Gael OBEIN - english version

Gaël Obein

   Associate Professor
   PhD in « Metrology and Physical Systems »


Lab level

  • Director of LNE-CNAM, French designated institute for Length, Temperature, Radiometry and Photometry
  • Head of Radiometry/Photometry Team
  • Head of « Photometry/Spectrophotometer » calibration service

National level

  • President of Association Française de l’Éclairage (AFE)
  • National delegate at CIE division 2 (measurement of light)
  • Contact person for key comparisons at CCPR and Euramet-TC-PR level
  • Member of supervisory board of GDR CNRS 2044 APPAMAT

International level

  • Division secretary CIE Div2
  • Co -chair of CIE Joint Technical Committee JTC17 (D1/D2/D8)
  • Member of 4 CIE Technical committee (TC2-81, TC2-77, JTC12)
  • Coordinator of key comparison EURAMET-PR-K6 (regular transmittance, 18 participants)
  • Coordinator of EU funded research projects :

       xDreflect       BiRD    Logo BxDiff

Sep 2013 – Aug 2016           Apr 2017 – Ma r2020           May 2019 – Apr 2022

"xDReflect", JRP IND52 – Multidimensional Reflectometry for Industry

UE funded project in the frame of EMRP program, 36 month, 10 partners, 2.9 M€

Project objectives were:

  • Improvement of primary metrology in the field of goniospectrophotometry (BRDF measurement)
  • Proposal of new solutions for the characterization of goniochromatism, gloss, sparkle and fluorescence
  • Proposal of new transfer artefacts for these 4 visual attributes.

"BiRD", JRP 16NRM08 – Bidirectional Reflectance Definitions

UE funded project in the frame of EMPIR, 36 months, 11 partners, 536 k€.

Project objectives are:

  • Initiate a normative work on how BRDF measurements have to be done in order to properly characterize goniochromatism, gloss and sparkle
  • Propose a universal data arrangement of BRDF measurement files.

"BxDiff ", JRP 19SIB03 – New quantities for the measurement of appearance

UE funded project in the frame of EMPIR, 36 months, 17 partners, 1,6 M€.

Project objectives are :

  • To address last issues about BRDF measurements (polarization, speckle, measurements on tiny objects)
  • To develop and compare NMI's metrological scales for BTDF
  • To develop primary facilities for BSSRDF measurements
  • To develop, select or promote a new generation of standard artefacts to transfer the scales to industry.

Activité de recherche

“Mise en pratique” of photometry and spectrophotometry primary references
  • Improvement of facilities in order to reduce measurement uncertainties and keep the French metrology at the highest level for photometry and spectrophotometry.
  • Coordinator and/or participant in key comparison at CCPR level and Euramet-PR level.
« Metrology of appearance »
  • Development and validation of the primary scale for the measurement of the Bidirectional Reflectance Distribution Function (BRDF) by design, implementation and characterization of a goniospectrophotometer
  • Development of a facility allowing the measurement of the BRDF of glossy surfaces, with an angular resolution of 0.015° (better than the human visual system)
  • Development of facilities devoted to the measurement of µBRDF (illuminated surface of 50 µm diameter) and devoted to BSSRDF measurement.


  • since 2006 Associate professor at the Conservatoire National des Arts et Métiers, Paris.
  • 2005 – 2006 Post-doc at the Conservatoire National des Arts et Métiers, Paris., Paris.
  • 2004 – 2005 Post-doc at National Institute of Standards and Technology (NIST), USA
  • 2002 – 2004 Assistant Professor at University Pierre and Maire Curie (Paris VI).
  • 1999 – 2003 PhD student at Muséum National d’Histoire Naturelle, under the advisory of Prof. F. Viénot
  • 1998 – 1999 MSC in Metrology, Laser and Telecommunication at University Paris 13
  • 1997 – 1998 Military duty
  • 1995 – 1997 BSC in Physics


  • Gozhyk I., Turbil C., Garcia E., Obein G., 2023, “Impact of light polarization on angle-resolved light scattering from gloss scale” Physica Scripta 98(9)
  • Khlevnoy B, Solodilov S., Kolesnikova S., Otryaskin D., Pons A., Campos J., Shin D, Park S., Obein G., Valin M., Vissière A., Dai C., Wu Z., Wang Y., Li L., Lin Y., Yoon H., Gibson G., Liu Y., Manson P., Atkinson E., Zama T., Shitomi H., Goodman T., Servantes W., Gamouras A., Woods W., Sperfeld P., Pape S., 2023, “CIPM key comparison CCPR-K1.a.2017 for spectral irradiance 250 nm to 2500 nm. Final report ”, Metrologia, 60(1A)
  • Molloy E., Koo A., Gevaux L., Obein G., Yang L., 2023, “Use of bidirectional transmittance distribution function measurements to determine transmittance haze ”, Metrologia, 60(5)
  • Gevaux L., Dupiau A., Morvan K., Obein G., 2023, “The Measurement of Specular Gloss using a Conoscopic Goniospectrophotometer”, London Imaging Meeting, 2023, pp 10-14
  • Ansari-Asl M., Barbieri M., Obein G., Hardeberg J., 2023, “Advancing Material Appearance Measurement: A Cost-effective Multispectral Imaging System for Capturing SVBRDF and BTF”, London Imaging Meeting, 2023, pp 104-108
  • Obein G., 2023, “Physics and Measurement of properties linked to appearance”, London Imaging Meeting, 2023, pp1-4
  • Gevaux L., Saha D., Obein G., 2023, “Investigating the optical translucency of Spectralon using BSSRDF measurements”, Applied Optics, 62(18)
  • Basic N., Molloy E., Koo A., Ferrero A., Santafé Gabarda P., Gevaux L., Porrovecchio G., Schirmacher A., Šmíd M., Blattner P., Hauer K.-O., Quast T., Campos J., Obein G., 2023, “Intercomparison of bidirectional reflectance distribution function measurements at in- and out-of-plane geometries”, Applied Optics, 62(13), 3320-3329
  • Lafitte A. , Sordello R., Legrand M., Nicolas V., Obein G. , Reyjol Y., 2022, “A flashing light may not be that flashy: A systematic review on critical fusion frequencies”, Plos one 17(12) : e0279718
  • Gaertner A., Côté E., Campos J., Obein G., Blattner P., Schafer R., Hui L., Xiaomei J., Miller C., Zong Y., Atkinson E., Thorvaldson E., Kinoshita K., Sieberhagen R., Rabe I., Goodman T., Scott B., Sperling A., Lindner D., KhlevnoyB. & Ivashin E., 2022, “Final report on the CCPR Key Comparison CCPR-K3.2014 Luminous Intensity”, Metrologia, 59
  • Valin M. H., Obein G., Rougie B., Valin T., Truong D., Vissiere A., Bourson, 2022, “New traceability chain for spectral irradiance measurement at LNE-Cnam”, Measurement Science and Technology, 33(6)
  • Chavel P., Sortais Y., Labardens T., Simonot L., Hébert M., Obein G., 2022, “Advocating a statistical definition for the BRDF”, Journal of Physics: Conference Series, 2149(2022)
  • Valin M. H., Obein G., 2021, "A new method for measuring the spectral irradiance at LNE-CNAM", Proceedings of the 20th International Congress of Metrology (CIM 2021), 7-9 September 2021, Lyon, France
  • Obein G., 2021, "The measurement of appearance", Proceedings of the International School of Physics "Enrico Fermi", Vol 206 : New Frontiers for Metrology: From Biology and Chemistry to Quantum and Data Science, IOP Press, pp 175 - 186
  • Valin M. H., Rougié B., Vissiere A., Obein G., Valin T., 2021, "New spectral irradiance traceability scale at LNE-CNAM", Proceedings of NewRad 2021
  • Chavel P., Labardens T., Hébert M., Simonot L.,Sortais Y., Obein G., 2021, “Evidence for the need to update the definition of the BRDF - spectral considerations”, Proceedings SPIE Volume 12126,
  • Saha D., Gevaux L., Cances T., Richard A., Obein G., 2021, “Development of a µBRDF goniospectrophotometer for BRDF measurement on tiny surfaces”, Proceedings of CIE2021
  • Labardens T., Chavel P., Sortain Y., Hébert M., Simonot L.., Obein G., 2021, “Study and simulations of speckle effects on BRDF measurements at very high angular resolution”, Proceedings of the IS&T Electronic Imaging Symposium, Material Appearance 2021, Jan 2020, (link)
  • P. Chavel, T. Labardens, L. Simonot, M. Hébert, Y. Sortais & G. Obein, 2021, "Speckle in BRDF measurements: solid angle considerations," in Frontiers in Optics + Laser Science 2021, Technical Digest Series (Optica Publishing Group, 2021), paper JTh5A.76.
  • Rabal A., Ged G., Richard A., Obein G., 2020, “Effect of the size and shape of the measurement area on BRDF measurements on glossy samples”, Proceedings of the International Colour Association (AIC) Conference 2020, Avignon, Nov 2020, pp 384-388 (link)
  • Ged G., Rabal A. M., Himbert M., Obein G., 2020, “Assessing gloss under diffuse and specular lighting”, ColorResearch & Application, 45(6), pp 591-602 (10.1002/col.22510)
  • Simonot L., Obein G., Bringier B., Meneveaux D., 2019, “Modeling, measuring, and using BRDFs: significant French contributions”, JOSAA, 36(11):C40
  • Balasse M., Tresset A., Obein G., Fiorillo D., Gandois H., 2019, “Seaweed-eating sheep and the adaptation of husbandry in Neolithic Orkney: new insights from Skara Brae”, Antiquity, 93(370), pp 919-932
  • Obein G., 2019, “Measurement of appearance;  optical, visual and normative approach”, Proceedings of “Procédés laser pour l’industrie conference”, 25-26 Sept, Colmar, France, 3 pages
  • Rabal A. M., Ged G., Obein G., 2019, “What is the true width and height of the specular peak according to the level of gloss ?”, Proceedings of the 29th Quadriennal Session of CIE, CIE x046:2019, OP88
  • Obein G., 2019, “Le goniospectrophotomètre : principe, performances et limitations”, in Simonot L. et Boulenguez P., Quand la matière diffuse la lumière, Presses des Mines, 2019, pp. 71-90
  • Simonot L., Chavel P., Hebert M., Obein G., 2019, “Peut-on mesurer la BRDF”, in Simonot L. et Boulenguez P., Quand la matière diffuse la lumière, Presses des Mines, 2019, pp. 439-452
  • Ged G., Obein G., Rabal A. M., 2019, “Du brillant à la BRDF”, in Simonot L. et Boulenguez P., Quand la matière diffuse la lumière, Presses des Mines, 2019, pp. 209-220
  • Obein G., 2019, “Traceability and references for the measurement of appearance : review of latest developments at Europeans national metrological institutes”, Proceedings of “Cosmetic Measurement & Testing Conference, 3rd edition”, Feb 2019, Gergy, France, 3 pages
  • Dubard J., Obein G., Suryani D., 2019, “Bilateral comparison of luminous flux using lamps as transfer standards (EURAMET.PR-K4.2)”, Metrologia, 56(1A) , Tech. Suppl., 02001

  • Ged G., Obein G.,  Himbert M., Turbil C., Rabal A. M.,  2017, “Does the visual system extracts more information than gloss in the specular direction?”, Proceedings of the Conference at the CIE Midterm Meeting, CIE x044:2017, p.396-403.
  • Ged G., Rabal A. M., Obein G., 2017 “Absolute BRDF measurements with ultra-high angular resolution for the characterization of optical surfaces”, 2017, NEWRAD 2017 Proceedings, Tokyo, Japan.
  • Obein G., Simionescu M., Dubard J., Seucan A., Bastie J., 2017, “Luminous intensity bilateral comparison using lamps as transfer standards between LNE (France) and INM-RO (Roumania)”, Metrologia, 54, Tech. Suppl., 02003.
  • Page, M., Obein, G., Boust, C., & Razet, A. , 2017, “Adapted Modulation Transfer Function Method for Characterization and Improvement of 3D printed surfaces”, Electronic Imaging, 2017(8), 92-100.
  • Turbil C., Gozhyk I., Teisseire J., Obein G., Ged G., 2016, “Predicting changes in visual appearance of periodic surface from BRDF measurements”, Proceedings of 4th CIE Expert Symposium on Colour and Visual Appearance, Prague, CZ.
  • Page M., Boust C., Mélard N., Robcis D., Obein G., Ortiz Segovia M., 2016, “3D surface acquisition : Comparison of two microtopographic equipments when measuring materials of cultural heritage”, Proceedings of 4th CIE Expert Symposium on Colour and Visual Appearance, Prague, CZ.
  • Strothkämper C., Ferrero A., Koo A., Jannson P., Ged G., Obein G., Källberg S., Audenaert J., Leloup F., Verdu F., Perales E., Schirmacher A., Campos J., 2016, “Multilateral Spectral Radiance Factor Scale Comparison”, Applied Optics, 56(7), p1996-2006,
  • Leloup F., Audenaert J., Obein G., Ged G., Hanselaere P., 2016, "Repeatability and reproducibility of specular gloss meters in theory and practice", J Coat Technol Res. 13: 941
  • Ged G., Leloup F., De Wit Y., Obein G., 2016, “Intercomparison of visual gloss psychometric scales”, Proceedings of 4th CIE Expert Symposium on Colour and Visual Appearance, Prague, CZ.
  • Cooksey C., Obein G., Georgiev G., Durell C., Scharpf D., McKee G., L'Heureux M., 2015, Creation and Validation of Spectralon BRDF Targets & Standards, Proceedings of SPIE Vol 9639-49, 12p.
  • Ged G., Flys O., Silvestri Z., Källberg S., Tayeb-Chandoul F., Le Breton R., Himbert M., Obein G., 2015, Characterizations of specular peaks from a metrological gloss scale, Proceedings of 28th CIE Session, Manchester, UK, 344 - 354
  • Le Breton R., Ged G., Obein G., 2015, Out of plane BRDF measurement at LNE-Cnam using "ConDOR" our primary goniospectrophotometer, Proceedings of 28th CIE Session, Manchester, UK, 1401 – 1407.
  • Obein G., Audenaert J., Ged G., Leloup F., 2015, Metrological issues related to BRDF measurements around the specular direction in the particular case of glossy surfaces', Measuring, Modeling, and Reproducing Material Appearance, Proceedings of SPIE Vol. 9398, 8 February, San Francisco, USA.
  • Ged G., Teisseire J., Garre E., Himbert M., Obein G., 2014, 'Development of a controled metrological gloss scale', NEWRAD 2014 proceedings, Espoo, Finland.
  • Comard, A., Baret, F., Obein, G., Simonot, L., Meneveaux, D., Viénot, F., de Solal, B., 2014, ACT: A leaf BRDF model taking into account the azimuthal anisotropy of monocotyledonous leaf surface, Remote Sensing of Environment, 143, 112–121.
  • Obein G., 2014, 'xDReflect, a European Joint Research Project devoted to the metrology of the appearance of surfaces', ISCC Bridge Session at Color, Light & Appearance Week at NIST, June, Gaithersburg, USA.
  • Höpe A., Koo A., Forthmann C., Verdú F.M., Manoocheri F., Leloup F., Obein G., Wübbeler G., Ged G., Campos J., Hauer K-O., Yang L., Šmíd M., Langovoy M., Iacomussi P., Jaanson P., Källberg S., 2014, 'xD-Reflect - "Multidimensional Reflectometry for Industry" a research project of the European Metrology Research Program (EMRP)', NEWRAD 2014 proceedings, Espoo, Finland.
  • Obein, G., Ouarets, S., Ged, G., 2014, Evaluation of the shape of the specular peak for high glossy surfaces (invited paper), Measuring, Modeling, and Reproducing Material Appearance, Proceedings of SPIE Vol9018., 4-5 February, San Francisco, USA.
  • Höpe, A., Koo, A., Verdu, F., Leloup, F., Obein, G., Wübbeler, G., Campos, J., Iacomussi, P., Jaanson, P., Källberg, S., Šmíd, M., 2014, "Multidimensional Reflectometry for Industry" (xD-Reflect) an European research project, Measuring, Modeling, and Reproducing Material Appearance, Proceedings of SPIE Vol. 9018, 4-5 February, San Francisco, USA.
  • Leloup, F., Obein, G., Pointer, M., Hanselaer, P., 2013, Toward the soft metrology of surface gloss: A review. Color Res. Appl.. doi: 10.1002/col.21846
  • Ouarets, S, Leroux, T., Rougie B., Razet, A., Obein G., 2013, A high resolution set up devoted to the measurement of the Bidirectional Reflectance Distribution Function around the specular peak, at LNE-CNAM, Proceedings of Metrologie 2013, octobre 2013, Paris
  • Balasse M., Obein G., Ughetto-Monfrin J., Mainland I., 2012, Investigating seasonality and season of birth in past herds: a reference set of sheep enamel stable oxygen isotope ratios, Archaeometry, 54, 2, p 349-368.
  • Ouarets, S., Ged, G., Razet, A., Obein, G., 2012, A new gonioreflectometer for the measurement of the bidirectional reflectance distribution function (BRDF) at LNE-CNAM, Proceedings of CIE 2012 “lighting quality and energy efficiency”, p687-691, 19 - 21 September 2012, Hangzhou, China
  • Obein G., Bastie J., Škerovic V., Vukadin P.,2011, Report on the bilateral comparison between ZMDM (Serbia) and LNE-INM (France) (Euramet Project 766) EURAMET.PR-K6.1: Spectral regular transmittance, Metrologia, 48, Tech. Suppl., 02003
  • Obein G., Bastie J., 2011, Report on the key comparison EUROMET-PR-K6: Spectral regular transmittance, Metrologia, 48, Tech. Suppl., 02002
  • Obein G., 2011, Le brillant du noir, Ecole thématique interdisciplinaire CNRS, Le noir et le blanc, Okhra, Roussillon, p 127-141.
  • Ged G., Obein G., Viénot F., 2011, Assessing material visual gloss – Evaluer le brillant visuel d’un matériau, 15ème Congrès International de Métrologie, octobre 2011, Paris, France, 6 pages.
  • Ged G., Obein G., Silvestri S., Le Rohellec J., Viénot F., 2010, recognizing real materials from their glossy appearance, Journal of vision, 10 (9)18.
  • Obein G., Ged G., Richard A., 2010, A new gonioreflectometer dedicated to the measurement of the appaearance of materials at the LNE-Cnam, 2nd CIE Expert symposium on Appearance, 8-10 septembre, Gand, Belgique.
  • Pousset N., Obein G., Razet A., 2010, Visual experiment on LED lighting quality with “Color quality scale” colored samples, CIE 2010 : « Lighting quality and energy efficiency », 14-17 mars 2010, Vienne, Autriche
  • Obein G., Bastie J., 2009, Report on the CCPR Key Comparison K6: Spectral regular transmittance, Metrologia, 46, 02002
  • Nadal, M, Obein, G., 2008, NIST goniospectrometer for surface color measurements, Proceedings of the CIE Expert Symposium on advances in Photometry and Colorimetry, CIE publication x033:2008, 134-138 (2008)
  • Simonot, L., Obein, G., 2007, Geometrical considerations in analyzing isotropic or anisotropic surface reflections, Appl. Opt. 46, 2615-2623
  • N. Pousset, A. Razet, G. Obein, A. Richard, J. Bastie, 2007, Métrologie des diodes électroluminescentes, actes des conférences métrologie 07, éditions poisson-soluble (ISBM : 2-915416-06-0), 13ème congrès international de métrologie, 18-21 juin 2007, Lille, France
  • Razet A., Pousset N., Obein G., Bastie J., Vienot F., 2007, Métrologie de l'apparence, Actes des conférences Métrologie 07, éditions poisson-soluble (ISBN : 2-915416-06-0), 13ème Congrès international de métrologie, 18-21 juin 2007, Lille, France
  • Obein, G., Gonzalez-Galvan, L., Bastie, J., 2007, A new realization of the candela at the Lne-Inm/Cnam, Proceedings of the 26th session of the CIE, Vol. 1, part. 1,  pp192-195.   
  • Obein, G., Gonzalez-Galvan, L., Bastie, J., 2007, Nouvelle réalisation de la candela au LNE-INM/CNAM, revue française de métrologie, 12, p19-28.
  • Obein, G., Vienot, F., 2007, Modelling the BRDF of a series of matt to glossy black samples, Proceedings of the CIE Expert Symposium on Visual Appearance, CIE publication x032:2007, 67-74 (2007)
  • Obein G., Bousquet R, Nadal M., 2005, New NIST Reference Goniospectrometer, Optical Diagnostics, Proceedings of SPIE Vol. 5880, 31 July – 4 August, San Diego, USA, pages T1-T10.
  • Nadal M., Bousquet R., Obein G., 2005, NIST Reference Colorimeter, AIC Colour 05 Proceedings, 10th Congress of the International Colour Association, Grenada, 701-704.
  • Obein G., Pichereau T., Harrar M., Monot A. , Knoblauch K. & Viénot F., 2004, Does binocular vision contribute to gloss perception?, Journal of Vision, 4(11).
  • Obein G., Knoblauch K., Viénot F., 2004, Difference scaling of gloss: Nonlinearity, binocularity, and constancy. Journal of Vision, 4(9), 711-720.
  • Viénot, F. , Obein, G., 2004, Is gloss recognized as a surface property?, Proceedings of MS 2004, 1st International Workshop on Materials and Sensations, Pau, France, 27-29 October 2004, pages 77-82
  • Obein G., Leroux T., Knoblauch K., Viénot F., 2003, Visually relevant gloss parameters, Proceedings of 11th international Metrology congress, Toulon, 20-23 octobre 2003, 6p.
  • Obein G., Vienot F., 2003, Rapport de contrat pour le Bureau National de Métrologie, contrat MNHN 0465 – BNM 003005.
  • Obein G., Knoblauch K., Chrisment A., Viénot F., 2002, Perceptual scaling of the gloss of a one-dimensional series of painted black samples, 25th European Conference on Visual Perception, August 25-29, Glasgow, UK, Perception, vol 31, p 63.
  • Obein G., Leroux T., Viénot F., 2002, Gloss & BRDF, Reconstructing the BRDF from a limited number of measurements, Inter Society of Color Council, Symposium on Appearance & Color, 21-23 April 2002, Pontiac, USA.
  • Viénot F., Monot A., Obein G., 2001, Sensation visuelle : Effets de moirés, de brillant, de lustre et de transparence, Colloque «Jouer la lumière : le textile, la lumière et l’œil », Musée de la mode et du textile / Union centrale des arts décoratifs, 12-13 novembre, Paris, 12 pages.
  • Obein G., Leroux T., Viénot F., 2001, Bi-directional reflectance distribution factor and gloss scales, Human vision and electronic imaging VI, proceedings of SPIE, vol 4299, 22-25 January 2001, San Jose, USA  pages 279-290.
  • Obein G., Leroux T., Viénot F., 2000, Variability of the 3d repartition of haze with the incident beam geometry. First international Conference on Color Graphics and Image Processing, October 1-4, 2000, Saint-Etienne, France. Pages 296-299.
  • Obein G., Domont S., Brettel H., Viénot F., 2000, Contrast appearance under mesopic adaptation. A comparison between a simulation and the reality. NPL Colour and Visual Scales 2000, 3-5 April 2000, Egham, GB, 4 pages.