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.
|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.|
TYPE IfcLightDistributionDataSourceSelect = SELECT (IfcExternalReference ,IfcLightIntensityDistribution); END_TYPE;