# 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 8.12.3.30.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.

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.

## 8.12.3.30.4 Formal representation

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