IfcLightDistributionDataSourceSelect

Semantic definitions at the type

Type definition

A goniometric light gets its intensity distribution function (how much light goes in any one direction) from one of two sources: (i) an industry-standard file, (ii) from distribution data passed directly via the IfcLightIntensityDistribution.

The light distribution provides the luminous intensity distribution according to some standardized light distribution curves.

SELECT

Type	Definition
IfcExternalReference	Light distribution is represented by a standard photometric data file such as Eulumdat, IES, CIBSE TM14.
IfcLightIntensityDistribution	For representing a light distribution directly the following values needs to be given in a table like structure with column and row headings. These headings should contain the angles (C/γ or B/β ) and the table body contains the intensity values, (normally normalized to cd/Klm). The angles can be non- equidistant and the angle steps can be almost any value in the valid range, so a list of all available angles in both directions covers all cases.

HISTORY New type in IFC2x2.

Enumeration definition

Constant	Description
IfcExternalReference
IfcLightIntensityDistribution

Formal representations

XSD Specification

 <xs:group name="IfcLightDistributionDataSourceSelect">

  <xs:choice>

   <xs:element ref="ifc:IfcExternalReference"/>

   <xs:element ref="ifc:IfcLightIntensityDistribution"/>

  </xs:choice>

 </xs:group>

EXPRESS Specification


TYPE IfcLightDistributionDataSourceSelect = SELECT (

 IfcExternalReference, 
 IfcLightIntensityDistribution);
END_TYPE;


 EXPRESS-G diagram

	Light Distribution Data Source Select
	Sélection de la source de données sur la distribution lumineuse