one degree of free movement; if all three offsets (and curves are defined, the placement is fully constrained
This class has no geometry.
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EXPRESS Definition |
Definition from IAI: A 3D grid used as an aid in locating structural and design elements. An IfcDesignGrid contain a list of IfcGridLevels – which contain IfcGridAxes and IfcGridIntersections. All of these objects define a grid system, relative to which project objects will be placed.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
OPT
GridPurpose
STRING
Descriptive purpose of the grid. NOTE: this grid can be orthogonal, angular, polar, and include different 2D grids on each level. It can be used for a structural grid, planning grid, or any type of grid to which objects will be aligned.
LocalPlacement
Origin and orientation for this grid - relative to another object. Establishes the Local Coordinate System relative to the Coordinate System referenced in "PlacementRelativeTo"
INV
HasGridLevels
SET [1:?] OF IfcGridLevel
Set of inverse relationships to Grid Levels. Inverse for PartOfDesignGrid
The IfcDesignGrid does not include geometry directly, other than the coordinating reference geometry placement used by all grid elements contained (e.g. the contained IfcGridLevels (Axes and Intersections)).
Object Geometry in Context
Contained grid elements geometry example
Reference Geometry
The IfcAxis2Placement is used to define the common local object coordinate system for multiple shape representations for this class: The reference placement is defined by:
Parameters IfcDesignGrid.LocalPlacement
Type IfcLocalPlacement
Standard 3D Geometric Representation
All geometry for this object is defined in the contained objects (grid level and grid axes), all of which are placed relative to the reference geometry defined above.
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Fully Attributed View |
EXPRESS Definition |
Definition from IAI: An individual Axis in a Design Grid. In this release, Axes use an IfcBoundedCurve for geometry.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
PartOfGridLevel
Elevation for this grid axis, relative to the origin for this grid
OPT
AxisTag
STRING
The tag or name for this grid axis
AxisCurve
BoundedCurve which provides the geometry for this Grid Axis
SameSenseAsBaseCurve
BOOLEAN
Defines whether the original sense of curve is used or whether it is reversed in the context of the grid
INV
AlignedGridIntersections
SET [0:?] OF IfcGridIntersection
Inverse relationship to Intersections aligned with this Axis. Inverse for AlignedWithAxes.
Object Geometry in Context
IfcGridAxis – shown in context of complete IfcDesignGrid
Reference Geometry
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid.
Standard 3D Geometric Representation
IfcGridAxis uses an IfcBoundedCurve entity for its geometry.
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EXPRESS Definition |
Definition from IAI: An Individual intersection of two or more Grid Axes at a 3D point in space. This point is represented by a Cartesian Point.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
AlignedWithAxes
SET [2:?] OF IfcGridAxis
Set of relationships to 2 or more grid axes for which this point is an intersection
IntersectionPoint
3D geometric point at the intersection of 2 or more Grid Axes.
Object Geometry in Context
IfcGridIntersection shown in the context of an IfcDesignGrid.
Reference Geometry
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid.
Standard 3D Geometric Representation
IfcGridIntersection uses an IfcCartesianPoint entity for its geometry.
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EXPRESS Definition |
Definition from IAI: An XY planar Level in a 3D Design Grid. IfcGridLevel contains a list of IfcGridAxes
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
PartOfDesignGrid
Relationship of this Grid Level to the Design Grid for which it is a part
OPT
GridLevelHeight
Elevation for this grid level, relative to the origin for the IfcDesignGrid to which this level belongs
OPT
GridLevelName
STRING
Description for this level in the grid (e.g. Floor 1, Floor 3-mechanical, Penthouse)
INV
HasGridAxes
SET [1:?] OF IfcGridAxis
Set of relationships to Grid Axes that are part of this grid level. Inverse for PartOfGridLevel
IfcGridLevel does not include geometry directly. However, it does contain a list of IfcGridAxis elements, each of which has geometry.
Object Geometry in Context
IfcGridLevel shown in the context of an IfcDesignGrid.
Reference Geometry
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid.
Standard 3D Geometric Representation
All geometry for this object is defined in the contained objects (grid axes and intersections).
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EXPRESS Definition |
Definition from IAI: An object representing a source of light (e.g. the Sun or an electrical light fixture). Note: geometry for that light source will be defined on the physical object which references this object (e.g. IfcLightFixture).
New Class in IFC Release 2.0
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
SpectralPowerDistribution
LIST [1:?] OF IfcMeasureWithUnit
List of Power/Wavelength value pairs
PhotometricOutputDistribution
LIST [1:?] OF IfcPhotometricOutputSpace
List of Intensity/VolumeMeasure
IfcLightSource does not include geometry directly. Instead, geometry is defined by the physical objects which contain it (e.g. IfcLightFixture).
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EXPRESS Definition |
Definition from IAI: Space around a luminaire to which a specified average light intensity is radiated..
New Class in IFC Release 2.0
ISSUES: None.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
OutputSpace
3D space through which light is cast by the light source. Placement should be relative to the placement of the light source.
OutputIntensity
Light intensity for this space
Geometry for this object is defined by the contained space object.
Object Geometry in Context
3D volume (space) in which luminous output intensity from the associated light source is equal.
Reference Geometry
Reference geometry for this object (placement) is provided by the light source object to which it is related (e.g. IfcLightFixture). This geometry is defined relative to the placement for this light source object.
Standard 3D Geometric Representation
An IfcSolidModel is used to represent the 3D volume.
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EXPRESS Definition |
Definition from IAI: Provides an abstract supertype for multiple types of constraints on placement definitions for Products, Modeling Aids and Proxys.
In this IFC release, there is only a single type of constraint introduced: IfcConstraintRelIntersection. However, this supertype has been provided for upward compatibility. This will enable the introduction of other constraints on placement (relative to curves and surfaces) in future releases.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-139 and IfcConstrainedPlacement for discussion.
IfcRoot
IfcConstraintRelIntersection
No attributes defined on this level.
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EXPRESS Definition |
Definition from IAI: Objects of this type provide a reference IfcObject (a 3D curve) relative to which Products and Proxys can be placed. It will typically be used as a Curve (or line) in space that has some significance to the designer; a symmetry line for example. A curve which can be used to constrain the placement of primary model elements (IfcProducts) through the use of IfcConstrainedPlacement. Two other such reference object classes have been included in this IFC release: IfcReferencePoint and IfcReferenceSurface.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-138, IfcReferencePoint and IfcReferenceSurface for related discussion.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
ReferenceCurve
3D geometric curve which can be used as a modeling Aid in the placement of other objects.
Standard 3D Geometric Representation
An IfcBoundedCurve is used as the geometry representation.
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EXPRESS Definition |
Definition from IAI: Supertype for various types of reference geometry entities with 'LocalPlacement' (provided by this class) that can be used to aid or constrain placement or alignment of other objects.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-138, IfcReferenceCurve and IfcReferenceSurface for related discussion.
IfcRoot
IfcReferenceCurve
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
LocalPlacement
Placement, relative to another object in the project
This abstract class does not include geometry directly, other than the coordinating reference geometry placement inherited by all subtypes.
Reference Geometry
The IfcAxis2Placement is used to define the common local object coordinate system for multiple shape representations for this class: The reference placement is defined by:
Parameters IfcReferenceGeometryAid.LocalPlacement
Type IfcLocalPlacement
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Fully Attributed View |
EXPRESS Definition |
Definition from IAI: Objects of this type provide a reference IfcObject (a 3D point) relative to which Products and Proxys can be placed. It will typically be used as a point in space that has some significance to the designer. A point which can be used to constrain the placement of primary model elements (IfcProduct) through the use of IfcConstrainedPlacement. Two other such reference object classes have been included in this IFC release: IfcReferenceCurve and IfcReferenceSurface.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-138, IfcReferenceCurve and IfcReferenceSurface for related discussion.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
ReferencePoint
3D geometric point
Standard 3D Geometric Representation
An IfcCartesianPoint is used as the geometry representation.
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EXPRESS Definition |
Definition from IAI: Objects of this type provide a reference IfcObject (a 3D curve) relative to which Products and Proxys can be placed. It will typically be used as a surface in space that has some significance to the designer; a planar surface for example. A surface which can be used to constrain the placement of primary model elements (IfcProducts) through the use of IfcConstrainedPlacement. Two other such reference object classes have been included in this IFC release: IfcReferencePoint and IfcReferenceSurface.
This Class has changed after IFC Release 1.5.1, please see the Migration Guide for details
ISSUES: See I-138, IfcReferenceCurve and IfcReferencePoint for related discussion.
IfcRoot
Attribute type (OPT, DER, INV)
Redefinition (SELF)
Attribute / Relation
Data or Rel. type
Definition
ReferenceSurface
3D geometric Surface
Standard 3D Geometric Representation
An IfcSurface is used as the geometry representation.
