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TitleCIE 2018 Conference on Smart Lighting
LanguageEnglish
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Total Pages201
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CIE 2018 Conference on Smart Lighting

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Contents



Session PA1-1 Integrative lighting and health (1) ................................................................................. 10

Session PA1-2 Adaptive, intelligent and dynamic lighting in interior environment ............................. 16

Session PA1-3 Colour quality ................................................................................................................. 25

Session PA2-1 Displays and imaging devices with lighting applications ............................................... 30

Session PA2-2 Adaptive, intelligent and dynamic lighting in exterior environment ............................. 38

Session PA2-3 Colour and vision (1) ...................................................................................................... 48

Session PA3-1 Integrative lighting and health (2) ................................................................................. 58

Session PA3-2 Solid-State Lighting (SSL) technologies .......................................................................... 66

Session PA3-3 Colour and vision (2) ...................................................................................................... 73

Session SE1 Seminar LOC invited papers (1) ......................................................................................... 82

Session SE2 Seminar LOC invited papers (2) ......................................................................................... 90

Session SE3 Seminar LOC invited papers (3) ......................................................................................... 95

Session PS1 Presented Posters (1) ........................................................................................................ 97

Session PS1 Presented Posters (2) ...................................................................................................... 111

Session PS1 Presented Posters (3) ...................................................................................................... 124

Poster Session ..................................................................................................................................... 138







Note: For Sessions SE1, SE2, SE3 (invited presentations of the Local Organizing
Committee) abstracts are only partly available.

CIE 2018 Conference on Smart Lighting - Abstracts

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PP02

Depreciation of Room Surfaces Reflectance and their influence on Maintenance Factor
of Lighting Systems

Gasparovsky, D.1, Dubnicka, R. 1
1 Slovak University of Technology in Bratislava, SLOVAKIA

[email protected]

Abstract

1. Motivation, specific objective

Maintenance Factor (MF) is the key parameter used in any design and measurement of lighting systems.
Its role is to adjust the calculated or measured value of target lighting parameter (illuminance or
luminance) with respect to the end of maintenance cycles (i.e. time when the maintenance is to be
carried out) so that anytime the lighting level satisfies the given requirement. Once the lighting system
is put to operation, ageing and environmental influences are responsible for depreciation and continuous
decrease of illuminance or luminance or in systems with CLO control continuous increase of power
consumption. Depending on lamp type or luminaire type some of the changes can be eliminated by
maintenance (e.g. relamping, cleaning of optical parts) and some must be related to the end of life (non-
recoverable losses due to ageing of optical parts, luminous flux depreciation and mortality of non-
replaceable LEDs).

Maintenance Factor for interior lighting systems is dealt in the Publication CIE 97:2005 and for exterior
lighting systems in the Publication CIE 154:2003. Methods for determination of the maintenance factor
are, however, decades older and neither reflect the current level of technology nor the current quality of
environment. Update of the both technical reports is in terms of reference of the new joint technical
committee (obviously JTC 12).

Full structure of the maintenance factor comprise luminous flux maintenance factor (LLMF), lamp
survival factor (LSF), luminaire maintenance factor (LMF) and room surface maintenance factor (RSMF).
For exterior applications, LSF and RSMF are not used, the latter due to inexistence of walls and ceiling
outdoors. However, novel approaches tend to propose establishment of this component back to MF for
tunnel lighting, underpasses and similar applications.

This paper deals specifically with the RSMF component of the maintenance factor. Loss of reflectance
of the walls, ceiling and floor undoubtedly has influence on target lighting parameters and extent of this
influence depends on many factors like room shape factor, initial (or nominal) reflectances, luminous
intensity distribution of luminaires and cleaningness of the environment. As the problem is very complex,
to determine this component for a given room or space with careful consideration of all the factors is
almost impossible. Currently available methodology is too simplified and inaccurate. It is also not
possible to consider different luminaire types installed in the same room or space.

Proposal of a new method is based on exclusion of RSMF from the maintenance factor, or in other
words, separation of the maintenance factor to the part associated with individual luminaires and the
part associated with surfaces. New surface factor will be directly incorporated in the value of reflectance.
Accuracy of this approach is in sole estimation of reflectance decrease. How luminous flux from
luminaires hits these surfaces and how their reflection affects lighting parameters on the target area, is
matter of ordinary lighting calculations. Thus, tables for different room shape factors and luminaire types
(expressed through the direct flux fraction) can be avoided.

Aim of this paper is to present the new proposal for determination of the RSMF component as a self-
standing surface factor associated directly with surfaces, taking into account environmental conditions
and depreciation of reflectance in time under these conditions.

2. Methods

Depreciation of the reflectance of walls is being monitored in different applications (usage pattern,
environment) with focus on (but not only) office rooms and class rooms. Up to now, 2-year data have
been collected. Samples of 600 x 600 mm are placed on walls and taken for measurement of reflectance
after stated periods of time. The known shape of depreciation curve is typical for a knee short after
installation and with long time of steady-state value of reflectance. To save time and to cycle

CIE 2018 Conference on Smart Lighting - Abstracts

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measurements more frequently it is practical to capture the knee bend and to terminate the depreciation
right after steady-state is reached. Reflectance is measured in laboratory condition by the
luminance/illuminance method assuming that the surface is ideally diffuse. Additional measurements
are carried out for real surfaces in rooms with known time of the last paint renovation. Aim of the
measurements is to study the nature of depreciation of common paints and to derive a table of values
for the surface factor.

Influence of the depreciation of room surfaces reflectance on target lighting parameters is studied on
model calculations for different shape factors, luminous intensity curves, arrangement of luminaires and
illuminance levels. Model calculations are carried out with the Dialux calculation software.

3. Results

Proposal of a new method for determination of the maintenance factor split to luminaire associated and
surface associated components will be explained in details. The paper will focus on the surface factor
component.

The paper will publish results of the measurement of surface samples in different applications.
Depreciation curves will be confronted with the currently available figures in CIE 97. New values for
direct adjustment of reflectances instead of calculated or measured lighting parameters will be proposed.

Results of model calculations will be analysed. Based on analyses, benefits of the novel approach will
be confirmed.

4. Conclusions

Results presented in the paper will show a justification for the new approach of separation of the surface
factor from the maintenance factor, leaving it associated with luminaires only. Depreciation of the
reflectance of room surfaces still need to be investigated with respect to the quality of environment which
itself is the subject of further research. It was found out, for example, that depreciation of reflectance is
uneven and it is related with circulation of air in rooms which carries dust and other pollutants – therefore
contamination of wall centres will differ from corners. Good selection of real installations and/or artificial
deposition of dust and dirt on samples will be essential. Further measurements should continue to
provide wider set of data. More precise monitoring of air quality and possibly monitoring of air flow should
also take place.



CIE 2018 Conference on Smart Lighting - Abstracts

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Regarding the influence of gender on visual perception, the results indicate that gender had significant
impacts on visual perception in different surface material of commodity. This suggests that there was
strong gender difference in assessing visual perception for surface materials of commodity, especially
in freshness and attractiveness. In addition, for the surface materials of commodity condition with a
metal and plastic, the male observers felt more satisfied than the female observers.

4. Conclusions

In our study 32 younger and elderly respondents participated with the purpose to reveal the impact of
the white LED lights on various surface materials of commodity in commercial refrigerator. The
experimental results show that for the effect of surface material of commodity, no significant difference
was found in visual perception. For the effect of age, no significant difference was found in visual
perception. However, a strong gender effect in visual perception (freshness and attractiveness) was
found for surface material of commodity under the metal and plastic.

5. Acknowledgement

This study was supported by the project “Research and Development of LED Lighting and Lighting
System Efficiency Technology” of the Bureau of Energy–Ministry of Economic Affairs in Taiwan.



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PO38

A REAL-TIME SYSTEM TO ENHANCE LEGIBILITY AND AWARENESS OF TEXT
INFORMATION FOR AN OPTICAL SEE-THROUGH HMD

Yu-Jung Lin and Pei-Li Sun
Graduate Institute of Colour and Illumination Technology,
National Taiwan University of Science and Technology

No.43, Sec. 4, Keelung Rd., Da’an Dist., Taipei 106, CHINESE TAIPEI

[email protected]

Abstract

1. Motivation, specific objective

Wearable devices are more and more popular in recent years and optical see-through HMD (denoted
as OST-HMD) is likely to be one of the major wearable device for future AR applications. However, in
an outdoor environment, bright and complex scene would greatly reduce the legibility of text displayed
on the OST-HMD. Orlosky’s study shows that users are more aware when using an OST-HMD
compared to a smartphone device. We exam text colour and rendering method for the type of
applications. A series of visual experiments were conducted to summarize the rules of text placement
and text rendering for the applications. The aim is to develop a rendering model to automatically

enhance the legibility of text displayed on the OST-HMD in an outdoor environment.

2. Methods

In this study, 3 different masks, text only, transparent text box, and text plus box, were tested. 4 real
scenes were tested. Experiment ask 10 participants to answer the legibility and awareness of text
information in 9 locations individually by a 7 point Likert scale. Test 1 applied only green colour to the

3 masks as the colour is bright and has higher awareness to most of colours. Test 2 applied yellow text

with a magenta box to enhance both awareness and legibility. Test 3 chose colour with maximum colour
difference to the background area. We also set 3 different weights to lightness, chroma and hue
differences in the Test 3. The colour and complexity of the scene behind the HMD was estimated by a
video camera mounted on the HMD. The estimation is limited by the dynamic range of the video camera.

3. Results

Overall results show the Text 2 Mark 3 model is the best one when the background information is
unknown. The results of legibility are highly correlated to awareness. To choose a text rendering model
for more critical viewing conditions, we evaluate regions with top 25% mean lightness (L*) or top 25%
standard deviation of lightness (L*) by the video camera. The result shows the (1:2:1) weighted colour-
difference model in Test 3 won the highest scores. However, the computation cost is higher. The cost-
effective Text 2 Mark 3 model also is recommended.

4. Conclusions

The results show that the brightness of background image plays very most important role. To make the
text visible, its’s better to place a text in a dark and uniform area. A transparent text box is more visible
than text only mode. The text colour should be bright and the colour is complemental to the background.
We have developed a real-time system to verify that the proposed text rendering model can be used to
choose an optimal place in the viewing zone of the OST-HMD to enhance the legibility and awareness
of the text.

CIE 2018 Conference on Smart Lighting - Abstracts

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