Multidimensional optical diffusion for the measurement of appearance

Consumer purchase decisions are heavily influenced by the visual branding and optical appearance of products, thus increasing the importance of these values to the manufacturing process. There is currently a metrological gap in carrying out traceable and reliable measurements of the visual appearance of manufactured objects, thus creating a need to further develop visual measurement techniques. Specifically, there are requirements to establish traceable Bidirectional Reflectance Distribution Function (BRDF) measurements and develop measurement scales for translucency and mattness that align with the visual sensation. This is also in the interest of key organisations, including CIE and BIPM Consultative Committee for Photometry and Radiometry (CCPR).  Additionally, new models and parameters that assess intrinsic parameters of materials need to be develop. 

Building on the work of the EMPIR project BiRD, this project aims to develop and characterise image-based goniospectrophotometers that are able to perform traceable measurements of optical properties, including BRDF, Bidirectional Transmittance Distribution Function (BTDF) and Bidirectional Surface Scattering Reflectance Distribution Function (BSSRDF). Additionally, traceable references for BRDF, BTDF and BSSRDF that meet industry needs will be developed, as well as the generation of physical models (e.g. anisotropic surfaces or translucent materials) that have been validated against traceable measurements. Measurement scales for translucency and mattness will be developed by defining physical quantities that correlate to the visual sensation and the project partners will provide measurement protocols and good practice guides on (BRDF) measurements with a target measurement uncertainty of 5%. The project consortium will collaborate with the European Metrology Network for Advanced Manufacturing to ensure industrial uptake of these developments and improve European competitiveness in this area.