Publishable JRP Summary Report for JRP IND52 xD-Reflect
Multidimensional reflectometry for industry
M12
Objects that have identical shapes are mainly identified through their visual attributes. These attributes are
colour, gloss, texture, and transparency. Thanks to its visual experience, the observer by compiling these
attributes produces the appearance of the object.
The appearance of a product is important for nearly all industrial sectors, like for instance automotive,
cosmetics, paper, printing, packaging, coatings, plastics, and this for two main reasons. First, the
appearance informs the manufacturer on the quality, the control and the reproducibility of its production. In
the leather or in the glass industries for instance, most of the quality control is done by visual observation.
Second, the appearance of a product touches directly the customer and is a critical parameter implicated in
the choice. For this reason, within the last 20 years, a lot of effort has been undertaken by industrial
manufacturers to develop new and sophisticated visual effects, by use for instance of metallic paint,
goniochromatic pigments, deep matt finishes, fluorescence agent, sparkle or other nacre or grainy effects.
To characterize these effects, a panel of instruments is available, working usually in relative mode, by
comparison of the sample's signal against a standard.
National Metrological Institutes (NMI) offer, in order to ensure the traceability of the industrial measurement
facilities, standards and artefacts. But unfortunately, these are limited to the visual effect they generate. For
instance, in the field of colorimetry, the artefacts used are uniform colour tiles or white pressed powders and
only two standard angular configurations are standardized. Obviously, this situation is insufficient and not
adapted to characterize actual effects, like metallic colours, or interferential pigments that make the colour
change according to direction of observation. The situation is the same for the other visual attributes like for
gloss, where the measurement standard used by the glossmeter is useful in monitoring the day-to-day
quality of a product, but is inadequate for other requirements as simple as describing the gloss level under
different illuminations, or between different coloured samples. Another example concerns the fluorescence,
where the calibration methods are copied from the non-fluorescent methods and lead to inaccurate data. All
this gives the impression that the special effect pigments industry and its derived sectors progress faster
than the measurement standards institutions and force the industrial to develop their own references
standards or equipments, with a lost of traceability.
From a metrological point of view, in this field, the relevant quantity is the Bidirectional Reflectance
Distribution Function (BRDF), that is the ratio of the radiance taken in one given direction, by the irradiance
coming from another direction, at a given wavelength. The BRDF is measured with a
goniospectrophotometer and provide a full characterisation of the light reflected by the sample.
The project xDReflect aims to improve the primary metrology in the field of material characterisation, in order
to provide new measurement protocols and new standard artefacts that will permit to industrials to control
the visual appearance of the surfaces they produce today. These measurements, to be easily exploitable,
must correlate as much as they can to the human visual sensation.
In order to reach this objective, the JRP has oriented its action on 4 main axis:
•
Improvement of primary goniospectrophotometers in order to progress in BRDF measurement and
reduce the measurement uncertainty.
•
Development of models for data compression, data representation and data handling for BRDF
measurement
•
Understanding of correlation between the visual appearance and the BRDF
•
Developing standard procedures and transfer artefacts in order to develop applied metrology for
visual appearance attributes.
Report Status: PU
Public
Publishable JRP Summary
P1 of 4
Issued: January 2015r
Among the different visual attributes, the JRP consortium has decided to restrict its action on color, gloss
and fluorescence. Transluscency and texture can not be addressed. This choice has been made to optimize
the effienciency of the reseach and the ressources available for the project.
At short term, the results are expected to have an impact for the European industries by:
•
Encouraging the industry to develop new measurement devices in the field of reflectometry and
visual effect characterisation, like for instance iridescence, gloss, fluorescence, sparkle and graininess.
•
Achievement of accurate and stable measurements, traceable to NMI references providing
improvements in quality control during the production process.
•
Providing objective and scientific means of checking that specifications have been met (instead of
using subjective expert judgements) and therefore improving client-supplier relations and ability to deliver.
•
Reducing the costs in production thanks to a better knowledge of the border between “the things that
are seen” and “the things that are not seen”, allowing the manufacturer to know more accurately where he
has to put its effort in the production, in order to increase the visual quality of its goods.
Put together, these contributions are expected to stimulate the development of new visual effects and to
reduce the cost of production that will improve the competitiveness of the EU industry in the world.
Progress :
The project xDReflect has started on 1st Sept 2013.
During the first semester, an important energy has been devoted to find or develop the samples that will be
at the basis of the future measurement tasks. In WP1 (goniochromatism), dedicated matt ceramic tiles have
been purchased and appropriate high quality reflection standards have been produced for the future
comparison of primary goniospectrophotometers of the consortium. At the same time, 500 samples from
different automotive and coatings companies have been collected in order to have a good overview of what
is state of the art of the industrial know-how in the field. In WP2 (gloss), a gloss scale has been constructed
thanks to a close collaboration with St Gobain Research, industrial stakeholder of the project. In WP3
(Fluorescence), the samples for the inter comparison have been selected. A new organization REG,
Innventia (Sweden) has jointed the consortium in January 2014 as REG3. His action will be focused on the
adjustment of UV content in the light source of fluorescence measurement devices and on the construction
of new fluorescence standard artefacts. At the same time, the work has started on the different
goniospectrophotometer in the consortium in order to reduce the level of uncertainty and to be ready to start
the different comparisons. The travel of the samples between the participants has been agreed for the WP1,
WP2 and WP3 in order to avoid conflict of schedules.
The second semester has been dedicated to measurements. The comparison of the gonioreflectometers is
running and already five of the eight participants have completed the measurements. Specular peaks of the
gloss scale, effects pigments, fluorescents standards artefacts have also been measured. In each of the
three technical workpackage, it means hundreds of hours of measurements done. At the same time, a new
mathematical approach for BRDF representation, based on the visual sensation, have been proposed.
Every 6 months, the consortium presents its progress to the stakeholders of the project during 2 days
progress meetings. In February 2014, the meeting was held in Braunschweig (Germany). 31 persons
attended and 13 of them were from industries. In December 2014, the meeting was in Alicante (Spain). 38
persons attended in total, 18 were from industries. In between, the consortium met in St Denis (France) and
in Espoo (Finland). This high frequency of meeting ensures a close collaboration between the partners, and
a real share of experience between the consortium and the stakeholders.
Since the first month of the project, the xDReflect website (http://www.xdreflect.eu/) is active. The visitor can
find here detailed information on the project, pictures of the facilities and of the samples and news. Technical
information, measurement results are shared with the collaborators in a restricted area.
Publishable JRP Summary
- P2 of 4 -
Issued: January 2015
JRP start date and duration: 1 Sept 2013, 36 months
JRP-Coordinator:
Gaël Obein, Dr, CNAM,
Tel: +33 1 78808788
JRP website address: http://www.xdreflect.eu/
JRP-Partners:
Conservatoire national des arts et metiers, CNAM,
France
Cesky Metrologicky Institut Brno,CMI, Czech Republic
E-mail: gael.obein@cnam.fr
JRP-Unfunded Partners:
Callaghan Innovation, CIRL, New Zealand
Agencia Estatal Consejo Superior de Investigaciones
Cientificas , CSIC, Spain
Istituto Nazionale di Ricerca Metrologica, INRIM, Italy
Mittatekniikan Keskus, MIKES, Finland
Physikalisch-Technische Bundesanstalt, PTB, Germany
Sveriges Tekniska Forskningsinstitut AB, SP, Sweden
REG-Researcher
(associated Home Organisation):
Katholieke Universiteit Leuven, KUL, Belgium
University of Alicante, UA, Spain
Innventia, Innventia, Sweden
The EMRP is jointly funded by the EMRP participating countries within EURAMET and the
European Union
Publishable JRP Summary
- P3 of 4 -
Issued: January 2015
Publishable JRP Summary
- P4 of 4 -
Issued: January 2015