IfcAxis1Placement

BACnet MVD

#### IfcAxis1Placement

Natural language names

| Einfügepunkt mit einer Achse
| Axis1 Placement
| Position et direction d'un axe

##### Semantic definitions at the entity

Entity definition

The IfcAxis1Placement provides location and direction of a single axis.

> Figure 311 illustrates the definition of the IfcAxis1Placement within the parent three-dimensional coordinate system.

Figure 311 — Axis1 placement

> NOTE Definition according to ISO/CD 10303-42:1992
> The direction and location in three dimensional space of a single axis. An axis1_placement is defined in terms of a locating point (inherited from placement 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 Entity adapted from axis1_placement defined in ISO10303-42.

> HISTORY New entity in IFC1.5

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
2 | Axis | IfcDirection | ? | The direction of the local Z axis. | X | X
| Z :=NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0])) | IfcDirection |  | The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.] | X | X

Formal Propositions

Rule | Description
--- | ---
AxisIs3D | The Axis when given should only reference a three-dimensional IfcDirection.
LocationIs3D | The Cartesian point defining the Location shall have the dimensionality of 3.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRepresentationItem

LayerAssignment

IfcPresentationLayerAssignment
@AssignedItems

S[0:1]

Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.

X

StyledByItem

IfcStyledItem
@Item

S[0:1]

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.

> IFC2x3 CHANGE The inverse attribute StyledByItem has been added.

X

X

IfcGeometricRepresentationItem
IfcPlacement
1 | Location | IfcCartesianPoint |  | The geometric position of a reference point, such as the center of a circle, of the item to be located. | X | X
| Dim :=Location.Dim | IfcDimensionCount |  | The space dimensionality of this class, derived from the dimensionality of the location. | X | X
IfcAxis1Placement
2 | Axis | IfcDirection | ? | The direction of the local Z axis. | X | X
| Z :=NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0])) | IfcDirection |  | The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.] | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcAxis1Placement" type="ifc:IfcAxis1Placement" substitutionGroup="ifc:IfcPlacement" nillable="true"/>
<xs:complexType name="IfcAxis1Placement">
<xs:complexContent>
<xs:extension base="ifc:IfcPlacement">
<xs:sequence>
<xs:element name="Axis" type="ifc:IfcDirection" nillable="true" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcAxis1Placement
SUBTYPE OF (IfcPlacement);
Axis : OPTIONAL IfcDirection;
DERIVE
Z : IfcDirection := NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0]));
WHERE
AxisIs3D : (NOT (EXISTS (Axis))) OR (Axis.Dim = 3);
LocationIs3D : SELF\IfcPlacement.Location.Dim = 3;
END_ENTITY;

EXPRESS-G diagram

`

References: IfcRevolvedAreaSolid IfcSurfaceOfRevolution

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