8.12.3.30 IfcSurfaceStyleLighting

8.12.3.30.1 Semantic definition

IfcSurfaceStyleLighting is a container class for properties for calculation of physically exact illuminance related to a particular surface style.

Figure A shows the reflection and transmission components from an incident ray. The sum of the components for reflection and transmission is a value of 1.0 denoting that the incident ray is completely decomposed into reflection and transmission components. Each value of reflection and transmission is therefore within the range 0.0 to 1.0.

material reflection components — Figure A — Surface style lighting

All these factors can be measured physically and are ratios for the red, green and blue part of the light. These properties are defined in the model as Type IfcColourRGB with a factor for each colour.

8.12.3.30.2 Entity inheritance

- IfcPresentationItem

8.12.3.30.3 Attributes

#	Attribute	Type	Description
IfcSurfaceStyleLighting (4)
1	DiffuseTransmissionColour	IfcColourRgb	The degree of diffusion of the transmitted light. In the case of completely transparent materials there is no diffusion. The greater the diffusing power, the smaller the direct component of the transmitted light, up to the point where only diffuse light is produced. A value of 1 means totally diffuse for that colour part of the light. NOTE The factor can be measured physically and has three ratios for the red, green and blue part of the light.
2	DiffuseReflectionColour	IfcColourRgb	The degree of diffusion of the reflected light. In the case of specular surfaces there is no diffusion. The greater the diffusing power of the reflecting surface, the smaller the specular component of the reflected light, up to the point where only diffuse light is produced. A value of 1 means totally diffuse for that colour part of the light. NOTE The factor can be measured physically and has three ratios for the red, green and blue part of the light.
3	TransmissionColour	IfcColourRgb	Describes how the light falling on a body is totally or partially transmitted. The factor can be measured physically and has three ratios for the red, green and blue part of the light.
4	ReflectanceColour	IfcColourRgb	A coefficient that determines the extent that the light falling onto a surface is fully or partially reflected. NOTE The factor can be measured physically and has three ratios for the red, green and blue part of the light.

Table B

8.12.3.30.4 Formal representation

ENTITY IfcSurfaceStyleLighting
SUBTYPE OF (IfcPresentationItem);
DiffuseTransmissionColour : IfcColourRgb;
DiffuseReflectionColour : IfcColourRgb;
TransmissionColour : IfcColourRgb;
ReflectanceColour : IfcColourRgb;
END_ENTITY;