IFC 4.3.x development

8.14.3.6 IfcLightSourceGoniometric

8.14.3.6.1 Semantic definitions at the entity

IfcLightSourceGoniometric defines a light source for which exact lighting data is available. It specifies the type of a light emitter, defines the position and orientation of a light distribution curve and the data concerning lamp and photometric information.

Figure 1 shows an example of a light emitter having two light sources (of type IfcLightSourceGoniometric).

"Example"

HISTORY  New entity in IFC2x2.

8.14.3.6.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment 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.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item 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.
IfcGeometricRepresentationItem
IfcLightSource
1 Name OPTIONAL IfcLabel The name given to the light source in presentation.
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.
3 AmbientIntensity OPTIONAL 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).
4 Intensity OPTIONAL 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).
IfcLightSourceGoniometric
5 Position IfcAxis2Placement3D The position of the light source. It is used to orientate the light distribution curves.
6 ColourAppearance OPTIONAL IfcColourRgb Artificial light sources are classified in terms of their color appearance. To the human eye they all appear to be white; the difference can only be detected by direct comparison. Visual performance is not directly affected by differences in color appearance.
7 ColourTemperature IfcThermodynamicTemperatureMeasure The color temperature of any source of radiation is defined as the temperature (in Kelvin) of a black-body or Planckian radiator whose radiation has the same chromaticity as the source of radiation. Often the values are only approximate color temperatures as the black-body radiator cannot emit radiation of every chromaticity value. The color temperatures of the commonest artificial light sources range from less than 3000K (warm white) to 4000K (intermediate) and over 5000K (daylight).
8 LuminousFlux IfcLuminousFluxMeasure Luminous flux is a photometric measure of radiant flux, i.e. the volume of light emitted from a light source. Luminous flux is measured either for the interior as a whole or for a part of the interior (partial luminous flux for a solid angle). All other photometric parameters are derivatives of luminous flux. Luminous flux is measured in lumens (lm). The luminous flux is given as a nominal value for each lamp.
9 LightEmissionSource IfcLightEmissionSourceEnum Identifies the types of light emitter from which the type required may be set.
10 LightDistributionDataSourceIfcLightDistributionDataSourceSelect The data source from which light distribution data is obtained.

8.14.3.6.2 Entity inheritance

dot_inheritance IfcLightSourceGoniometric IfcLightSourceGoniometric IfcLightSource IfcLightSource IfcLightSourceGoniometric->IfcLightSource IfcLightSource_children 3 more... IfcLightSource_children->IfcLightSource IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcLightSource->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.14.3.6.3 Formal representations

ENTITY IfcLightSourceGoniometric
 SUBTYPE OF (IfcLightSource);
	Position : IfcAxis2Placement3D;
	ColourAppearance : OPTIONAL IfcColourRgb;
	ColourTemperature : IfcThermodynamicTemperatureMeasure;
	LuminousFlux : IfcLuminousFluxMeasure;
	LightEmissionSource : IfcLightEmissionSourceEnum;
	LightDistributionDataSource : IfcLightDistributionDataSourceSelect;
END_ENTITY;