Workshop on BRDF, BTDF and BSSRDF Models

DFM with support from DTU and KU Leuven organized a workshop on the use of BRDF, BTDF and BSSRDF models developed within the project for the project partners and other interested parties in the stakeholder community. 25 persons met on 28 September in Hørsholm and 24 attended the workshop online.

Presentations from the workshop will be made available on the Stakeholders space of BxDiff website later.

New stakeholder PhotonLyX

PhotonLyX has joined the BxDiff group as stakeholder! PhotonLyX®® ®has been founded in 2013 at Santander, Cantabria, Spain. The company is dedicated to consulting, creation of new optical instrumentation and  computer modelisation. We work essentially for cosmetic industry, food industry and health applications. We are specially interested in physico-chemical analysis and visual appearance of materials. We have a strong research activity about light-matter interaction, light scattering in materials volume, Monte-Carlo simulations. We lead the community around a free software for volume light scattering based on Monte-Carlo algorithm, available at Contact: Laurent Brunel. Web:

Best student paper award at CVCS 2022

BxDiff project member Jinglin Fu (PTB) won the best student paper award at the 11th Color and Visual Computing Symposium, Sept. 8-9, 2022 in Norway!

The paper reported on the measurement results from PTB in the comparison carried out within BxDiff, together with some simulation results, performed by Jeppe Revall, explaining the wavelength dependence of the samples.

Optical diffusers are used in many application areas related to illumination. With the purpose of characterizing the transmission properties of optical diffusers, we present preliminary results of BTDF (Bidirectional Transmittance Distribution Function) measurement with high angular resolution at two different wavelengths. The expanded total uncertainty of the measurement is estimated to be 0.5% in the best case. In this way, the scattering distribution of optical diffusers could be quantitatively described by their BTDF values with high precision, good repeatability and reproducibility. The diffusers’ angle-dependent spectral transmittances in the VIS (from 380 nm to 780 nm in the electromagnetic spectrum) are also measured using a commercially available spectrophotometer. Results are compared to simulation calculated from a simple model and a first-step explanation for the sample spectral dependency is proposed.

New stakeholder Essilor Luxottica

We are happy to announce that Essilor Luxottica has joined the BxDiff Stakeholder group! Essilor Luxottica is a global leader in the design, manufacture and distribution of ophthalmic lenses, frames and sunglasses. The company brings together the complementary expertise of two industry pioneers, one in advanced lens technologies and the other in the craftsmanship of iconic eyewear to address the world’s evolving vision needs and the global demand of a growing eyewear industry.

Workshop & Final Meeting in Hørsholm (DK), Sept. 2022

We are pleased to announce that our closure meeting will be in Hørsholm (DK) at DFM.

BxDiff has been a collective effort between NMIs, academics and industrials with great collaboration. We did significant progress. This last meeting will be the opportunity to make a step back, see what has been achieved in the project, and share this pieces of knowledge.

Outlines of the event :

  • Wednesday 28 Sept – 9 am to 4 pm – Workshop on BRDF, BTDF and BSSRDF models
  • Thursday 29 Sept – 9 am to 5pm – Progress achieved in BxDiff on BRDF, BTDF and BSSRDF
  • Friday 30 Sept – 9 am to 12 am – Construction of a proposal for a next project on metrology of appearance

Venue :
Kogle Allé 5
2970 Hørsholm

 We hope that you can move to Hørsholm (DK) to attend the meeting. Hørsholm is at 30mn by bus from Copenhagen. But if it is not possible, we propose also to attend online.

4th Progress Meeting, Apr 2022 – Madrid

We are pleased to announce that our next progress meeting will be held at IO-CSIC in Madrid (ES). Since our last meeting in June 2021, we have progressed on the development of references for BRDF, BTDF and BSSRDF measurements. This meeting will be occasion to share our results and have scientific debates on those quantities and on their link with appearance of surfaces and visual attributes (colour, gloss and translucency).

Here is how it will be organized :
    – April 26th (9am-5pm) : Workshop on BTDF measurements
    – April 27th (9am-5pm) : Progress in BxDiff on BRDF, BTDF, BSSRDF and models
    – April 28th (9am-12am): Discussion on BxDiff impact + future plans  

Save the date in your agenda. It will be good to have a face to face meeting.
We will build the detailed agenda and do our best to have it ready by beginning of March.

Workshop on BTDF Agenda

4rd Progress Meeting Agenda

Dr. Ferrero awarded DfwG Fellow

During the annual meeting of the German Society of Color Science
and Application (DfwG ) on October 6th 2021, Alejandro Ferrero was awarded DfwG Fellow for his outstanding contributions with respect to goniometric measurement techniques, published in various articles.

The award recognizes Alejandro Ferreros’s valuable contributions to the fields of BRDF, BTDF, BSSRDF, Sparkle and goniometric color measurement, which were generated in many cases in the EMPIR projects xDReflect , BiRD , and BxDiff.

Dr. Ferrero is the first person to receive this novel award, which is dedicated to scientists, lecturers and teachers, engineers and developers who have achieved substantial advancements in color science and related fields of work through their multinational professional work and their outstanding effort.

Dr Alejandro Ferrero in his lab at IO-CSIC (Madrid, ES) presenting “GEFFE” , its “baby”, the goniospectrophotometer that is the most versatile in the world

Workshop on BRDF & speckle – registration

The first workshop of BxDiff will be held at University Jean Monet in St Etienne (France), on Friday 10 December 2021.

It will be a great opportunity to learn about BRDF measurement and speckle – an important issue we are facing now in BRDF measurement when we reduce the bandwidth or when we move to high angular resolution. The apparition of speckle masks the BRDF of the surface. Experts will show the state of the art on this topic.

The agenda : 
    9:00   – Welcome
    9:30   – Gael Obein (LNE-CNAM) | Evolution of BRDF measurement : when the speckle effect arose
    10:00 – Pierre Chavel (Institut Graduate School) | The speckle theory (1) : an introduction
    10:45 – Pierre Chavel & Anthony Cazier (Institut d’Optique Graduate School and University Saint-Etienne) | Educational demo with optical bench
    11:30 – Pierre Chavel | The speckle theory (2) : advanced modelling
    12:30 lunch
    14:30 – Loic Denis (University of Saint-Etienne) | Removing speckle while maintaining resolution : methods in radar imaging.
    15:15 – Thomas Labardens (LNE-CNAM) | Speckle effect in high resolution BRDF measurements
    16:00 – Discussion : is the BRDF of a surface the expectation of the signal measured?
    17:00 – end

Venue information and registration (free but requested) are available on the webpage of the event: here

3rd Progress meeting

Our next progress meeting will be in Visio. It will be on Thursday 10 June 2021, 9-12 am & 2-5 pm (CEST). Please, save the date in your agenda.

This meeting will be open to all our stakeholders, but you need to register in order to get access. Please, register before Tuesday 8 June.

The meeting will consist of presentation of the first results and of the general progress in the project. We are all happy to have this meeting and this share of science with you.

Progress Meeting Agenda

Presentations (please login – only visible for members and stakeholder committee)

2nd Progress Meeting

Due to the pandemic, BxDiff management board has decided to cancel the meeting.

The webmeeting restricted to consortium scheduled on Oct 27th is maintained.

It will be held in Hørsholm (DK) at DFM, 27-28 October 2020
We expect to present full progress at this meeting and we really hope to feature a strong stakeholders participation. Agenda and sessions will be prepared to encourage exchange and share of knowledge. First draft agenda will be shared in September, but for sure, we will talk about measurement and modelling of BRDF, BTDF, BSSRDF, on small, medium and large surfaces.