The Photometry and Colorimetry Platform characterizes the photometry (measurement of light as perceived by the human eye) and colorimetry of road and street equipment (traffic signs, road markings, etc.) and, more generally, road and urban scenes (lighting ambiences, reflections from road surfaces or urban materials, etc.).
Photometric characterization of the urban or road visual environment helps to answer research questions on the visual perception of road and street users in normal or degraded conditions (visibility, glare, visual comfort, lighting quality, photometry of road surfaces for public lighting, visual rendering in virtual reality, etc.).

The Platform comprises three main measurement benches :

The 3-axis gonioreflectometer for characterizing the reflective properties or BRDF (Bidirectional Reflectance Distribution Function) of surfaces measures variations in the coefficient of reflected luminance as a function of virtually all directions of illumination and observation of the surface of a material, particularly a road or urban surface. It provides an exhaustive characterization of a surface's reflectivity in the hemisphere above it. This test bench is currently the only one in France to enable complete characterization of road pavement surfaces, as it has been specifically designed for public lighting applications. Its measurement zone (a disc about ten cm in diameter) is large enough to take account of the macro-texture of pavements, and a mechanical and optical device keeps the measured surface fixed whatever the direction of illumination and observation.
The bench is used for research into the reflective properties of road and urban surfaces, with a view to optimizing the design of public lighting systems. It is also being adapted to measure the BRDF of wet surfaces, and to provide solutions to lighting and visibility problems in rainy conditions.

The retroreflection test bench features a motorized goniometer with 4 axes of rotation, enabling the retroreflective performance of surfaces such as signage products (microbead and microprismatic films, road markings) to be characterized. It reproduces a night-time driving situation, with a vehicle headlight illuminating the surface and the driver seated close to the direction of illumination above the headlight.  This test bench is complementary to the BRDF test bench in that it enables retroreflective geometries to be approached, which is mechanically impossible on the BRDF test bench (the sensor masks the source). The test bench is also being adapted to characterize light reflected in the specular direction in low-angled lighting (the situation of the driver observing the reflection of the headlight of the cruiser vehicle).

The colorimetric measurement bench is used to determine the colorimetric properties of surfaces by reproducing a source of daylight and measuring the spectrum of light reflected by a surface illuminated by this source at a given geometry.

Several portable or hand-held measuring devices complete the platform, such as luminance meters, spectroradiometers, colorimeters, videophotometers, light-intensity calibrated lamps and luxmeters.