Multidimensional reflectometry for industry

Short Name: xDReflect, Project Number: IND52
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Measuring complex visual effects reliably

The European automotive industry has a turnover of 900 billion euro – nearly 7 % of the EU’s GDP – with highly competitive car manufacturers vying to attract customers with stunning visual effects. Similar effects are used in printing and cosmetics, where colour, texture, gloss and sparkle drive sales. These complex surface finishes include particles and flakes to produce unique effects that depend on lighting conditions.


Instrumentation for quantifying visual effects and complex surface finishes is replacing expert inspections, providing greater consistency and efficiency in product quality control. Robust measurement methods and well-characterised reference standards are needed to improve links between human perception of complex visual effects and measurements made using instrumentation.


The EMRP Project Multidimensional reflectometry for industry, increased the accuracy of Bidirectional Reflectance Distribution Function (BRDF) measurements, used to determine quantitatively how light interacts with surfaces, and developed standards and statistical models to match measurements to our perception of complex visual effects.


The project:


  • Increased the accuracy of BRDF measurements to a resolution comparable with that of the human eye, enabling accurate optical characterisation of complex surface finishes.
  • Developed a faster method to assess visual effects using BRDF by identifying significant measurement orientations and applying new data analysis, reducing the time and complexity of measurements without sacrificing accuracy.
  • Constructed light booths for testing samples’ sparkle, iridescence and gloss under different lighting conditions, augmenting the understanding of human visual perception. This has the potential to increase the use of instrumentation in quality assurance measurements.
  • Developed a method and reference materials for measuring sparkle as a first step towards measurement standardisation and a future international documentary standard for sparkle effects.
  • Developed new approaches for the evaluation of measurement uncertainties in CIELAB colour space. The CIELAB colour space mathematically and uniquely describes all perceivable colours.


This project has increased the accuracy of instrument measurements for complex surface finishes and developed better statistical models and simulations to improve links between measurements results and our perception of complex optical effects. Project collaboration has created a unified European approach to measuring complex surface effects where each institute brings its own ethos and expertise, avoiding duplication and competition. New reference materials now provide increased SI traceability. Optical measurement calibration capabilities have been extended as a result of this project, and now cover the spectrum from the infrared to the ultraviolet. These provide improved SI traceability for instruments used in climate change studies, as well as those used for characterising materials used in solar energy cells.


A follow on EMPIR project Bidirectional reflectance definitions (BiRD) is building on XDReflect developments and is investigating increased standardisation for BRDF, sparkle, and gloss measurements and data formats. This new project aims to further improve quality assurance for complex optical effects important for the highly competitive EU industries that generate large volumes of export sales.

Project website
Other Participants
Callaghan Innovation (New Zealand)