oral paper Coloured light sequences based on human perception: The case of a lit
sculpture in an urban open space
Jean-Luc CAPRON
Faculté d’architecture, d’ingénierie architecturale, d’urbanisme,
Université catholique de Louvain
Abstract
A research regarding coloured light sequences was conducted on the occasion of the author’s
design of a pyramidal sculpture lit by RGB LED uplights inserted into the base. The goal of this
inquiry was to develop design strategies and methodologies that meet the requirements and
specificities of spatial-temporal sequences by means of coloured lights. In this way, four aspects
such as light, colour, space and time were studied respectively in order to identify priorities for
any further research. First, the RGB light source values were assessed in regard to their visual
sensation. Second, the colour palette was observed, assessed and altered as a whole, in order to
render this colour palette seemingly more continuous. Furthermore, previously determined
relative luminance sensation values were used in order to redesign the RGB coding. On site
experiments hinted towards the avoidance of the feeling of repetition and showed the importance
of observer’s point of view in relation to the spatial organization and segmentation based on the
visual scenes. In conclusion, both, empirical and theoretical research alluded to the importance of
design methodologies of coloured light sequences based on the user’s visual perception in relation
to the temporal and spatial context.
1. Introduction
A research regarding coloured light sequences was conducted on the occasion of the
author’s design of a coloured lit pyramidal sculpture, including the design and integration
of multi-coloured lights as well as their spatial and temporal dynamic aspects.
50
In 2009, on the occasion of the 5th edition of the Festival des Sapins in Liège (BE), the
author designed a sculpture of light and colour to be erected on the city’s main piazza, the Place
Saint-Lambert [Figure 1]. The total height of the sculpture is 6 meters, fixed on a faceted circular
base with a diameter of 3,72 meters. It is composed of 44 “V” shaped moduli made of two welded
semicircular steel plates, painted white matte and tilted. Each module is individually fixed on a
thin cylindrical steel pole. The poles are fixed on top of the base, along a mesh of interlaced
spirals. The moduli, staged on 8 levels, are lit by 20 RGB LED uplights inserted into the base.
[Figure 2].
From the very first sketches, the strategy was to consider the user as the origin and purpose,
affecting both the physical structure of the sculpture, and lighting and colour choices. In order to
design an urban object that would be seen by the pedestrian from different point of views,
numerous proposals were designed using computer simulations.
At the end of the process, the sculpture is perceived as fragmented and homogeneous at the
same time. And the play of coloured lights on the staged modules, set along a maze of spiral
whirls, swaying in the wind, generates a dynamic effect [Figure 3].
AIC 2011 MIDTERM MEETING, ZURICH – INTERACTION OF COLOUR & LIGHT IN THE ARTS AND SCIENCES – PROCEEDINGS
oral paper Figures
1-2-3.The
The“presence”
“presence”
multi-coloured
sculpture
- Staged
modules
set aalong
Figures 1-2-3.
of of
thethe
multi-coloured
lightlight
sculpture
– Staged
modules
set along
maze aofmaze
spiralof
spiral
whirls
Diffuse
reflection
of
the
coloured
lights
on
double
titled
modules
whirls – Diffuse reflection of the coloured lights on double titled modules
FiguresTo
1-2-3.
The “presence”
of the multi-coloured
sculpture
- Stagedby
modules
set along
a maze LED
of
maximize
the light-colour
effectslightmade
possible
Philips
Lighting
spiral whirls - Diffuse reflection of the coloured lights on double titled modules
projectors,
developed
novel
palettes
especially
for LED
the occasion.
To maximizethetheauthor
light-colour
effects
madecolour
possible
by Philips
Lighting
projectors,The
the
To
maximize
the
light-colour
effects
made
possible
by
Philips
Lighting
LED
characteristics
of
each
colour
component
light
sequence
are
weighted
by
perceptual
data.
author developed novel colour palettes especially for the occasion. The characteristics of each
projectors, the author
developed
novel
colour
palettes
for the lighting
occasion.
The
After
colourful
lighting
effects
on
full-sizeespecially
module,
dynamic
scenes
colourvalidation
componentoflight
sequence
are weighted
by aperceptual
data. After
validation of colourful
characteristics
of
each
colour
component
light
sequence
are
weighted
by
perceptual
data.
were
made
using
software
lighting
effects
on aa DMX
full-size
module,interface
dynamic [Figure
lighting 6].
scenes were made using a DMX software
After validation of colourful lighting effects on a full-size module, dynamic lighting scenes
interface [Figure 6].
were made using a DMX software interface [Figure 6].
2. Discussion
An
anthropocentric design of a 3D object, combining light and colour, considers the eye
2.
Discussion
2.
Discussion
the
point ofdesign
a virtual
connects
secondary
surfaces
- thethe
modules
An starting
anthropocentric
of line
a 3Dthat
object,
combining
light emissive
and colour,
considers
eye theAn
anthropocentric
design
of
a
3D
object,
combining
light
and
colour,
considers
the
eye
and
light
sources
- the spotlights.
In terms
of coloured
lighting,
the- the
process
is defined
by
starting
pointpoint
of a virtual
line that
connects
secondary
emissive
surfacessurfaces
modules
- and lightthe
starting
of
a
virtual
line
that
connects
secondary
emissive
the
modules
the physiological characteristics of human vision under mesopic conditions (Purkinje
sources
- the
spotlights.
terms of coloured
lighting,
the process
is defined
by the is
physiological
and light
sources
- theInspotlights.
In terms
coloured
lighting,
defined
by
effect,
cone
sensitivity,
...), how objects
areofilluminated
in space,the
as process
“secondary
emissive
characteristics
of
human
vision
under
mesopic
conditions
(Purkinje
effect,
cone
sensitivity,
...),
the physiological
characteristics
under mesopic
surface”
(colour reflectance,
…) of
andhuman
finallyvision
the characteristics
of conditions
light from (Purkinje
the light
how
objects
are
illuminated
in space,
as “secondary
emissive surface”
(colour
reflectance,emissive
…) and
effect,
cone
sensitivity,
...),
how
objects
are
illuminated
in
space,
as
“secondary
sources (optics, luminance levels, colour temperature, …).
finally
the(colour
characteristics
of light
the light
(optics, luminance
levels,
surface”
reflectance,
…) from
and finally
thesources
characteristics
of light from
thecolour
light
temperature,
…). luminance levels, colour temperature, …).
sources (optics,
Figures 4-5-6. Temporal continuous flow - Spatial organisation and temporal dimension - DMX
transposition of the spatio-temporal dynamic
FiguresThe
4-5-6.
Temporal
continuous
flow
- Spatial
organisation
andstrategies
temporal
dimension
-transposition
DMX
goal
of this
inquiry
to organisation
develop
design
and
methodologies
that
Figures 4-5-6.
Temporal
continuous
flow -was
Spatial
and temporal
dimension
- DMX
of the
transposition of the spatio-temporal dynamic
spatio-temporal
dynamic
meet
the requirements
and specificities of spatial-temporal sequences by means of
The
goal
of
this
inquiry
to develop
strategies
and
that
coloured lights. In this way, fourwas
aspects
such as design
light, colour,
space
andmethodologies
time were studied
meetgoal
the ofrequirements
and tospecificities
offorspatial-temporal
sequences by
of
The
thisorder
inquiry
was
develop
design
strategies
methodologies
thatmeans
meet the
respectively
in
to identify
the
priorities
any furtherand
research.
coloured
lights.
In
this
way,
four
aspectswere
such assessed
as
light, in
colour,
space
timespecific
were
requirements
andRGB
specificities
of
spatial-temporal
sequences
by
means
of and
coloured
lights.studied
In
this
First,
the
light
source
values
order
to define
the
codes
respectively
in
order
to
identify
the
priorities
for
any
further
research.
way, four aspects such as light, colour, space and time were studied respectively in order to
First,
the RGBfor
light
were assessed in order to define the specific codes
identify
the priorities
anysource
furthervalues
research.
AIC – MIDTERM MEETING 2011, ZURICH – INTERACTION OF COLOUR & LIGHT IN THE ARTS AND SCIENCES
2
AIC – MIDTERM MEETING 2011, ZURICH – INTERACTION OF COLOUR & LIGHT IN THE ARTS AND SCIENCES
2
AIC 2011 MIDTERM MEETING, ZURICH – INTERACTION OF COLOUR & LIGHT IN THE ARTS AND SCIENCES – PROCEEDINGS
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oral paper First, the RGB light source values were assessed in order to define the specific codes for the
three primary colours on a 0-255 level scale. Subsequently, these were altered based on the
assessment of the colours on a sample modulus of the final structure, manipulating each of the
RGB components respectively.
Second, the colour palette was observed as a whole. Noticeable discrepancies were noticed
among the subsequent colour gradients. Consequently, the RGB codes were critically assessed
and altered in order to render this colour palette seemingly more continuous. Furthermore,
previously determined relative luminance sensation values were used in combination with the
cube-root chromatic adaptation in order to redesign the RGB coding.
On site experiments hinted towards the avoidance of the feeling of repetition. By
accentuating the perception of primary colours, an illusion of a temporal continuous flow is
induced. The experiments also showed the importance of observer’s point of view in designing
3D coloured light sequences in relation to the spatial organization and segmentation based on the
visual scenes.
To sum-up, the following technical aspects are of importance:
–– Selection of the white coating and its application. The application of a matte paint provides a
finish that diffuses the reflection of the coloured light on the surfaces of the module and
prevents high level of external reflection.
–– Quick tests of the RGB light flux values. Illuminance measurements 1 of the selected light
source gives non-homogeneous results for the RGB sources, with the values for blue equal to
about one third of red and green, and their spatial repartition.
As the characteristics of coloured lights have to be selected and adapted on the basis of human
perception, the following aspects are of importance:
–– Definition of perceived primary colours. Mock-up perception assessments 2 tend to indicate
that on an RGB 0-255 scale, a portion of about one twentieth of one of the other basic hues
should be added; for example 255/0/12, 0/12/255, 0/255/12. Even more satisfactory results
were reached by combining the hues in proportions such as 255/16/128, 128/255/16, 16/128/255
and 16/255/128, 128/16/255, 255/128/16, as complementary.
–– Avoidance of discrepancies in temporal succession of colours. As established during the
aforementioned assessment tests of perceived colours, a perceived continuum of colours
gradient may be improved by steps of sixteen, or so [Figure 4]. This also gives hints for
avoiding a feeling of repetition, by attenuating the perception of colours as primary, thus,
giving the illusion of a more continuous flow.
–– Perceived homogeneity of dimmed coloured light. On-site experimental attempts by means of
the square law curve (IESNA 2000: 27-4) and relative perceived luminance values in regard to
the attractiveness of chromatic light (Kort et al. 2009; Reisinger et al. 2008) suggest promising
results. It clearly helps to create with gentle shifts in tone colours and harmonious perception
of the lit surfaces spatial arrangements.
–– Spatial organisation of the lit modules. Rhythmic lighting sequences 3, with themes such as
“breathing”, “flicker”, “continuum”, … emphasise the third dimension [Figure 5].
1 Measurements made with the students of the course Light in the built environment.
2 Assessments made with Marie-Hélène Huysmans of the former Hic et nunC a.s.b.l.
3 Some sequences were designed by students of the course Colour in the built environment.
52
AIC 2011 MIDTERM MEETING, ZURICH – INTERACTION OF COLOUR & LIGHT IN THE ARTS AND SCIENCES – PROCEEDINGS
oral paper Figure 7.Coloured
Colouredlight
lightsequences
sequences
Figure 7:
3. Conclusion
Conclusion
3.
Both, empirical
empirical and
and theoretical,
theoretical,research
researchallured
alluredtotothe
theimportance
importance
design
methodologies
Both,
ofof
design
methodologies
of
of
coloured
light
sequences
based
on
the
user’s
visual
perception
in
relation
to
the
temporal
coloured light sequences based on the user’s visual perception in relation to the temporal and
and spatial
context.
Considering
the temporal
aspect,
further
improvements
could
be done
spatial
context.
Considering
the temporal
aspect,
further
improvements
could
be done
by
by
integrating
colour
remanence,
both
in
discontinuous
phases
and
in
continuous
gradients.
integrating colour remanence, both in discontinuous phases and in continuous gradients. Regarding
Regarding
the spatial
dimension,
furtherbe conducted
inquiries on
should
conductedof hues
on visual
the
spatial dimension,
further
inquiries should
visual be
attractiveness
under
attractiveness of hues under mesopic conditions with a non homogeneous vision field,
mesopic conditions with a non homogeneous vision field, referring to the Esterman grid, for
referring to the Esterman grid, for instance (Decuypere et al. 2009: 1178). The last area of
instance (Decuypere et al. 2009: 1178). The last area of inquiry is strongly connected to an
inquiry is strongly connected to an ongoing personal research concerning the aspect of
ongoing personal research concerning the aspect of visual scenes in an urban environment.
visual scenes in an urban environment.
The design prize awarded to this sculpture of light and colour affirms that projects using an
The design prize awarded to this sculpture of light and colour affirms that projects
anthropocentric approach are intrinsically positive for the built environment and its components.
using an anthropocentric approach are intrinsically positive for the built environment and
It demonstrates how festive lighting based on rigorous design strategy and combining scientific
its components. It demonstrates how festive lighting based on rigorous design strategy and
data can meet poetic sensibility.
combining scientific data can meet poetic sensibility.
Acknowledgments
Acknowledgements
This
waswas
sponsored
by Yvan
PaquePaque
s.a. (groupe
Eiffage)Eiffage)
and Hicand
et nunC
This research
researchand
andthe
thedesign
design
sponsored
by Yvan
s.a. (groupe
Hic
a.s.b.l.,
with
the
cooperation
of
the
City
of
Liège
and
Wallonie
Design.
et nunC a.s.b.l., with the cooperation of the City of Liège and Wallonie Design.
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Address: Jean-Luc Capron, Faculté d’architecture, d’ingénierie architecturale, d’urbanisme (LOCI),
York: IESNA.
Université catholique de Louvain (UCL), Chaussée de Charleroi 132/134, B 1060 Bruxelles, Belgium
E-mail:
Address:jean-luc.capron@uclouvain.be
Jean-Luc Capron, Faculté d’architecture, d’ingénierie architecturale, d’urbanisme (LOCI),
Université catholique de Louvain (UCL), Chaussée de Charleroi 132/134, B 1060 Bruxelles, Belgium.
E-mail: jean-luc.capron@uclouvain.be
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