Exploration
into formal aesthetics
in design: (material) texture
Dr Hengfeng Zuo, PhD, MSc, MA
Research Fellow in Product Design
Faculty of Technology, Southampton Solent University, UK
Email: heng-feng.zuo@solent.ac.uk
Mark
Jones, BA, MCSD
Senior
Lecturer in Product Design
Faculty of Technology, Southampton Solent University, UK
Email: mark.jones@solent.ac.uk
Abstract
The connotation of aesthetics can include a
number of aspects such as technological aesthetics, functional aesthetics,
formal aesthetics, psychological and cultural aesthetics and so on. Formal
aesthetics concerning shape, colour, materials, texture, space etc (and of
course their combination) is the fundamental target that designers should
exclusively achieve, which radically/directly determines the ‘styling’ of any
3D product and environment. Our research focuses on the systematic
investigation into the material texture. Compared to colour, texture is a less
identified property. Although an increasingly wide range of materials with
abundant textures and surface effects are currently available in market, little
has been understood about how human (both designers and users) respond and perceive
them, either physiologically via their senses such as vision, touch etc or
psychologically and culturally via their mind. This part of knowledge will
enable design practitioners to take into consideration the rational thinking of
texture creation and application as assistance to their innovative practice.
Based on experimental research with speculative research, and combining with
examples, this paper addresses a series of issues about texture, including the
concepts of and clarification between texture and perceived texture (texture
perception); the dimensions of verbal description of texture; psychophysical
relationship between subjective feelings of texture and physical parameters of
materials; also addressed is the resources and inspirations from where texture
can be generated.
Key words: texture, aesthetics, materials, sensation and perception, design
1. Introduction
Aesthetics, usually
defined as the branch of philosophy that deals with the nature and expression
of beauty [1], has been recognised since antiquity and has continually evolved
over time. The word beauty is commonly applied to things that are pleasing to
the senses, imagination and/or understanding. It is often what an artist or a
designer makes great efforts to achieve in their works, either for personal or
mass interest and pleasure. Aesthetics can have different meanings from
different perspectives of approach and study. For example, a designed and
manufactured artefact can be judged as beautiful or pleasing because of its
unique functions (functional aesthetics), the application of advanced
technology (technological aesthetics), its fascinating form characteristics
such as attractive shape, colour, texture etc (formal aesthetics), or its
representation of life experience and social identity or a symbol of cultural
reflection (psychological and cultural aesthetics). These aspects are twisted
together in their contribution to the whole perception of product aesthetics.
Figure 1 shows a kettle that uses smart material to give a particular function
of indicating the water temperature. This is realised by the colour changes of
the thermo-sensitive material at different temperatures. At the boiling point,
the material turns into a red colour. The product gives you a sort of fun in
addition to fulfil its basic function of boiling water. It is a trend for
consumer products to have their unique personalities and evoke emotional
feelings such as pleasure within the context of today’s consumption culture. We
can see from this example that how interaction between technology (smart
technology), function (temperature indication), form (materials, colour), and
culture (consumption culture, emotions and pleasure) contributes to product
aesthetics.
However, it is widely
agreed that, in the first instance, aesthetic experience comes from the senses,
or sensations [2], [3]. When we say that a colour is beautiful, a smell is
nice, or a texture is fascinating, it is because the colour, or the smell, or
the texture gives you the sensory pleasure to your sensory organs such as eyes,
nose, skins/muscles, etc. In addition, they may evoke some positive
associations with anything in your memory, life experience, social events etc.
This is why formal aesthetics, which mainly concerns shape, colour, materials,
texture, space and proportion etc (and of course their combination), is a
fundamental goal that designers should try to achieve. These formal elements
radically determine the ‘styling’ of any 3D products and significantly
influences users’ perception of the product’s beauty and value.
Research evidence shows
that the sensory and perceptual aspects of colour and sound have been widely
explored. This is not the case with texture, particularly tactual texture, or
smell and taste. Compared with the properties of colour, sound etc, texture
seems to be a property that is more ambiguous and difficult to identify. We can
use three dimensions of hue, lightness and saturation or the RGB parameters to
describe and accurately specify and identify a particular colour. A series of
standard colour systems such as Munsell, Pantone, NCS etc are available for
colour specification in the market place. However, we tend to know much less
about how to specify a texture, and even less as to how to identify a unique
texture. Although due to development in computer science, it is possible to
design, manipulate, and retrieve a texture, it is dominated in the case of two
dimensional images or virtual images. Systematic understanding about texture in
a wider range of areas, beyond merely visual images, and particularly including
the textures of physical materials, has not been extensively explored. This
paper has a probe into the material texture perception from the practical
perspective of design. In this context, we will skip the black box that deals
with the mechanism about how texture information is processed in the brain, but
focus on a more peripheral aspect. This includes a texture’s definition and
classification; how people subjectively describe a texture; how subjective
responses to texture can be related with objective texture parameters; and what
are the sources for a texture to be generated in the design practice.
2. Concept
of texture
The word ‘texture’ was
originally a textile term, a quality of fabrics appraised and appreciated
through the sense of touch [4] (Figure 2).
The concept was then expanded to a wider range from a philosophical and
cognitive angle of view. Cognitive scientists have recognised texture as a visual cue [5] that plays a significant role in a
variety of cognitive tasks. A common use is in describing and differentiating
between different kinds of objects, either two-dimensional for example an
image, or three-dimensional for example wallpaper, furniture, carpets, sand,
and grass etc. A working definition of texture in this context is the surface
markings on an object or the 2-D appearance of a surface [5]. However, this definition is one-sided
because texture is not merely a visual cue, but could be served as the cue of
other senses. For example, texture should go beyond merely surface markings,
and should concern other characteristics such as the moisture retention level,
thermal conduction, temperature, softness or hardness etc. Texture, in a wider
range of understanding, can also be used to depict the structure of other
things such as a poem, a piece of music [4].
Due to the standpoint
of approaching the research from 3D design perspective, we would like to narrow
down the meaning of texture within the context of physical materials. Within
this context, texture can be understood from two aspects or two scales. On one
hand, it is appreciated for a material’s visual appearance and tactual feel at
the macro scale (Figure 3). On the other hand, texture was transplanted to a
more specific term in the study of materials science and engineering. In this
field of study, texture means a particular orientation distribution in
microstructure. When a piece of metal is deformed by some directional process
such as wire-drawing, extrusion, or rolling, the constituent crystal grains
acquire a preferred orientation. This orientation is called texture [6] (Figure
4). The orientation can result in changes of material properties. Nevertheless,
because of its micro-scale magnitude (the crystallitic grain size is usually
from 1mm to 100mm or even smaller from 1nm to 100nm (nano-materials), texture under
this context is difficult for a human to perceive directly by sensation. This
texture can only be tested and analysed by means of specialist equipment such
as an X-ray diffraction device or microscopy etc. However, these two aspects of
material texture can be, although not always, related. For example, a shiny,
transparent texture of diamond is related with its specific crystal structure
where carbon atoms are arranged in a face-centred cubic lattice and with a
regular tetrahedral structure. The various textures shown on the section
surface of different types of wood are determined by their growing mechanism.
At the rest part of the paper, we will focus on the exploration of material
texture from the sensory and macro aspect.
It is necessary to discriminate between two concepts. One is texture; the other is perceived texture or texture perception. The former is
objective, whilst the latter is subjective. We propose to define ‘texture’ as ‘the geometrical configuration and
physical-chemical attributes of surface or bulk of materials/objects’.
Correspondingly, we propose a definition of perceived texture as ‘a synthesis of physiological and
psychological response and impression to the geometrical configuration and
physical-chemical attributes of the surface or the bulk of materials/objects’. In this definition, the ‘synthesis’
means it is not simply ‘A (geometrical configuration) plus B (physical-chemical
attributes)’ but ‘A fusing with B’, therefore the subjective responses to A and
B would interact. Although under certain conditions (e.g. by vision), the
response to geometrical characteristics may be dominant over physical-chemical
attributes of texture, or the inverse, under other conditions (e.g., by
blindfold touch). What’s more, the
subjective response will possibly go beyond these two aspects as can be found
in our experimental research. The
understanding of the correlation between the objective texture attributes
(usually represented by physical parameters) and the subjective texture
perception will provide the framework for creating suitable, aesthetic material
textures.
3. Classification
of texture
Texture can be
categorised in different ways from different viewpoints. Following are some of
the examples of texture categories:
§
Natural texture and artificial texture (according to the formation of
texture);
§
Regular texture and random texture (according to the pattern of
texture);
§
Visual texture and tactual texture (according to the perceptual
modality);
§
Virtual texture and real texture (according to the
representation of texture).
However, these
classifications of texture can also be intersected. For example, a wood texture
can be attributed as a natural texture. At the same time, it can be a random
texture due to its freely scattered line-patterns. With a particular surface
treatment, for instance, by a layer of other material coating (e.g. varnish,
lacquer) on wood surface, it can also have the attributes of artificial texture.
If presented as an image, it is a visual texture. If it is simulated by computer software,
then it is virtual texture. When it is presented as the surface of a piece of
furniture, it is visual plus tactual texture, and also a real texture.
4. Subjective
description of texture
In the design field, knowing how people describe the
sensory properties contributing to formal aesthetics, including colour,
texture, sound smell, etc, will ensure a consistent communication language
between designers and consumers and enable designers to establish criteria for
a product if it is to achieve good sensory adaptation and aesthetic
expectation. Researchers have tried to find the dimensions for texture
perception in the cases of different material categories such as building materials
[7], wood [8], paper [9] and leather [10], [11] etc. However, all the character dimensions (words
or word pairs) of texture description are different between researchers and
show a lack of a systematic classification.
From our experimental research, a {Dimension-lexicon} system
[12] has been proposed to summarise the material
texture description. It is
generally accepted that the subjective description of
material texture can be summarised into four dimensions: geometrical dimension,
physical-chemical dimension, emotional dimension and associative dimension.
Each dimension has a number of descriptive words that are most frequently used
by subjects. These words are put into pairs that have bipolar meanings such as hard
– soft, shining – non-shining etc, and are named as texture
lexicons. However, the texture lexicons will slightly change in quantity, and frequency of being used when the controlled condition is changed. These conditions
include sensory modality, material categories, subject background etc.
Geometrical dimension This dimension
describes the subjective response to the geometrical configuration of a
material surface. The texture lexicons within geometrical dimension include the
description of a material surface in two aspects: One is the global, macro
impression of the surface configuration, i.e. the surface pattern, such
description as plain – bumpy, regular – irregular, repetitive – non-repetitive, line-scattered – dot-scattered, simple – complex etc. The other is the local,
micro feeling of the surface configuration, i.e. the surface roughness,
described as smooth – rough, fine – coarse etc. Therefore, a plain surface can be rough, whilst a bumpy surface can be smooth. Figure 5 shows an Aluminium
texture that is globally bumpy but locally smooth. However, the discrimination
between the surface pattern (macro) and surface roughness (micro) is sometimes
ambiguous.
Physico-chemical
dimension This dimension describes the subjective response to
the physical and/or chemical attributes of a material surface. It includes the
dynamic characters that need energy exchange (such as mechanical, thermal,
optical, etc) with environment and is time-related. High-frequency lexicons
used in this dimension include such as: warm – cold, hard – soft,
moist – dry, shiny – non-shiny, sticky – non-sticky, etc.
Emotional dimension This dimension
describes the affective, hedonic, valuable feelings that are evoked by touching
the material surface. High-frequency lexicons in this dimension include such as: comfortable – uncomfortable, lively/cheerful – dull, elegant – ugly, modern – traditional, etc. Subjects seem to be more sensitive
to the emotional feelings under the visual touch conditions. However, when
blindfolded, subjects are still equally sensitive to the feeling of comfort comfortable – uncomfortable when touching the
material surface [12].
Associative dimension This dimension
describes the subjective association from the material, i.e. to what existing
things in the perceiver’s life experience can the texture be compared. This
description is beyond the description of geometrical and physico-chemical
characteristics, and is much more individually dependent. Therefore the
lexicons in this dimension are random, and have low frequency, but they are rich
in description. Figure 6 shows some examples of such associative descriptions.
Understanding of this association can be helpful in texture selection in order
to integrate positive user experience to the context where the texture is
applied.
e. buddhist d. silky c. oily b. honeycomb-like a. feather-like
Figure 6 associative description of material texture
5. Psychophysical
relationship in texture perception
There
are often certain physical parameters of materials that underlie or correspond
to subjective descriptions of texture. It is the parameters that determine the
objective side of texture. Understanding the relationships between the
objective parameters and subjective responses will help to further identify the
technical aspects of texture selection, to pinpoint particular technical
processes for materials and surfaces with suitable parameters, which correspond
to the maximising mixture of positive user feelings. This will have great
significance in the new product development process.
This type
of knowledge can actually be traced back into Psychophysics, the oldest stream
of psychology that particularly explores the relationship between physical
world and mental world. An example can be found in the study of sound, the physical
intensity of sound is different with psychological intensity of sound. The
latter is then called loudness. Loudness is a psychological experience that
correlates with, but not identical to, the physical measurement of sound
intensity. For example, an 80db sound does not sound twice as loud as a 40db
sound, and the increase from 40db to 50db will not be judged as the same
loudness increase as that from 70 to 80db [13]. Similar relationship needs to
be explored in the case of texture.
We have
conducted experimental research to find a relationship between subjective
feeling of materials with physical parameters such as roughness and hardness
[14]. It needs to be pointed out that the traditional psychophysical research
focuses on two variables that address the same stimulus (say, roughness, or
warmth, or softness etc), of which one is physical, and the other is psychological. In addition to this ‘one to one’
relationship, a ‘one to more’ or ‘more to one’ relationship is also worth
exploring as long as this kind of relationship does exist. For example,
people’s psychological feeling of a surface’s moisture could be related to a
number of physical factors, such as different materials with different surface
energy[1],
or the same type of materials with different surface roughness, or the same
type of materials but with different softness [11]. On the other hand, one
physical parameter, e.g. the physical roughness, can correspond to a number of
psychological feelings, e.g. subjective roughness, stickiness, warmth. The
relationship between physical roughness and psychological roughness tends to conform to a
power law [7] [14]. We are currently also investigating the quantitative
relationship between psychological responses to material texture and the
material surface gloss.
6. Resources
& inspiration of texture generation
In general, when a
designer makes a decision to use a particular texture, either a material
texture in a 3D context or an image texture in a 2D context[2],
the decision will usually be based on three aspects: knowledge, inspiration,
and experience. Knowledge is rational, and inspiration is intuitive, whilst
experience offers reference of synthetic information from practice. From the perspective of generating a visual
effect of texture, there is little difference between material texture (3D) and
image texture (2D). However, from the perspective of realising the visual
effect on a physical surface, the decision making of texture selection will be
more complex as there will exist certain constraints from the technical side
(e.g. manufacturing processes). At the same time, not just visual attributes
but also tactual feelings or other sensory attributes (sound, smell etc) need
to be considered as well. In such cases, knowledge including the issues
discussed in previous sections such as subjective description of and responses
to a texture, psychophysical relationship of texture perception, material
properties and manufacturing processes will be necessary. The following listed
are mainly the aspects that will stimulate the generation of a texture (either
a material texture or an image texture).
6.1
Texture
learnt from nature
Natural texture is the
texture formed by the natural forces such as a thunderstorm, wind, rain, river
etc (e.g. the stone texture), or resulting from the internal atomic structure
of substance (e.g. the diamond shiny texture) or by the original/primitive growing
mechanism of life (e.g. the texture of leaf, wood). Figure 7 shows examples of
some natural textures. No matter what kind of natural texture, such as the
random linear texture of wood, or the smooth and marvelous texture of pebbles,
or the fine, soft and wavelike desert texture, the leaf, the ice, the animal
skin, … all the natural textures not only give us an enjoyment of beauty and
harmony, but also give us abundant inspiration, as sources of creativity,
particularly in the aspect of pattern.
6.2
Texture
created from the mind, fantasy
In this case, texture
is regarded as the component of any image in people’s mind, which becomes a
graphic picture when presented via a certain media. Any images in human brain will not come from a vacuum, but from
their life experience and memory. But only the experience and memory are not
enough so that not everybody can produce an astonishingly attractive image and
become so-called ‘artist’. Free Imagination and fantasy based on that experience
is decisive factor. Here, people’s accumulated life experience and sensitivity
to art promotes each other. Examples of textures coming from this kind of
fantasy are shown in Figure 8. A deliberate strengthened training in graphic
presentation will be a worthy route to stimulate the creative thinking of a 3D
designer, particular industrial product designer in their practice.
6.3
Texture
generated from virtual reality
In authors’ opinion,
the functional meaning of things existing in virtual reality at least has two
aspects. Firstly, it is physical-reality targeted. In other words, it is the
preparatory trial or forerunner for any events in physical world, with the
purpose of as a testifier or communication for save time and expenses. Such
examples include all kinds of CAD design. Secondly, it is virtual-reality
itself targeted. As the feature of digital times, virtual reality has become a
type of culture. People can enjoy a life style by making friends, playing games
within the virtual reality. In either case, it is required that texture of
presented images has satisfactory simulation with those in the real world. A
series of computer software can make this available. In addition to vividly
simulating the textures from the physical world, the digital tool can also
produce any non-realistic texture, facilitating people’s fantasy mentioned in
6.2. Some examples of virtual textures are shown in Figure 9.
6.4
Texture
resulted from advancement of science and technology
The relationship
between a surface effect/texture and the innovation in science and technology
is two directional. Most cases might be searching for a technical method to
convert a texture from a drawing board to a 3D material surface. In these
cases, the innovative technology can give the opportunities of realising
different surface finishes and textures that were unavailable before. For
example, through in-mould coating technology (Figure 10 c. and d.), various
surface effects either for decoration or for specific functions (such as impact
resistance, crack resistance) can be realised [15]. And it can be tailor-made
in line with customer requirements. Figure 10 a. shows a texture resulted from
a photo-etching process by which a photographic image is transferred onto a
metal surface via either silkscreen or photocopy transfer. On the other hand,
in some cases, the advancement in science and technology offer unexpected
surface effects, which further stimulates creative practice. For example,
nano-technology, by manipulating the micro-size of pigment grains, dramatically
improve the look of plastics, inks, coatings, ceramics, cosmetic and personal
care products, automobile and industrial finishes.
6.5
Texture
existing in the micro-world
Usually only a few
people have a frequent contact with the micro-world. For instance, a material
scientist often looks at the microstructure of a piece of metal; a life
scientist examines the DNA composition of an organism sample. Most of other
people will neglect this marvellous world. However, information and images
within this micro-world not only can give us scientific proof supporting new
knowledge about the macro world, but also is a source of inspiration for beauty
and art. Sometimes, we can find the images from micro-world and macro-world
have some astonishing similarities. Figure 11 shows some examples of the
micro-textures observed from microscopy. In addition to appreciate the subtle
beauty of the textures, we might be able to get some lessons and enlightenments.
6.6 Texture derived from social events
Looking at the
geometrical or spatial aspect of texture, in a wider sense, we can regard
texture as the structural arrangement of the components consisting anything in
the world, including the images of social events. These events emerge here and
there from day to day. And the images of these events can also be a source of
inspiration in texture generation. Figure 12 shows the textures of the night
sky with various effects of fireworks. It is understandable that art practice
and creation has a significant relationship with social activities.
7. Conclusions
Formal aesthetics is the fundamental aspect contributing to
the whole perceived aesthetics of an artefact. Sensory adaptation and pleasure
(from colour, texture, sound etc) is the core content of form aesthetics.
Material texture plays a decisive role in the perception of the whole product’s
beauty and value. To understand and identify a texture, three streams of
information are necessary: one, the objective parameters that determine the
geometrical, physical or chemical attributes of the texture; two, the
subjective description of texture and human responses to texture through
different sensory routes; three, the psychophysical relationship between the
above two aspects. Texture can be generated or learnt from nature, mind &
fantasy, innovation in science & technology, virtual reality, micro-world
and social events.
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