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- Drawing and culturally-conditioned perception: Howard Riley
Abstract
The paper begins with a brief explanation of David Marr's computational
theory of visual perception, and his key terms. Marr argued that vision
consists in the algorithmic transformation of retinal images so as to
produce output of viewer-centred and object-centred representations >from
an input at the retinae. Those two kinds of output, the viewer-centred
and the object-centred representations, enable us to negotiate the physical
world.
The paper
goes on to suggest that the activity of Drawing is comparable as a process
of transformation: a picture is a transformation from either viewer-centred,
or object-centred descriptions, or a combination of both types of mental
representation, to a two-dimensional drawn representation. These pictures
may be described as resulting from algorithmic transformations since picture-making
utilises specific geometric procedures for transforming input (our perceptions)
into output (our drawings).
However,
a key point is made about such algorithms: they are culturally-determined.
They may be defined in terms of the procedure of selecting and combining
choices from the matrix of semiotic systems available within a particular
social context. These systems are presented in the paper as a Chart, and
are further correlated with the social functions of a communication system
such as Drawing. Thus, the paper proposes a systemic-functional semiotics
of Drawing, within which algorithms operate to realise specific cultural
values in material form.
Introduction
David Marr's computational theory of vision Along with all other major
theorists, except James Gibson (1979), David Marr (1982) assumed that
vision is the result of some kind of processing - interpretation or construction
- of the incomplete data provided by the retinal image.
The revolution
in information technology throughout the 1960's and 1970's inspired Marr
to develop a new model for explaining what happens between the retinal
stimulus and our response. A model based on the hypothesis that retinal
images could be processed by the human visual perception system in ways
analogous to the processing of input by a computer: Vision is a process
that produces from images of the external world a description that is
useful to the viewer and not cluttered by irrelevant information.
Marr & Nishihara (1978 : 269)
Marr's computational
model is an attempt to explain vision in terms of input to the
physiological system - the patterns of light falling on the surface of
the retina - and output, the information about surfaces, objects
and events in the environment which any animate organism requires in order
to survive. He shares a great deal with Gibson - for example, both agree
that incident light reflected from surfaces and edges of the environment
is re-structured as an array of differing light intensities. But Marr's
theory considers the input to be the retinal image, not an array of light.
He described visual processing as the means of producing a description
of the environment by the construction of a range of representations from
the values of light intensity falling upon the retina. Representation
here refers not to retinal or mental images but to "a formal system for
making explicit certain entities or types of information, together with
a specification of how the system does this". (Marr 1982 : 20) This is
perhaps more familiar to artists than it sounds. Any conventional semiotic
code is a formal system which has rules for selecting and combining signs
from within it in order to describe their referents. For example, the
formal system of geometric projection known as artificial perspective
is a code with rules which dictate the 2-D geometrical relationships between
lines and points of convergence in order to describe the 3-D spatial relationships
of an environment from a single, static point of observation.
The first
stage of representation Marr described as the raw primal sketch, in which
information about edges and textures of surfaces in the world is present.
The raw primal sketch represents the various light intensities in the
retinal images. These are subject to the orientation and disposition of
surfaces in the world; the reflectance properties of those surfaces; the
illumination of the scene; and of course the observer's viewpoint. All
these factors influence the retinal light intensities, and the purpose
of this earliest stage of visual processing is to separate out which factors
cause which intensities.
The full
primal sketch describes many of the shapes and textures within the retinal
image, but this is only part of the first phase of visual processing.
The main objective is to describe surfaces relative to the viewer. Marr
identified the end-product of early visual processing as a 21/2D
sketch, a viewer-centred representation, which is obtained by an analysis
of depth, motion and shading, as well as the primitive structures in the
primary sketch.
The 21/2D
sketch, describes the layout of surfaces in the world from a particular
point of view which of course is a pre-requisite for effective locomotion,
and hence survival.
An equally essential requirement of vision is the recognition of objects
and other structures within the perceived environment. In order to recognise
what object a particular processed shape corresponds to, a third level
of representation was theorised by Marr, one centred on the object, not
the viewer. This third level was identified as a 3D model representation.
The purpose of vision is to provide information about the world - a description
of what is there - from the information in the retinal images. Marr (1982
: 36) proposed that since this is "almost certainly impossible in only
one step", we require "a sequence of representations", starting with descriptions
that may be accessed from the retinal images and that act as prompts to
subsequent representations of the objective world. Marr's sequence of
representation is illustrated below adapted from Marr (1982 : 37 Table
1-1).
1. Levels of representation (Marr 1982 : 37)
Level
of Representation |
Purpose
|
Primitives |
Retinal
images |
Represents
light intensities |
Intensity
values at each point in the retinal image |
Primal
sketch |
Clarifies
the geometrical organisation of retinal light intensities |
Zero-crossings,
blobs, Terminations and discontinuities,
Edge segments,
Virtual lines, Groups, Boundaries, Curvilinear organisation |
2
1/2-D sketch |
Clar
ifies
the angle and depth of visible surfaces in a viewer-centred co-ordinate
system |
Orientation
of surface,
Distance from viewer,
Discontinuities in those two primitives |
3-D
model representation
|
Describes
forms and their organisation in space in an object-centred co-ordinate
system. This representation uses a modular, hierarchical scheme utilising
volumetric primitives and surface primitives |
3-D
models arranged hierarchically, each one based on a spatial configuration
of a few axes, to which volumetric or surface primitives are attached
|
Algorithms
Compatible with a computational theory, Marr proposed algorithms, specified
procedures for transforming input into output. He argued that the algorithms
he demonstrated on computer systems are actually implemented by the physiological
structures of neurons involved in the human visual system. His theory
has therefore had repercussions within the disciplines of biology and
physiology.
Marr and Hildreth (1980) devised an edge-finding algorithm consisting
of a series of mathematical operations performed on a computerised image.
This, they argued, was analogous to the way that the human visual system
operates at the representational level of the primal sketch.
A visible edge in the world may be specified as where a material surface
either a) changes direction along a straight, curved, or ragged contour,
or b) occludes another surface or the sky.
These conditions are specified on the retina as the boundary formed when
an area of a certain light intensity is adjacent to an area of different
intensity. A specific procedure for recognising such an edge could begin
by identifying changes, or gradients of light intensity in the retinal
image. Of course such gradients may be steep (at sharp edges) or shallow
(at blurred or ragged edges). Any change in value of light intensity across
a small masked area of the image would therefore indicate an edge. The
field of a simple cell in the visual cortex is such a masked area. (Bruce
& Green 1985 : 73) Marr claimed that many such cells, each capable of
locating specific gradients of steepness, could identify the full range
of contrast boundaries, and therefore edges, within a retinal image. But
the primal sketch is still only a description of the retinal image, rather
than of the world. The materials of the world we see, surfaces and media
such as air and water, extend over distance; some surfaces occlude others,
and of course the patterns of light reflected from and through them are
never static upon the retina: The world moves, as do we, and we constantly
need to know where we are in relation to the world. Marr and Poggio (1976,
1979) offered two algorithms demonstrating procedures by which a viewer's
position may be located with respect to the distance and disposition of
surrounding surfaces. The extraction of such stereoscopic information
from the input of the play of light upon the retinae is crucial to the
formation of a 21/2-D sketch. Marr and Poggio
(1976 : 284) suggested two rules for how the primitive descriptions obtained
from the left and right eyes may be combined to produce stereoscopic vision:
Rule 1. Uniqueness Each item from each retinal image may be assigned at
most one disparity value. This condition assumes that an item corresponds
to something in the visual world that has a unique physical position.
Rule 2. Continuity Disparity between retinal images varies smoothly almost
everywhere. Marr and Poggio utilise the Gestalt principle of continuity
based upon the cohesiveness of matter to formulate rule 2: Only a small
fraction of the area of a retinal image is composed of boundaries that
are discontinuous in depth.
Since each eye receives a different array of light, an algorithm designed
to represent a 21/2-D sketch must be capable
of co-ordinating these disparities. Marr & Poggio (1976 : 284) constructed
an explicit representation of the two rules, and derived a co-operative
algorithm which specified how a representation of the two retinal images
may be transformed into stereoscopic vision. Random-dot stereograms were
used as input for the testing of the algorithm: When we view a random-dot
stereogram, we probably compute a description couched in terms of edges
rather than squares, whereas the inputs to our algorithm are the positions
of the white squares. Marr and Poggio (1976 : 285)
Figure
2 below (from Marr & Poggio 1976 : 286) shows an example in which
the algorithm successfully allows disparity values to be assigned to elements
in each image. The shapes in the right-hand column are the computed resolutions
of the paired inputs at the left.
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In
order to verify the resolutions, the reader should focus the eyes
on a plane beyond the page so that the pair of random-dot stereograms
fuse together. It is then possible to view all four pairs at once.
We have seen how the 2¸-D sketch theorises a viewer-centred perception
of >the world, so that we may be aware of our position relative
to the surfaces within our environment. But how do we differentiate
between surfaces which form three-dimensional objects, and those
which form the landscape? Marr and Keith Nishihara (1978) proposed
a solution for this problem based upon an object-centred description
in which the object is described within a frame of reference based
on the 3-D form of the object itself. The resulting representation
of the object may be assessed in three ways: the co-ordinate system
of the representation; its primitives, Marr's term for the primary
elements of 3-D form information such as edges, boundaries, textures;
and how such information contained in the representation is organised.
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2.
Random-dot stereograms (Marr & Poggio 1976 : 286)
An object-centred
co-ordinate system is one independent of the viewer's position. A single
description of an object's spatial structure, for example based on the
object's natural axes of length, rotation, or symmetry, could then render
the object recognisable from any viewing point. Sets of descriptive elements,
the primitives of the representation, are best organised in a modular
way, as illustrated in Figure 3 (Marr & Nishihara 1978 : 278).
Marr and Nishihara discussed the process from representation to object
recognition, and in particular the importance of being able to relate
object-centred information to viewer-centred information by means of a
process of transformation (Marr & Nishihara, 1978 : 285). Marr (1982 :
25) summarised the different levels at which an information-processing
device must be understood in the following table Figure 4 Computational
theory Representation and Algorithm Hardware Implementation What is the
goal of the computation, why is it appropriate, and what is the logic
of the strategy by which it can be carried out? How can this computational
theory be implemented? In particular, what is the representation for the
input and the output, and what is the algorithm for the transformation?
How can the representation and the algorithm be realised physically?
|
3.
The organisation of shape information in a 3-D model description (Marr
& Nishihara 1978 : 278) |
Computational
theory |
Representation
and Algorithm |
Hardware
implementation |
What
is the goal of the computation, why is it appropriate, and what is
the logic of the strategy by which it can be carried out? |
How
can this computational theory be implemented? In particular, what
is the representation for the input and the output, and what is the
algorithm for thr transformation? |
How
can the representation and the algorithm be realised physically? |
4. Information-processing
device
Figure
4 David Marr emerges as the leading advocate for an indirect theory
of vision, one in which perception is argued to be the result of processing
the retinal image. James J Gibson argued for a direct theory in which
information about the world is picked up directly from the structured
array of light arriving at the eyes, and acted upon by our physiological
systems.
Both agree that the pre-requisite for vision can be described in terms
of the structure of light:
Gibson's
important contribution was to take the debate away from the philosophical
consideration of sense-data and the affective qualities of sensation
and to note instead that the important thing about the senses is that
they are channels for perception of the real world outside, or, in the
case of vision, of the visual surfaces. He therefore asks the critically
important question. How does one obtain constant perceptions in everyday
life on the basis of continually changing sensations? This is exactly
the right question, showing that Gibson correctly regarded the problem
of perception as that of recovering from sensory information 'valid
properties of the external world'. Marr (1982 : 29)
The two theories
differ over their explanations of how our physiological apparatus deals
with the incoming light. Gibson claimed we resonate directly in response
to the ecologically-structured information contained within the arrays
of light arriving at our eyes. Some invariant aspects of the structured
arrays specify lower-order information about surfaces - their distance
and slant for example. Other invariants, yet to be defined, are supposed
to specify higher-order information about objects and what they may afford
us. There is therefore no requirement in Gibson's theory for an intermediate
level of information-processing. The reception of affordance information
leads automatically to active response. The theory does not address how
resonance is accounted for physiologically. Marr's theory proposes three
levels at which perception needs to be explained; the ecological, and
the physiological, with a level of mediation in between, an algorithmic
level, in Marr's term, which organises the ecologically-conditioned information
arriving at the eyes in a way suitable for representation by the physiological
system. In Marr's opinion, the omission of such a level of mediation -
information-processing - invalidates Gibson's theory of direct perception:
Gibson's....fatal
shortcoming...results from a failure to realise two things. First, the
detection of physical invariants, like image surfaces, is exactly and
precisely an information-processing problem. And secondly, he vastly
underrated the sheer difficulty of such detection. (Marr 1982 : 30)
Detecting
physical invariants may be difficult, but we are able to do it. Marr's
difficulty may be in demonstrating computationally how it is done. Marr's
important distinction between a viewer-centred representation of a scene
and an object-centred representation allows interesting insights into
the ways people have developed systems of geometry in order to make visual
records of these various perceptions.
David
Marr's computational theory of vision related to Drawing
In the Introduction
some of the terminology of machine vision research which Marr (1982) utilised
and developed was defined and discussed. Here it will be necessary to
introduce some other terms from that discipline in order to specify the
differences in discussion of the visual world, or scene, and two-dimensional
material representations of it, pictures. The simplest elements making
up the material world, scene primitives such as edges, boundaries, corners,
texture units and surface segments, are transformed through drawing into
picture primitives such as lines, line-junctions, points and regions (Willats
1997 : 290) Marr argued that vision consists in the algorithmic transformation
of the retinal images so as to produce viewer-centred internal representations
and ultimately object-centred internal representations which enable us
to negotiate the physical world. Using such terminology, Drawing itself
may be considered as a process of transformation; from those object-centred,
internal 3-D model descriptions of a scene, to a two-dimensional external
representation, or picture. A picture too may be either viewer - or object-centred,
depending on the algorithm which specifies its particular system of geometric
projection. Some of these algorithms may describe the way light is transmitted
through space - for example, the algorithm that specifies an artificial
perspective projection. Some of them most certainly do not - transformation
rules that specify the reversal of optical rules are evident in Drawings
- for example, reverse perspective, or pictures based on topological transformations.
One purpose of such pictures is to communicate the experiences of seeing,
and actually, drawing may enable contemplation of the very process of
transformation from viewer-centred to object-centred representations.
Apart from informing the activity of drawing itself, Marr's methodology
adapted to the study of children's drawings has been able to provide insights
into how they develop through a series of stages identified with children's
developing awareness of themselves and their relationship with the world
of objects and events.
John Willats'
adaptation of Marr's theory
Willats (1987,
1995, 1997) has been able to forward a consistent theory of children's
drawing development by treating them as "information-processing devices
for producing pictures". (Willats 1995 : 28) He proposes that the ways
people convey their experiences of the world through Drawings may be described
in terms of two systems that afford the Drawer access to compositional
choices: the drawing system, and the denotation system. Although Willats
does not refer to Halliday (1985) or O'Toole (1994) and makes no reference
to systemic-functional semiotics in his writings, his intention appears
remarkably similar: "...
I shall
try to show that analysing pictures in terms of these two representational
systems (the drawing system and the denotation system) can be useful:·.I
shall argue that differences in the representational systems found in
different periods and cultures, and the changes that have taken place
in these representational systems during the course of art history and
that take place during the course of children's drawing development,
are mainly determined by the different functions that representational
systems are called on to serve". Willats (1997 : 1-2)
Willats'
proposal is derived from Marr's and Nishihara's work on what they called
the representation of "three-dimensional shapes" or form. They identified
three aspects of a representation's design:
"(i) the
representation's co-ordinate system (ii) its primitives, which are the
primary units of shape information used in the representation, and (iii)
the organisation the representation imposes on the information in its
descriptions". Marr & Nishihara (1978 : 269)
Viewer -
and object-centred co-ordinate systems used in drawing, and Willats' contributions
to their classification may be described by the term Drawing conventions.
Their function is to transform three-dimensional spatial relationships
in the scene into two-dimensional geometrical relationships on the picture
surface. The function of Willats' denotation systems, however, is to transform
scene primitives into picture primitives. The distinction between the
geometric relationships on the picture-plane and what they denote is crucial,
since the two are easily conflated. For example, in our everyday usage
of language, lines on a Drawing surface are referred to as edge of objects;
depicted two-dimensional shapes are described as three-dimensional forms;
two-dimensional patterns are spoken of as three-dimensional texture. Gibson
identified this problem when he wrote of the duality of seeing; the perception
of the spatial world of undulating surfaces, edges, colour and texture
as opposed to the perception of the world of signification, which of course
includes drawings.
Denotation
systems, scene primitives and picture primitives Scene primitives are
such things as edges, corners, surfaces or 'generalised cones'. Marr (1977
: 442-3) defined a generalised cone as "the surface swept out by moving
a cross-section of fixed shape but smoothly-varying size, along an axis".
Willats prefers the term extendedness in one, two and three directions
to describe such volumes. Scene primitives may be zero-, one-, two-, or
three-dimensional. A zero-dimensional scene primitive may be a corner-point
of an object. An edge may be a one-dimensional primitive, a surface may
be a two-dimensional primitive, and a volume or generalised cone may be
a three-dimensional primitive. The activity of drawing transforms these
scene primitives into picture primitives, and Willats (1997 : 93) classifies
denotation systems as being based upon such picture primitives, as points,
lines or regions. Picture primitives may be zero-, one-, or two-dimensional.
A zero-dimensional picture primitive representing a corner, may be the
point of a junction between two lines. A one-dimensional picture primitive
representing an edge, may a line. Two-dimensional picture primitives,
representing surfaces, are regions, or faces. (A region in a Drawing is
Willats' term for the projected shape of a three-dimensional object in
a viewer-centred drawing system; a projected shape of an object in an
object-centred drawing system he terms a face) Such a concise terminology
deriving from Marr's approach and differentiating between viewer - and
object-centred Drawings, scene and picture primitives, has allowed Willats
to offer critiques of other theories of children's drawing development,
and to propose an alternative.
Marr, Willats,
and children's drawing The most generally accepted explanation of children's
drawing development until Willats' was that young children draw what they
know, and older children draw what they see. This argument, put forward
as early as A. B. Clark (1897) was developed by G. H. Luquet (1913, 1927)
into a theory of intellectual realism versus visual realism. The change
from intellectual to visual realism is deemed to occur between the ages
of seven and nine years. Willats (1997 : 288) has suggested that the distinction
between intellectual and visual realism may be interpreted as that between
object-centred and viewer-centred internal descriptions as theorised by
Marr. Jean Piaget and B. Inhelder (1956) inherited Luquet's theory, but
added their insight about the child's development of space conception
based upon invariant geometry, in which certain spatial relations remain
invariant over transformations from one co-ordinate system to another.
The classes of invariant geometry form a hierarchy in which each one is
a special case of the one before (above) it:
Stage
1 Topology
Stage 2 Projective geometry (perspective)
Stage 3 Affine geometry (oblique projections)
Stage 4 Metric geometry (orthographic projections)
The number of invariant features increases from stage 1 to stage 4, so
that features remaining invariant under transformation in Metric geometry
include: size, shape, angle relationships, straightness, parallelism,
length, ratio of length, area, and others. Piaget and Inhelder suggested
that progression from stage 1 to 4 could account for the child's development
of a conception of space, and therefore the development of drawing ability.
However, Willats (1977) showed that in practice the developmental sequence
was the reverse: Children aged between 5 and 17 were asked to draw a table
with various objects on it from a fixed viewpoint.
Figure 6 (from Willats 1997 : 11) illustrates typical results.
6. Children's drawings of a table (Willats 1997 : 11)
Figure 6
The Drawings and the children's ages were classified as follows:
b No projection system (Topological); average age 7.4 years
c Orthographic projection (Metric geometry); average age 9.7 years
d Vertical oblique projection (Affine geometry); average age 11.9
years
e Oblique projection (Affine geometry); average age 13.6 years
f Na•ve perspective (Projective geometry); average age 14.3 years
g Perspective (Projective geometry); average age 13.7 years
This experiment demonstrated that there seems to be a clear sequence of
development from orthographic, through oblique, to perspective drawing
as the child grows older. In Marr's terminology, Willats' experiment shows
that children begin drawing their surroundings using object-centred descriptions,
and progress to viewer-centred descriptions. Willats' important contribution
is to point out that the reason other theories of development of children's
drawing seem to ignore the changes >from object-centred drawings to viewer-centred
drawings is because they assume that both input and output are view-based
regardless of age. The weakness of these arguments is that they do not
recognise the possibilities of any algorithms that would allow the transformation
of view-based input to object-centred drawings as output, and subsequently
from object-centred drawings to viewer-centred drawings.
Algorithms - the rules governing the transformations from one kind of
drawing to another - are culture-specific, and indicate the Drawer's ideological
positioning, as well as their mental positioning in relation to the scene
depicted. Willats' insights are important to the teaching of drawing,
since they allow the opportunity to explore how the variety of ways in
which selections from the range of drawing systems and denotation systems
may be combined to produce the cultural variety of drawing styles. This
opportunity will be explored shortly, with discussion about how such selections
and combinations operate semiotically to make visible the ideologies and
belief-systems of the culture in which they are produced. Margaret Hagen
(1986) presented an interesting conundrum when she argued firstly against
any notion of a hierarchy of drawing styles (1986 : 271) "·.development
in art does not take place historically or culturally, ·.no specifiable
pattern or set of characteristics distinguishes earlier styles >from later
ones", and then later (1986: 279-280) "In younger children, Orthogonality
is commonplace;·In older children Affine and Projective systems also make
an appearance·." In the first instance, her statement comes after, and
in support of her argument that the way people draw is a function of their
particular cultural experiences. Could it be that the process of development
that both Hagen and Willats observed in the Drawings of children simply
evidence of a growing awareness of their position as individuals within
the culture? Such self-awareness may be indicated by the development from
object-centred Drawings to viewer-centred Drawings. Only after children
have achieved this state of awareness do their Drawings become subject
to the wider demands of social conventions and cultural constraints, and
the wider range of functions that Drawings are called upon to serve
Marr and
Gibson: common ground
Hagen's work
was heavily influenced by Gibsonian theory. Gibson's explanation of the
development of children's drawing challenged the traditional argument
that children first draw what they know and then develop to draw what
they see, by pointing out that if the argument is to be couched in those
terms, then they should be the other way around. Gibson attempted to by-pass
that false antithesis of seeing versus knowing by claiming that children
first draw those invariant features of objects that they notice first,
and that their drawings alter as their awareness of what they notice expands.
In doing so, Gibson appears to be explaining what in Marr's terms would
be the transformation process from raw primary sketch through the 2¸-D
sketch to a 3-D model description, and finally to pictures. It may be
that as children's awareness of their positioning in the world develops
along with hand-eye co-ordination, so does their ability to display their
object-centred internal descriptions through the making of object-centred
pictures, and later viewer-centred pictures. Marr's and Gibson's positions
share common ground. For example, here are several principles laid down
by Gibson (1950 : 6) that appear to be consistent with Marr's theory.
The main principles follow from the hypothesis that there is no perception
of space without the perception of a continuous background surface.
1. The elementary impressions of a visual world are those of surface
and edge.
2. There is always some variable in stimulation which corresponds to
a property of the physical environment (for example, the variable stimulus
corresponding to 'surface' is probably a textured retinal image; stimulus
for distance or depth over a continuous surface may be an increase or
decrease in the density of the texture of the retinal image. The variable
stimulus for 'edge' is probably the contrast boundary between two different
light-intensities upon the surface of the retina).
3. The
stimulus-variable within the retinal image to which a property of the
environment corresponds need only be a correlate of that property, not
a copy of it (Gibson explains that solidarity and depth in reality cannot
have any replica in the two-dimensional retinal image, but they may
have correlates there).
4. The
inhomogeneities of the retinal image are analogous to the variables
of physical energy and this means that the pattern of retinal image
can be considered a stimulus.
Such principles
indicate a closer correlation between Gibson and Marr than is generally
acknowledged, and it is these correlations that afford the opportunity
to adapt both theorists within a wider model that relates perception theory
and visual communication theory.
The visual
aesthetic process of production
Consider
the relationship between an individual piece of work and the state of
the culture within which it is located: The individual piece may be expressed
through identifiable conventions which may be taken to constitute the
'hallmark' of the period, or may challenge those conventions. It is to
explore such relationship between individual expressions and cultural
conventions that Raymond Williams (1968) invented the term "structure
of feeling", A structure of feeling describes the ideological aesthetic
construction through which we make sense of the unique within the generalities
of a period's social conventions. The making visible of any idea requires
an inception stage, in which social concepts and individual percepts are
codified in material form. What I term the visual aesthetic process is
an ordering of visual perceptual relations deemed appropriate by the producer
for transforming into visible form some aspect of the socio-cultural values
of the particular social and cultural context.
(Seeing) |
|
(Knowing) |
|
(Producer) |
|
(Viewer) |
PERCEPTION
Individual
activity through which information about the world is taken up
|
|
CONCEPTION
The
'filtering' of perceptual information via social constructsC
|
|
INCEPTION
The
encoding of concepts in material form
|
|
RECEPTION
Making
sense of the work within a social contex
|
Figure
7. The visual aesthetic production process
At the inception
stage, the semiotic requirements for visualising social ideology will
determine the selection and combination of drawing elements:
SELECT Elements of drawing: |
|
COMBINE Combinations of elements produce: |
|
COMMUNICATE
Combinations stand for physical and emotional experiences of the world:
|
point
line
shape (2D)
texture
tone
colour
plane |
|
contrast
proportion
scale
pattern
rhythm |
|
spatial
depth
force
direction
movement
volume, mass, weight
balance
symmetry
structure
form (3D)
surface properties
observer's position(s)/mood, attitude |
The combinations
in the above chart are of course universal. They can be seen at work in
all visual imagery in every culture. But how these combinations come to
represent experiences of the world is very much culture-specific. What
is noticed about distance-relations for example may be represented using
proportion and scale encoded in a system of geometry deemed appropriate
to that society's world-view: For example a society with no concept of
egocentricity would have little need to develop an artificial perspective
which represents distance relations from a static, one-eyed central viewpoint.
The social
semiotics of drawing
In the materialist
sense, Drawings are produced through the selection and combination of
particular surfaces, drawing tools, and the marks resulting >from their
interaction. But semiotically speaking both producers and viewers of Drawings
take up positions, adopt attitudes, points of view which are influenced
by their positions within their sets of social relations. Such an ideological
positioning involves a definite way of using signs (a semiotic), and a
structured sensibility (an aesthetic) both grounded in a particular system
of social relations. How the producer selects and combines the compositional
elements of the Drawing, and how the viewer relates to that Drawing are
both functions of the social contexts in which the work is (re) produced.
But to simply say that Drawings reflect social structure is too passive.
Drawing not only expresses the social context but is part of a more complex
dialectic in which Drawings actively symbolise the social system, thus
producing as well as being produced by it. Variation in ways of drawing
is the symbolic expression of variation in society. Drawing systems are
produced within society, and help to produce social form in their turn.
This dialectical relationship is what Michael Halliday (1978 : 183) discusses
in the phrase "social semiotic".
Varieties
of drawing Of the two kinds of variation in language identified by Halliday
(et.al. 1964), dialect expresses the diversity of social structure, and
register expresses the diversity of social process. Whilst the meaning
of dialect may be commonly understood, register may require further discussion.
It refers to the fact that language usage varies according to the situation
in which it is used. In terms of drawing, register would refer to the
variation in selecting and combining visual elements according to the
purpose for which the drawing was produced. The social system (the Culture)
can be represented as a construction of meanings - as a semiotic system.
And the meanings that constitute the social system are exchanged through
the rich variety of semiotic codes developed by humans of which Drawing
is one.
From this social semiotic perspective, any social context may be understood
as a temporary construct which may be mapped in terms of three variables
which Halliday called field, tenor, and mode.
Field
of social process - what is going on at the time of production of the
drawing.
Tenor of social relationships - the type of drawing we produce
varies according to the level of formality, of technicality, of need
for clarity of communication, etc. It is the ROLE relationships - the
drawer, the subject matter, the viewer and their inter-relationships
- that affect the variations.
Mode of symbolic interaction - in the sense that how we draw
varies with our attitude: An attitude of objective observation may produce
drawings in a realistic mode; emotional disturbance may be realised
in an expressionist mode; absentmindedness in doodling mode. An attitude
attuned to the necessity of clear communication may produce drawings
in a highly conventional mode specified by British Standards or professional
bodies.
The functions
of drawing Any code of communication has three main functions: to convey
some aspect of our experience of the world; to both express our attitude,
mood regarding our experience and to position the receiver in terms of
mood and attitude; and thirdly to structure these two into a coherent,
perceptible form. These first two functions may be labelled the experiential
and the interpersonal. The third may be termed the compositional function.
The parameters
of social context; field, tenor, and mode are systematically related to
the functions of the semiotic system. In fact, those meanings that constitute
our understanding of any particular social situation are made visible
through the selection and combination of elements within the semiotic
system.
Parameter
of social context |
Function
of drawing through which a social situation is realised |
Field
(what is happening) |
Experiential
function |
Tenor
(who is taking part) |
Interpersonal
function |
Mode
(what part the semiotic code plays) |
Compositional
function |
This is the
basis of a model which may theorise how Drawings operate within a social
context. Halliday (1973) elaborated upon this basis to provide a model
which identified the systems of choices from which specific selections
may be related to the functions of language in specific social contexts.
Michael O'Toole (1990) was the first to demonstrate the power of Halliday's
insights when they are applied to the analysis of painting. He offered
a systemic-functional model of painting in which he substituted the labels
Representational, Modal, and Compositional for Halliday's original terms
Ideational, Interpersonal, and Textual describing the three functions
of language. Later O'Toole (1994) demonstrated the versatility of Halliday's
model by adapting it to theorise how sculpture and architecture may be
made sense of within their social contexts. It is proposed that a systemic-functional
model of the ways that Drawings may be produced and viewed would be immensely
useful for studio discussion and drawing practice.
A systemic-functional
semiotic model for drawing
Such a model
is proposed in Figure 8 where the Experiential function of drawing relates
to a drawing's ability to represent some aspect of our experience of reality;
the Interpersonal function deals with how Drawings may exhibit the maker's
attitude and may position the viewer in terms of attitude and mood. The
Compositional function deals with the systems of selection of media, surfaces
and marks that combine to make visible, to realise the other two functions
in material form. The term levels of engagement refers to the hierarchical
layering within which engagement with the Drawing is possible. The matrix
of systems of choices emphasises the systemic nature of the model: these
ranges of available choices do not simply allow meanings to be negotiated
at any single functional level, but affect all functions as a whole. Social
meanings to do with the Drawer's and viewer's experience within the field
of the real world, and also the tenor of the relationship between Drawer
and viewer are all realised simultaneously through the systems of Theme,
Modality, Geometry, etc. Choices from these systems are realised as particular
modes of drawing which are themselves realised as appropriate combinations
of drawn marks upon a surface. In this chart, the varieties of geometries
derived from the variety of ways of seeing, become some of the systems
available to the Compositional function in order to realise - make visible
- the Interpersonal and the Experimential functions. Also, Willats' denotation
systems discussed earlier made up from selections and combinations of
picture primitives, may be integrated within the systems of choices available.
Combinations of selections from the available systems of compositional
choices allow the Drawer to give visible material form to modulations
of their physical, emotional and imaginative experiences of the world.
Reciprocally, those combinations are modulated through and related to
the viewer's own experiences of the world. Thus the proposed model may
facilitate both a means of putting sense into Drawings, and making sense
out of Drawings.
LEVELS OF
ENGAGEMENT . FUNCTIONS OF DRAWING
COMPOSITIONAL
. INTERPERSONAL . EXPERIENTIAL
The Drawing as displayed in context MATRIX OF SYSTEMS OF CHOICES
- Inter-textuality
- Systems of Geometry: persp. orthographic, oblique, inverted persp., & topological
- Primary or secondary geometries
- Size and format of options, including framing devices
- Location options
- Systems of modality: Mood, attitude, positioning, viewer-centred, object-centred
- Public/Private
- Intimate/Monumental
- Systems of theme: Physical, emotional, imaginative experiences. narrative, Historical genre
- Realistic/Abstract á Interplay between objects, poses, events Sub-divisions of the Drawing's surface
- Gestalt relationships: horizontal, vertical, diagonal axes
- Proportional relationships
- Tonal passages (aerial persp.)
- Systems of gaze: Eye paths, focus points
- Dynamic/Static
- Calm/Excited
- Balance/Unbalanced
- Sub-themes:
- Central/Supportive to narrative
- Actions, poses, events, objects
Combinations of drawn marks
- Relative size of marks
- Relative orientation of marks
- Relative position of marks
- Colour, tone and texture contrasts
- Pattern
- Rhythm
- False attachments
- Deep/shallow range of depth illusion
- Foreground/Background range of positioning
- Stability/Instability
- Repetition
- Scale
- Distance between surfaces
- Direction
- Transparency/Opacity of surfaces
- Atmospheric conditions
- Quality of light
- Time of day
A drawn mark
- Size relative to picture surface
- Orientation relative to picture surface
- Position relative to picture surface
- Combination of surface texture and drawing medium
- Picture-primitives
- Phychological orientation
- Range of textural meanings: wet/dry; hard/soft; matt/gloss
- Denotation level of meaning
- Spatial depth
- Effects of gravity and other forces
- Effects of light and water upon material surfaces
- Scene primitives
MATRIX OF
SYSTEMS OF CHOICES
Figure 8
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