Index Page
EXPRESS Definition |
EXPRESS-G Diagram |
IDL Definition |
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. 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 the 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.
Select:
IfcReferenceCurve |
|
IfcGridAxis |
|
NOTE This type is new in IFC Release 1.5
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.
Select:
IfcReferencePoint |
|
IfcGridIntersection |
|
NOTE This type is new in IFC Release 1.5
EXPRESS Definition
Definition from IAI: Provides a specialization of IfcLocalPlacement in which placement is limited (controlled) by one or more constraints. In IFC Release 1.5, there is only a single type of constraint introduced: IfcConstraintRelIntersection.
NOTE: This is a new class in IFC Release 1.5.
ISSUE: See I-139, IfcPlacementConstraint and IfcConstraintRelIntersection for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
PathEndPointsConstraint |
A constraint on one or both ends of the path for an ExtrudedSolid |
LIST[1:2][IfcPlacementConstraint |
see type |
see type |
n/a |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry.
Class IfcConstraintRelIntersection
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 IFC Release 1.5. However, other constraints, relative to Reference Curves and Reference Surfaces are planned in future releases.
NOTE: This is a new class in IFC Release 1.5.
ISSUE: See I-139, IfcConstrainedPlacement and IfcPlacementConstraint for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
RefPointAt |
Intersection, relative to which the Path endpoint will be located |
see type |
see type |
n/a |
|
|
OffsetFromCurves |
Reference curves from which fixed offsets are defined in OffsetDistances |
LIST[0:3] IfcReferenceCurveSelect |
see type |
see type |
empty list |
|
OffsetDistances |
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 |
LIST[0:3] IfcLengthMeasure |
see type |
see type |
empty list |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry.
EXPRESS Definition
Contains a list of IfcGridLevels – which contain IfcGridAxes and IfcGridIntersections – all of which define a grid system to which project elements will be aligned.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
GridPurpose |
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. |
STRING |
see type |
see type |
empty string |
|
LocalPlacement |
Origin and orientation for this grid - relative to another object. Establishes the Local Coordinate System relative to the Coordinate System referenced in "PlacementRelativeTo" |
see type |
see type |
n/a |
|
INV |
HasGridLevels |
Set of inverse relationships to Grid Levels. Inverse for PartOfDesignGrid |
SET [1:?] IfcGridLevel |
see type |
see type |
n/a |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
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 |
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
EXPRESS Definition
Individual Axis of a grid; may be any IfcBoundedCurve.
NOTE: Reference to type for AxisTag in Min/Max columns removed in R1.5.1
Attributes and Relationships
|
Attribute / Relation name |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
PartOfGridLevel |
Elevation for this grid axis, relative to the origin for this grid |
see type |
see type |
n/a |
|
|
AxisTag |
The tag or name for this grid axis |
STRING |
see type |
see type |
empty string |
|
AxisCurve |
BoundedCurve which provides the geometry for this Grid Axis |
see type |
see type |
Line from 0,0,0 to 1,1,0 |
|
|
SameSense |
Defines whether the original sense of curve is used or whether it is reversed in the context of the grid |
BOOLEAN |
see type |
see type |
TRUE |
INV |
AlignedGridIntersections |
Inverse relationship to Intersections aligned with this Axis. Inverse for AlignedWithAxes. |
SET [0:?] IfcGridIntersection |
see type |
see type |
NIL |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
Object Geometry in Context
|
IfcGridAxis – shown in context of complete IfcDesignGrid |
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid. IfcGridAxis uses an IfcCurve entity for its geometry.
EXPRESS Definition
Individual intersection of two or more Grid Axes at one specific Cartesian Point.
Attributes and Relationships
|
Attribute / Relation name |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
AlignedWithAxes |
Set of relationships to 2 or more grid axes for which this point is an intersection |
Set [2:N] IfcGridAxis |
see type |
see type |
n/a |
|
IntersectionPoint |
3D geometric point at the intersection of 2 or more Grid Axes. |
see type |
see type |
0.,0.,0. |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
Object Geometry in Context
|
IfcGridIntersection shown in the context of an IfcDesignGrid. |
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid. IfcGridIntersection uses an IfcCartesianPoint entity for its geometry.
EXPRESS Definition
Level of a 3D grid - an IfcGridLevel contains a set of IfcGridAxes
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
PartOfDesignGrid |
Relationship of this Grid Level to the Design Grid for which it is a part |
see type |
see type |
n/a |
|
|
GridLevelHeight |
Elevation for this grid level, relative to the origin for the IfcDesignGrid to which this level belongs |
see type |
see type |
0. |
|
|
GridLevelName |
Description for this level in the grid (e.g. Floor 1, Floor 3-mechanical, Penthouse) |
STRING |
see type |
see type |
empty string |
INV |
HasGridAxes |
Set of relationships to Grid Axes that are part of this grid level. Inverse for PartOfGridLevel |
SET [1:?] IfcGridAxis |
see type |
see type |
n/a |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
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. |
This class does not define its own reference placement, it refers to the placement in the container IfcDesignGrid.
EXPRESS Definition
Definition from IAI: Provides an abstract supertype for multiple types of constraints on placement definitions for Products, Modeling Aids and Proxys.
In R1.5, 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.
NOTE: This is a new class in IFC Release 1.5. See I-139 and IfcConstrainedPlacement for discussion.
No attributes defined in this abstract class. The class is included primarily to enhance model structure in this release.
This class is not typed -- there is no type definition.
This class has no geometry.
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 R1.5: IfcReferencePoint and IfcReferenceSurface.
NOTE: This is a new class in IFC Release 1.5.
ISSUE: See I-138, IfcReferencePoint and IfcReferenceSurface for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
ReferenceCurve |
3D geometric curve which can be used as a modeling Aid in the placement of other objects. |
see type |
see type |
Polyline from 0,0,0 to 1,1,0 |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry other than the contained 3D curve (see IfcCurve).
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.
NOTE: This is a new class in IFC Release 1.5.
ISSUE: See I-138, IfcReferenceCurve and IfcReferenceSurface for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
LocalPlacement |
Placement, relative to another object in the project |
see type |
see type |
@0,0,0 |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry.
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 R1.5: IfcReferenceCurve and IfcReferenceSurface.
NOTE: This is a new class in IFC Release 1.5.
ISSUE: See I-138, IfcReferenceCurve and IfcReferenceSurface for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
ReferencePoint |
3D geometric point |
see type |
see type |
0,0,0 |
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry other than the contained 3D point (see IfcCartesianPoint).
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 R1.5: IfcReferencePoint and IfcReferenceSurface.
NOTE: This is a new class in IFC Release 1.5. See I-138, IfcReferenceCurve and IfcReferencePoint for related discussion.
Attributes and Relationships
|
Attribute / Relation |
Definition |
Data or Relation Type |
Min |
Max |
Default |
|
ReferenceSurface |
3D geometric Surface |
see type |
see type |
Plane
|
Formal Propositions:
None |
|
This class is not typed -- there is no type definition.
This class has no geometry other than the contained 3D Surface (see IfcSurface).
