Paula Menino Homem [Ed.] 2016 LIGHTS ON… CULTURAL HERITAGE AND MUSEUMS ! TITLE Lights on… Cultural Heritage and Museums! EDITOR Paula Menino Homem LabCR_Laboratory for Conservation and Restoration | EDITION FLUP_Faculty of Arts and Humanities, University of Porto PLACE Porto DATE 2016 E-ISBN 978-989-8648-98-3 COVER _L OGO @ Ricardo Medina Design The content of the texts and image rights are the responsibility of the authors. CONTENTS 1 INTRODUCTORY NOTULA SCIENCE OF VISION. THE PERCEPTION OF COLOUR AS A FUNCTION OF ILLUMINATION 4 PHYSICAL PRINCIPLES ON THE ILLUMINATION OF DISPLAYED MUSEUM OBJECTS Luís Miguel Bernardo 18 PHYSICS AND BIOLOGY OF COLOUR AND VISION Carlos Fiolhais 34 COLOR ADD. COLOR IDENTIFICATION SYSTEM FOR COLORBLIND PEOPLE Miguel Neiva 44 OPHTHALMIC INSTRUMENTS IN A MUSEUM OF SCIENCE Marisa Monteiro, M. João Carvalhal BUILT ENVIRONMENT. LIGHTING SYSTEMS. REQUIREMENTS, SOLUTIONS AND TRADITIONS 62 LIGHT AND COLOUR IN THE BUILT ENVIRONMENT João Pernão 80 ELECTRO -CERAMICS CANDAL , V.N. GAIA ; THE PRODUCTION OF ELECTRICAL APPARATUS Graça Silva LIGHTS AND COMMUNICATION AND MEDIATION 99 COMMUNICATE Suzana Faro 110 USING 3D MODELS IN MUSEUMS : THE POTENTIAL CASE OF "C ASTRO DE ROMARIZ 3D" PROJECT Pedro da Silva 123 MICHELANGELO'S DAVID : AN AUGMENTED REALITY APPLICATION ON REAL SCALE , USING THE TECHNIQUE OF VIDEO MAPPING Donato Maniello v HERITAGE AND LIGHTS. INTERACTIONS FOR CHARACTERIZATION AND PERCEPTION 140 PORTABLE XRF: A (VERY ) BRIEF INTRODUCTION Lee DraKe HERITAGE AND LIGHTS. INTERACTIONS FOR DOCUMENTATION AND PERCEPTION 163 TOWARDS A COMBINED USE OF IR, UV AND 3D-IMAGING FOR THE STUDY OF SMALL INSCRIBED AND ILLUMINATED ARTEFACTS Athena Van der Perre, HendriK Hameeuw, Vanessa Boschloos, Luc Delvaux, Marc Proesmans, Bruno Vandermeulen, Luc Van Gool, Lieve Watteeuw 193 DIGITIZING 3D HISTORICAL SCIENTIFIC INSTRUMENTS WITH LASER AND PHOTOGRAPHIC TECHNOLOGIES Ricardo Marroquim, Daniel Coutinho, Marcus Granato INTEGRATED RISK MANAGEMENT. PREVENTIVE CONSERVATION 212 RISK MANAGEMENT : FASHION AND UNCERTAINTY Jonathan Ashley-Smith 231 LIGHTENING THE LEVELS - CONTROLLING DAYLIGHT IN CHALLENGING SPACES Anna StarKey 245 MANAGING NATURAL LIGHT IN HISTORIC PROPERTIES David ThicKett vi INTRODUCTORY NOTULA Paula Menino Homem 1 Facing serious times of change, museums and other cultural institutions, discuss and reflect, in a deeply and interdisciplinary way, about their role in resilience, sustainability and quality of life of the XXI century society. The XXI century is seen as the Century of Light, as light and light-based technologies are recognized as major economic drivers with the potential to revolutionize it. In that sense, UNESCO proclaimed 2015 the International Year of Light (IYL2015), also noting “that 2015 coincides with the anniversaries of a series of important milestones in the history of the science of light, including the worKs on optics by Ibn Al-Haytham in 1015, the notion of light as a wave proposed by Fresnel in 1815, the electromagnetic theory of light propagation proposed by Maxwell in 1865, Einstein’s theory of the photoelectric effect in 1905 and of the embedding of light in cosmology through general relativity in 1915, the discovery of the cosmic microwave bacKground by Penzias and Wilson and Kao’s achievements concerning the transmission of light in fibres for optical communication, both in 1965” (United Nations, A/RES/68/221, 2014). Such revolution happens and has significant impact on cultural heritage and museums. Aware of the process, we joined the international initiatives on the IYL2015 and organized the International Congress Lights On… Cultural Heritage and Museums! 1 DCTP_Department of Heritage Studies, CITCEM_ Transdisciplinary Research Centre «Culture, Space and Memory», FLUP_Faculty of Arts and Humanities University of Porto, [email protected] 1 (https://lightsonchm.wordpress.com/ ), held in Porto, Portugal, on July 20 th , 21 st and 22 nd 2015. The congress adopted the concept of light in its broader meaning, that is, not only the form of energy associated with the visible portion of the electromagnetic spectrum, but also all other invisible radiation such as X-rays, ultraviolet, infrared, among many. It aimed to raise and enhance awareness for its potential and crucial role in cultural heritage and in inclusive museums. Assuming a multi and interdisciplinary character, it strengthened the cooperation bonds between professional, scientific and educational communities and generations. It provided a platform for sharing experiences and Knowledge about important scientific and technological advances in the field, featuring Thematic Sessions, with Invited SpeaKers and Oral Presentations, Poster Session and WorKshops. The official language was English and the focus was on the following topics: 1. Science of vision. The perception of colour as a function of illumination 2. Lighting systems in museums / historical buildings / monuments. Requirements and scientific and technological developments 3. Built environment. Solutions. Energy resources and sustainability 4. Study and safeguard of heritage associated with the production of energy and electric lighting 5. Scientific examination of heritage and analytical applications using different radiation. Research on i. Materials, technologies, functions and producers 2 ii. Alteration processes and diagnosis 6. Technologies of communication and mediation 7. Curative conservation and restoration 8. Integrated risK management. Preventive conservation We are pleased to share with you a selection of the contributions, hoping the reading may be fluid and pleasant and the thoughts and information useful. 3 SCIENCE OF VISION. THE PERCEPTION OF COLOUR AS A FUNCTION OF ILLUMINATION Bernardo, L.M. (2016), Physical principles on the illumination of displayed museum objects. In: Homem, P.M. (ed.) Lights On… Cultural Heritage and Museums!. Porto: LabCR | FLUP, pp.4- 17 PHYSICAL PRINCIPLES ON THE ILLUMINATION OF DISPLAYED MUSEUM OBJECTS Luís Miguel Bernardo 1 ABSTRACT The illumination of displayed museum objects must fulfil basic requirements such as the established conservation rules, aesthetic values and the visitors’ viewing expectations. Therefore, choosing the right intensity and spectral colours of those objects’ illumination is a very demanding tasK to curators, light designers and engineers. For a correct decision, the basic principles of white light composition, the light interaction with the materials, the measurement of the intensity and colours, and the human visual perception must necessarily be considered. The spectral analysis and synthesis of white light are particularly relevant to understand the objects’ physical colours. The use of a particular spectral composition may be constrained by the object conservation restrictions and the public aesthetic and visual expectations and therefore alternative choices must be considered to overcome those possible incompatibilities. Radiometric and colorimetric measurements must be made to characterize the illumination conditions and establish the best set-up. The physical observation conditions must be evaluated through the Knowledge of the reflection, transmittance, absorption and scattering phenomena, affecting colours and intensities. Finally, the physiological effects of a particular illumination on the human vision have to be evaluated through the principles of photometry and human vision physiology. KEYWORDS Lighting; Illumination; Colour; Radiom etry; Photometry 1 Department of Physics and Astronomy, Faculty of Sciences, University of Porto, Portugal, [email protected] 4 Bernardo, L.M. (2016), Physical principles on the illumination of displayed museum objects. In: Homem, P.M. (ed.) Lights On… Cultural Heritage and Museums!. Porto: LabCR | FLUP, pp.4- 17 1. Introduction For the illumination of displayed museum objects, we must taKe in consideration the requirements and constrains associated to the object and the observer. Lighting with a suitable light spectral composition and correct levels of illuminance must satisfy the object preservation limits and fulfil objective and subjective viewing conditions, such as colour rendering (fidelity) and the observer’s comfort. To preserve the object integrity, the illumination must have a spectral composition not to induce photochemical reactions, photo- degradation, colour fading, degradation, or heating which may cause the expansion, cracKing and detachment of the object materials. The concept of colour temperature (CT) is used to spectrally characterize incandescent lamps, since their spectra throughout the visible region can be very closely approximate to that of a blacKbody. BlacKbody or PlancKian locus is the line path, in the CIE chromaticity diagram, that represents the colour of a blacKbody at different temperatures. Therefore, the colour temperature of an incandescent lamp can be read on that line (FIG . 1). For other lamps producing white light that don’t have chromaticity coordinates that fall exactly on the PlancKian locus but lie near it, the correlated colour temperature (CCT) must be used instead to characterize their temperatures. The CCT of a light source, expressed in Kelvins (K), is therefore defined as the temperature of a blacKbody, which is closest to the chromaticity of that source. It is an essential measuring parameter in the general lighting to specify the perceived colour of an artificial non- incandescent lamp. 5 Bernardo, L.M. (2016), Physical principles on the illumination of displayed museum objects. In: Homem, P.M. (ed.)