The Joint Research Project “New quantities for the measurement of appearance“ will provide new traceable primary references in spectrophotometry. For more  information, please visit the project website https://bxdiff.cmi.cz/. The project will involve defining the new quantities Bidirectional Transmittance Distribution Function (BTDF) and Bidirectional Surface Scattering Reflectance Distribution Function (BSSRDF), and further improving the measurements of Bidirectional Reflectance Distribution Function (BRDF).