IFC 4.3.0.0 (IFC4X3) final

8.14.3.8 IfcLightSourceSpot

8.14.3.8.1 Semantic definition

NOTE Definition according to ISO/IEC 14772-1:1997: The Spot light node defines a light source that emits light from a specific point along a specific direction vector and constrained within a solid angle. Spot lights may illuminate geometry nodes that respond to light sources and intersect the solid angle defined by the Spot light. Spot light nodes are specified in the local coordinate system and are affected by ancestors' transformations. Figure 8.14.3.8.A shows the definition of spot light. spot light
Figure 8.14.3.8.A — Light source spot

8.14.3.8.2 Entity inheritance

8.14.3.8.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

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.
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.
IfcLightSource (4)
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).
IfcLightSourcePositional (5)
5 Position IfcCartesianPoint

Definition from ISO/CD 10303-46:1992: The Cartesian point indicates the position of the light source. Definition from VRML97 - ISO/IEC 14772-1:1997: A Point light node illuminates geometry within radius of its location.
6 Radius IfcPositiveLengthMeasure

The maximum distance from the light source for a surface still to be illuminated. Definition from VRML97 - ISO/IEC 14772-1:1997: A Point light node illuminates geometry within radius of its location.
7 ConstantAttenuation IfcReal

Definition from ISO/CD 10303-46:1992: This real indicates the value of the attenuation in the lighting equation that is constant.
8 DistanceAttenuation IfcReal

Definition from ISO/CD 10303-46:1992: This real indicates the value of the attenuation in the lighting equation that proportional to the distance from the light source.
9 QuadricAttenuation IfcReal

This real indicates the value of the attenuation in the lighting equation that proportional to the square value of the distance from the light source.
Click to show 11 hidden inherited attributes Click to hide 11 inherited attributes
IfcLightSourceSpot (4)
10 Orientation IfcDirection

Definition from ISO/CD 10303-46:1992: This is the direction of the axis of the cone of the light source specified in the coordinate space of the representation being projected.. Definition from VRML97 - ISO/IEC 14772-1:1997: The direction field specifies the direction vector of the light's central axis defined in the local coordinate system.
11 ConcentrationExponent OPTIONAL IfcReal

Definition from ISO/CD 10303-46:1992: This real is the exponent on the cosine of the angle between the line that starts at the position of the spot light source and is in the direction of the orientation of the spot light source and a line that starts at the position of the spot light source and goes through a point on the surface being shaded.
12 SpreadAngle IfcPositivePlaneAngleMeasure

Definition from ISO/CD 10303-46:1992: This planar angle measure is the angle between the line that starts at the position of the spot light source and is in the direction of the spot light source and any line on the boundary of the cone of influence. Definition from VRML97 - ISO/IEC 14772-1:1997: The cutOffAngle (name of spread angle in VRML) field specifies the outer bound of the solid angle. The light source does not emit light outside of this solid angle.
13 BeamWidthAngle IfcPositivePlaneAngleMeasure

Definition from VRML97 - ISO/IEC 14772-1:1997: The beamWidth field specifies an inner solid angle in which the light source emits light at uniform full intensity. The light source's emission intensity drops off from the inner solid angle (beamWidthAngle) to the outer solid angle (spreadAngle).
Table 8.14.3.8.B

8.14.3.8.4 Formal representation 

ENTITY IfcLightSourceSpot
 SUBTYPE OF (IfcLightSourcePositional);
	Orientation : IfcDirection;
	ConcentrationExponent : OPTIONAL IfcReal;
	SpreadAngle : IfcPositivePlaneAngleMeasure;
	BeamWidthAngle : IfcPositivePlaneAngleMeasure;
END_ENTITY;

8.14.3.8.5 References