IFC 4.3.x development

8.12.3.29 IfcSurfaceStyleLighting

8.12.3.29.1 Semantic definitions at the entity

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

Figure 1 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"

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 IfcColorRGB with a factor for each colour.

EXAMPLE  A green glass transmits only green light, so its transmission factor is 0.0 for red, between 0.0 and 1.0 for green and 0.0 for blue. A green surface reflects only green light, so the reflectance factor is 0.0 for red, between 0.0 and 1.0 for green and 0.0 for blue.

HISTORY  New entity in IFC2x2.

8.12.3.29.1 Attributes

#Attribute Type Description
IfcPresentationItem
IfcSurfaceStyleLighting
1DiffuseTransmissionColourIfcColourRgbThe 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.
2DiffuseReflectionColour IfcColourRgbThe 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.
3TransmissionColour IfcColourRgbDescribes 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.
4ReflectanceColour IfcColourRgbA 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.

8.12.3.29.2 Entity inheritance

dot_inheritance IfcSurfaceStyleLighting IfcSurfaceStyleLighting IfcPresentationItem IfcPresentationItem IfcSurfaceStyleLighting->IfcPresentationItem IfcPresentationItem_children 16 more... IfcPresentationItem_children->IfcPresentationItem

8.12.3.29.3 Formal representations

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