IfcLightSource

BACnet MVD

#### IfcLightSource

Natural language names

| Lichtquelle
| Light Source
| Source de lumière

##### Semantic definitions at the entity

Entity definition

> NOTE Definition according to ISO 10303-46:
> The light source entity is determined by the reflectance specified in the surface style rendering. Lighting is applied on a surface by surface basis: no interactions between surfaces such as shadows or reflections are defined.

> NOTE Entity adapted from light_source defined in ISO 10303-46.

> NOTE In addition to the attributes as defined in ISO10303-46 the following additional properties from ISO/IEC 14772-1:1997 (VRML) are added: ambientIntensity and Intensity. The attribute Name has been added as well (as it is not inherited via representation_item).

> HISTORY New entity in IFC2x, renamed and enhanced in IFC2x2.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | Name | IfcLabel | ? | The name given to the light source in presentation. |  | X
2 | LightColour | IfcColourRgb |  | Definition from ISO/CD 10303-46:1992: Based on the current lighting model, the colour of the light to be used for shading. Definition from VRML97 - ISO/IEC 14772-1:1997: The color field specifies the spectral color properties of both the direct and ambient light emission as an RGB value. |  | X
3 | AmbientIntensity | IfcNormalisedRatioMeasure | ? | Definition from VRML97 - ISO/IEC 14772-1:1997: The ambientIntensity specifies the intensity of the ambient emission from the light. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity). |  | X
4 | Intensity | IfcNormalisedRatioMeasure | ? | Definition from VRML97 - ISO/IEC 14772-1:1997: The intensity field specifies the brightness of the direct emission from the ligth. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity). |  | X

##### 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
IfcLightSource
1 | Name | IfcLabel | ? | The name given to the light source in presentation. |  | X
2 | LightColour | IfcColourRgb |  | Definition from ISO/CD 10303-46:1992: Based on the current lighting model, the colour of the light to be used for shading. Definition from VRML97 - ISO/IEC 14772-1:1997: The color field specifies the spectral color properties of both the direct and ambient light emission as an RGB value. |  | X
3 | AmbientIntensity | IfcNormalisedRatioMeasure | ? | Definition from VRML97 - ISO/IEC 14772-1:1997: The ambientIntensity specifies the intensity of the ambient emission from the light. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity). |  | X
4 | Intensity | IfcNormalisedRatioMeasure | ? | Definition from VRML97 - ISO/IEC 14772-1:1997: The intensity field specifies the brightness of the direct emission from the ligth. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity). |  | X

##### Formal representations

XML Specification
`<xs:element name="IfcLightSource" type="ifc:IfcLightSource" abstract="true" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcLightSource" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem">
<xs:sequence>
<xs:element name="LightColour" type="ifc:IfcColourRgb" nillable="true"/>
</xs:sequence>
<xs:attribute name="Name" type="ifc:IfcLabel" use="optional"/>
<xs:attribute name="AmbientIntensity" type="ifc:IfcNormalisedRatioMeasure" use="optional"/>
<xs:attribute name="Intensity" type="ifc:IfcNormalisedRatioMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcLightSource
ABSTRACT SUPERTYPE OF(ONEOF(IfcLightSourceAmbient, IfcLightSourceDirectional, IfcLightSourceGoniometric, IfcLightSourcePositional))
SUBTYPE OF (IfcGeometricRepresentationItem);
Name : OPTIONAL IfcLabel;
LightColour : IfcColourRgb;
AmbientIntensity : OPTIONAL IfcNormalisedRatioMeasure;
Intensity : OPTIONAL IfcNormalisedRatioMeasure;
END_ENTITY;

EXPRESS-G diagram

`

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