The purpose of this report is to update and
replace CIE 54 - 1982 Retroreflection: Definition and Measurement.
This report is divided into nine main sections. These begin with
chapter 2 which is concerned with general definitions of
retroreflection, while chapter 3 defines geometrical terms.
Chapter 4 combines their collection into four geometric systems
applicable for different elements of the retroreflection
phenomena. Chapter 5 defines the photometric terminology as did
the original publication 54, but defines the photometric terms
with reference to spectroradiometric concepts as is the current
international standards procedure. The corresponding laboratory
calibration and measurement techniques are described in the next
section, chapter 6, together with basic instrument requirements
and traceability to national metrology laboratories. To relate the
driver's geometry to the four systems, vector notation and a
series of typical examples are given in chapter 7. This approach
will aid the transportation community in accessing the necessary
discrete angles to assure procurement compliance and the field
service life of retroreflective devices and materials. An
important section in the original publication 54, dealing with the
colorimetry of retroreflectors, is expanded in chapter 8 to
include new instrumentation presently available and to recommend
standard test geometries for both daytime and nighttime
measurements. A new section, chapter 9, describes general field
instruments available for in-situ measurements of retroreflectors.
Included in this section is a guide for manufacturers to use in
their specifications, listing important parameters of the
instruments which can be a part of the data sheet. Lastly, chapter
10 addresses the computer format for retroreflectance data in
order to allow measurement results to be exchanged world-wide.
Four appendices complete the report with all the transformation
equations between the four systems with examples, a list of
keywords, data format examples and a treatise on aperture
synthesis. The complete Technical Report consists of 58 pages with
20 figures, among them 13 coloured ones and 9 tables, and is
readily available at the CIE National Committees or the CIE
Central Bureau in Vienna.
The following members of TC 2-36
"Retroreflection: Definition and Measurement" took part in the
preparation of the report: