IfcLightDistributionCurveEnum

Definition from IAI: There are three kinds of light distribution curves:

1. Type A Photometry
2. Type B Photometry
3. Type C Photometry.

The following applies (Definitions according to Standard CEN TC 169, prEN 13032-1, CIE 121 ):

1. Type A is basically not used. For completeness the Type A Photometry equals the Type B rotated 90° around the Z-Axis counter clockwise.
2. Type B is sometimes used for floodlights. The B-Plane System has a horizontal axis. B-Angles are valid from -180° to +180° with B 0° at the bottom and B180°/B-180° at the top, β-Angles are valid from -90° to +90°. (See the pictures below.)
3. Type C is the recommended standard system. The C-Plane system equals a globe with a vertical axis. C-Angles are valid from 0° to 360°, γ-Angles are valid from 0° (south pole) to 180° (north pole). (See the pictures below.)

B-Type System	C-Type Syste,

HISTORY: This is a new enumeration in Release IFC2x Edition 2.

EXPRESS specification: