CIE 54.2

The report is divided into nine main sections with the following considered in detail: - Recommended terminology, including general definitions and units based on spectral quantities which are needed for characterizing the performance of retroreflectors of all types. - Additional geometric definitions and systems beside the CIE angular reference system defined in the original Publication CIE 54 - 1982. These new systems are needed largely because of new microprismatic retroreflecting materials developed since 1982 and the emphasis on the driver’s requirements at night. The road marking geometry is also included for the first time. Complete transfer equations are provided in the appendix to allow ease in converting angles between the respective systems. - The measurement of the photometric quantities section covers all techniques currently in use together with the necessary equations, reference standards and sources of uncertainty. The tolerances and effects of aperture errors are considered in detail. - A section is included which relates the angular characteristics of retroreflectors in vector notation with major emphasis on the geometry of the driving scenario. Examples of the angular relationships as a function of distance in the various geometrical systems are given for different traffic control devices, vehicles and road geometries. - The colorimetry of retroreflectors includes recent measurement techniques used for establishing the spectral quantities of retroreflection together with a recommended geometry of measurement for colorimetry under daylight and nighttime conditions. - A section is devoted to the use of portable and mobile instrumentation for the measurement of retroreflectors in the field together with recommended information on the instruments to be included in their data description. - A section dealing with recommended formats for the computer data interchange of retroreflective measurements.