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Tables and charts - 3
The New Method To Calibrate Iso/cie General Skies modelled In Artificial Skies Light & Engineering Vol. 29, No. 1

Light & Engineering 29 (1)

Volume 29
Date of publication 02/27/2021
Pages 11–20

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The New Method To Calibrate Iso/cie General Skies modelled In Artificial Skies Light & Engineering Vol. 29, No. 1
Articles authors:
Stanislav Darula, Richard Kittler

Stanislav Darula, Associate Professor, Ph. D. At present, he is senior researcher at Institute of Construction and Architecture, Slovak Academy of Sciences. His professional interest is focus on the research of daylight phenomena, daylight availability, daylight standardization and daylight design in buildings. He is national member of CIE Division 3, CEN TC169/WG 11 and participated in the elaboration of the European standard Daylight of buildings. As a member of the presidium of the Slovak Lighting Society and member of The Association of Slovak Scientific and Technological Societies as well as The Slovak Chamber of Civil Engineers he contributes in the activities in the research and popularization of illuminating engineering. At the Faculty of Civil Engineering of the Slovak University of Technology he is an external lecturer in the course of Building Physics

Richard Kittler graduated in 1953 with honours in Building Science as Diploma Engineer at the Slovak Technical University, Faculty of Construction and Architecture and soon started his postgraduate studies at the Institute of Construction and Architecture of the Slovak Academy of Sciences (ICA SAS) and received in 1957 a Ph.D. and in 1966 D. Sc. degree at the Czech University of Technology in Prague. Since 1953 he is employed as a Scientist, later principal Scientific Officer in ICA SAS at Bratislava in building physics with special regard to daylight research. Best known are his studies of sky luminance patterns in nature and in artificial skies as well as their standardisation for calculation and simulation purposes, now also in the CIE/ISO Standard. His long-term involvement in CIE activities during 1959–2007 was appreciated by the CIE Distinguished Services Wyszecki Award for Fundamentals within the Beijing CIE General Session. In 2002 he was elected to a membership of the European Academy of Sciences. His team has published a seminal book “Daylight Science and Daylighting Technology” Springer, New York, 2012, summarising basic knowledge in this specific subject

Recently sky luminance distributions under fifteen ISO/CIE sky types were standardised in relative terms, i.e. all elementary sky luminance are normalised by the zenith luminance in nature. However, these standard sky luminance patterns can be characterised also in their physical units, see in CIE215:20014 which can be reduced by suitable intensity scales to simulate the very high natural sky luminance in laboratory under artificial sky domes. For the design of the electric illumination system of the artificial sky the appropriate zenith luminance for each sky type has to be derived respecting the indicatrix and gradation functions of each sky type. Thus, the sky patterns simulated in the artificial sky can be calibrated either by luminance measurements or by analysing fish-eye photos taken from the sky centre showing the smoothness and gradual changes of homogeneous sky type luminance patterns. The sky luminance images can be utilised to proceed with the adjustment or dimming of the LED electrical system to the final calibration check containing zenith luminance and exterior illuminance in the second calibration step.
1. Kittler, R. Slnko a svetlo v architektúre (Sun and light in architecture). Bratislava: SVTL, 1956.
2. Darula, S., Kittler, R. A methodology for designing and calibrating an artificial sky to simulate ISO/CIE Sky Types with an artificial sun// Leukos, 2015, V11, pp. 93–105.
3. Darula, S., Kittler, R. The new generation of an artificial sky: simulating various overcast sky conditions// Proc. of the European Lighting Conference Lux Europa 2017. Ljubljana: Lighting Engineering Society of Slovenia, 2017, pp. 401–405.
4. Lambert, J.H. Photometria sive de mensura et gradibus luminis, colorum et umbrae (1760) (Photomery for measuring and grading light, colour and shades). Augsburg: Detlefsen. (German translation by E. Anding: Lamberts Fotometrie. Leipzig: Klett Publ., 1892. English translation by D.L. DiLaura: Photometry, or on the measure and gradation of light, colors and shade. New York: Publ.IES Amer., 2001).
5. Commission Internationale de l´Éclairage,1955, CIE-E3.2 Official recommendation: Natural daylight. Proc. Paris: CIE, II, 3.1.
6. Commission Internationale de l´Éclairage, Technical Report 22 Standardisation of luminance distribution on clear skies, Paris, 1973, CIE Central Bureau.
7. Commission Internationale de l´Éclairage, CIE Standard Spatial distribution of daylight – CIE Standard of General Sky, 2003 CIE Standard S011/E: 2003. Vienna: CIE Central Bureau.
8. International Standard Organisation: ISO Standard 15409:2004 Spatial distribution of daylight – CIE Standard of General Sky. Geneva: ISO, 2004.
9. Kittler, R. and Darula, S. The simultaneous occurrence and relationship of sunlight and skylight under ISO/CIE standard sky types// Lighting Research  Technology, 2015, V47, pp. 565–580.
10. Roy, G., Kittler, R., Darula, S. An implementation of the Method of Aperture Meridians for the ISO/CIE Standard General Sky// Lighting Research  Technology, 2007, V39, #3, pp. 253–264.
11. Kittler, R., Kocifaj, M., Darula, S. Daylight Science and Daylighting Technology. New York: Springer, 2012.
12. Komar, L. Calibration of the artificial sky using fisheye images. Proc. of the VI. IEEE Lighting Conference of the Visegrad Countries LUMEN V4, 2016, pp. 242–245.
13. Baxant, P. Common digital photography and its calibration to luminance measurement. Proc. of the European Lighting Conference Lux Europa 2005, Berlin. Berlin: Deutsche Lichttechnische Gesellschaft e.V., 2005, pp. 318–321.
14. Kobav, M., B. Uporaba digitalnega fotoaparata s širokokotnim objektivom v funciji merilnika porazdeletve scetlosti neba (Using a digital camera with a wide-angle lens in the function of the sky luminance distribution meter). Proc. Conference Razsvetljava 2006, Bled. Maribor: Lighting Engineering Society of Slovenia, pp. 167–178.
15. Škoda, J. (2014). Kalibrační protokol k přístroji Nikon D80 s fisheye objektivem, č. 11/2004-SAV (Protocol of the calibration Nikon D80 with fisheye lens No. 11/2004-SAV), Laboratoř světelné techniky, Brno: VUT, 2004.
16. Tregenza, P. Subdivision pf the sky hemisphere for luminance measurements. Lighting// Research  Technology, 1987, #1, pp. 13–14.
17. Darula, S., Kittler, R. New trends in daylight theory based on the new ISO/CIE Sky Standard. 1. Zenith luminance on the overcast skies// Building Research Journal, 2004, V52, #3, pp. 181–197.


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