MEASUREMENTS OF THE BIDIRECTIONAL REFLECTION FUNCTION – A SYSTEM FOR THE ANALYSIS OF ROAD PAVINGS

摘要

A special goniometer is a part of a systemrnfor the measurement of the reflectionrnproperties of surfaces. The adoptedrnmeasuring procedures are based on a CCDrnluminance meter with the aim of having arngood selection of the sample under test. Inrnparticular, two methods allow thernmeasurement of the luminance coefficientrnindependently on the absolute calibration ofrnthe luminance meter; they allow thernreduction of the overall measurementrnuncertainty. The methods are based on thernratio of luminance measurement of thernsample under test and on the measurementrnof the luminance either of the light sourcernused in the test, or of a diffusing referencernsample.rnThe measures of the luminancerncoefficient, with an observation angle of 1°,rnof a white diffuse reflectance standard andrnof a road paving sample are presented asrnexamples of applications of the describedrnmethods.