TOWARDS COMPUTER SUPPORTED DESIGN FOR AESTHETICS Willem G. Knoop, Ernest J.J. van Breemen, Imre Horváth, Joris S.M. Vergeest Delft University of Technology Sub-faculty of Industrial Design Engineering Jaffalaan 9, NL-2628 BX Delft, The Netherlands Phone: +31 15 278 3437 Fax: +31 15 278 1839 E-mail:
[email protected] Binh Pham School of Information Technology & Mathematical Sciences University of Ballarat PO Box 663 Ballarat, VIC 3353, Australia Phone +61 3 5327 9286 Fax +61 3 5327 9289 Email:
[email protected]
98ME075 ABSTRACT Although attempts have already been made, computer support of styling is still in its infancy. Based on the functionality of present CAD systems, computer support of car styling will be rather moderate in the near future, especially when fast representation and alteration of early shape concepts are considered. It is assumed that, by developing shape conceptualisation methods based on a better understanding of the styling design practice, early stage car development would benefit from the advantages of electronic product modelling. This paper presents a novel computer-oriented methodology of design for aesthetics. The Authors focus on the issues related to a practical coupling of aesthetic intents and shape characteristics, following the analogy of information communication. In this two-way process, they distinguish statistical, syntactical, semantical and pragmatic levels. The analogy helps to understand the core problem of design for aesthetics and supports the elaboration of a quasiformalised methodology that serves well as a base of computer tool development. Such tools implicate opportunities to tailor car designs to niche markets when theoretical, technical, and educational issues are addressed carefully, together with appropriate management of company cultural changes. 1
INTRODUCTION
The importance of aesthetics in automotive industrial design is evident. Only very few people buy a car based on technical performance and costs only. Usually appearance, comfort and aesthetic appreciation play a crucial part in the buying process. Design for aesthetics, together with design for ergonomics, intelligence, user friendliness, adaptability, etc. are the fields which will surely be in the focus of the research and development in the near future due to their role in enhancing product acceptance. The development process of cars will alter when the need grows to tailor cars to more diverse groups of target customers. Aesthetic characteristics that are more diverse will have to be incorporated into the design of cars. Therefore, stylists need a method to define, use, and communicate aesthetic intents, supported by computers to assess the aesthetic appreciation of the customers related to the shape of the car.
Another problem field is to discover how much specific aesthetic appreciation by customers changes when an engineering-induced alteration is necessary. The advancement of a car design towards manufacturing places high demands on the communication between the simultaneously working groups. When a methodology exists to assess the impact of a change to the aesthetic appreciation of the design by target customers and the styling department, engineers will be able to optimise their work on a higher level. In spite of their important role, stylists are still waiting for computer support to grow beyond its infancy. The task of industrial designers and stylists is sometimes called impossible to support by computers [Hosaka 1992]. In one sense, this statement is true, for near future CAD-system functionality is moderate when it comes to supporting or substituting the tasks that human beings do so well. On the other hand, computers should be used to perform the tasks people are having difficulties with, like keeping an overview over large amounts of information and checking relations between dozens of aspects. The focus of our research into computer-aided conceptual design (CACD) is on the conversion process of mental images to shape representation. To enable this in design for aesthetics, the following items are needed: • A proper understanding of the work of stylists, including the ability to process a rich and diverse language of linguistic and graphical elements, • A computer oriented methodology for design for aesthetics, • Alternative (non-geometric entity oriented) natural input mechanisms of shape, • Flexible computer internal representation of the initial shapes, • Powerful image manipulation techniques, and • Free-form physical prototyping techniques We are investigating these issues, as shown on our web pages, see [ICA 1998] A computer oriented methodology and further research into understanding the relation between shape, aesthetics, and psychological aspects should be developed in this young discipline of design for aesthetics [Pham 1996]. The most intriguing issue of such a design for aesthetic methodology is how to implement a translation or mapping between two universes: the space of aesthetic characteristics and the space of shape characteristics. The correspondence between elements (or groups of elements) of the two spaces is not straightforward. It can be apprehended only with the involvement of psychological aspects, as it is strongly influenced by cultural, personal, sociological, etc. factors. Designers cannot influence the experience or mood of the person that will interact with their design. They cannot fully control customer responses. However, they can alter the shape and influence appreciation to a certain amount, but appreciation is a design aspect that does not stand alone. The next chapter will elaborate on how shape and aesthetic characteristics interrelate with other aspects of a product and what the fundamentals of our research are to investigate computer support of design for aesthetics. 2
TOWARDS A BETTER UNDERSTANDING OF DESIGN FOR AESTHETICS
Design for aesthetics plays a significant role in automotive product development processes. It is usually referred to as styling. It is a specialisation, clearly separated from engineering, with the task to determine the appearance and identity of new cars [Tovey 1997]. The stylist’s task in design for aesthetics is of particular interest for computer support, especially because of the apparent need to communicate with engineering departments, that make use of computers extensively. Stylists are designing products in a process that in most companies is clearly outlined. They have to present their results in pre-specified formats, on carefully planned management intervention points [Tovey 1992]. Designers go through the design cycles of analysing (sub-) problems, generating ideas for (sub-) solutions, and combining them into a holistic solution. They pay attention to all aspects that are important in the development of
cars, e.g. ergonomics, manufacturability, technological constraints, aesthetics, and sustainability. This means that design for aesthetics never stands alone, and should always be related to the other aspects in the whole product development process. Not all aspects are equally dominant, important or costly (in time or money), therefore design teams try, conscious or not, to obtain a "balanced comprehension" of the influences and interactions of aspects (Figure 1). At any given moment in the development process, this "balanced comprehension" allows a designer to judge the relative importance of aspects. It helps to track which current solutions are satisfactory and helps designers to choose what action to take next. Customer behaviour
Aesthetics Product Concepts
Ergonomics Materialisation Modeling
Functional Assemblability Physical Manufacturability Design aspects
Reliability Manipulability
Balanced Comprehension
Structural Shape
Ideation
Material Sustainability Appearance Cost / Price Marketing Environment Recycling ...
Figure 1: The role of balanced comprehension in conceptual design
In search for computer support of the design for aesthetics process, many issues have to be resolved. The graphic language used by stylists is hard to represent in a computer. It is notoriously difficult to assess and formalise their typical way of working, communicating, and using both linguistic and graphical ways to connote feelings about ideas and concepts. It is important to link the styling process to the engineering process with computer systems. Those systems must be dedicated to the task of stylists but also to communication with engineers. The advantages of using an integrated computer support system over traditional car development are discussed by Knoop and Munnich [1994]. However, it also turned out that the coupling of Styling and Engineering has to be “loose” enough to assure that styling intentions are present in the final product [Knoop and Munnich 1995]. A computer oriented design for aesthetics support system should be capable of: • Capturing the aesthetic intents of stylists, based on knowledge of target customers, which are also linked to marketing intelligence and major strategy of the company. • Finding solutions in which these intents are translated into new concepts of products. The basic question is "how can we map shape characteristics of products to the intentions they are to express". • Testing or assessing the level of success in designing products that have the desired impact on the target consumer group We performed a survey to find approaches to link aesthetic intents and shape. Our review of literature has revealed that some attempts have been made to relate customer appreciation of
Figure 2: The Koenderink method results in 3D-representations of shapes perceived by subjects. This figure shows differences between perceived shapes of a sketch and the real product
aesthetic properties of products to the shape of those products. We distinguish two groups of studies with either a phenomenological or a systematic approach. The first is an approach in which phenomenological information about customer responses is used to intuitively incorporate shape characteristics in a product, in order to evoke desired responses. The second is an approach in which a deep understanding is looked for, of all the factors involved in the influence of shape on the resulting appreciation of products. An example of the phenomenological approach is reported in [Desmet and Tax 1998] in which mobile telephones are designed based on desired feeling-based responses. In-depth interviews provided information about two target-customer groups, which led, with the help of collages, many stimulating ideas and concepts, to the successful design of mobile telephones with an emotional extra. The systematic approach was illustrated by a study the INSTANCE project (BriteEuRam no.3, project 95/2151), in which the Koenderink method was used to investigate the relation between aesthetic appreciation and the shape of car bodies. This method provides a subject with a representation of a car, and asks the subject to indicate the surface normal on many places on the model, to assess the perceived shape of the model, see also Figure 2. We think it is important to develop a theory that gives both • the desired deep understanding of the influence of all involved factors in aesthetic appreciation of products, and • insight in the complete loop of determining aesthetic intents, develop ways to design the shape of products accordingly and to evaluate the results. Our approach to accomplish this is analogous to the theory of information communication. This analogy will be explained in the next chapter. 3
FORMALISING DESIGN FOR AESTHETICS
To process aesthetic intents in computers, and to study the process of integrating aesthetic intents in designs of new products, we first have to clarify some terms. We distinguish three basic characteristics that express the aesthetics of a product: shape, composition and physical attributes. High-level characteristics such as style or fashion may be dealt with by expressing them in terms of these three basic characteristics [Chen and Owen 1997]. Often form and geometry are also used to indicate shape, but these are ambiguous terms. Even Webster’s Dictionary describes them in a tautological way. We see geometry as the lowest level explicit description, a form of mathematical documentation of a 3D point-set in space. Geometry can only support the aesthetic-shape mapping process. One level above the geometry we find form, which is, according to our understanding, a categorical representation of global properties of the geometry. It is a more generalised descriptive term (e.g. a triangle). Form typically influences the aesthetic characteristics. Shape has to be seen on a higher level than geometry and form. In contrast to
Shape feature Shape Expresses Composition Physical Attributes Aesthetic characteristics
Influences Form Triangles
Supports Geometry
{(x1,y1) , (x2,y2) , (x2,y2)}
Figure 3: Product characteristics and the interaction with aesthetic characteristics
the global characteristics, shape is defined as the totality of local characteristics of the geometry. Therefore, shape is an abstract generalisation of the local geometric properties. The local geometric properties are shape features that form the basis for shape manipulation on a semantic level. An example of shape is the star-like object in Figure 3. This object is a set of sharp edges (the local shape features) which indeed make the object a star. In relation to aesthetic characteristics, the role of shape is to express them. Referring to the above definitions composition expresses how shape features are arranged and therefore acts on the same level as shape with respect to the aesthetic characteristics. Guidelines for good compositions which have been recommended by artists and designers for attaining visually pleasing and interesting objects, e.g. [Ruskin, 1971], may be deployed for analysing and comparing aesthetic characteristics of design. Physical attributes such as colour, texture, lighting conditions or material properties also influence aesthetic characteristics, in a similar way as shape does. In fact they add different attributes to the shape and contribute to the total impression of an object. Although the terms to describe aesthetic characteristics are rich and complex, we believe that the essence of these terms can be related to the three basic characteristics of objects, individually or in combination. Our aim is to provide a general methodology to include aesthetic aspects into product design. It seems to be practical, for the time being, to concentrate on how these basic characteristics of a product influence its appreciation, and to leave out other aspects. A theory of design for aesthetics has to explain how meaning and beauty are communicated by a particular manifestation of an object. The principal medium of that communication is the shape of an object. Shape, together with composition and physical properties expresses aesthetic characteristics that result in certain aesthetic appreciation. In the context of this paper, recognised influences like culture, experience, and emotions of subjects are assumed constant. To provide the means for formalisation, we introduce a model of design for aesthetics based on the analogy of information communication [Hering et al, 1995]. The model reflects the understanding that design for aesthetics is a two-way communication between the space of aesthetics and the space of design variables. In communication of information the semantic content is carried by digital/analogue signals [Schotz-Reiter, 1992]. In communication of aesthetics, the meaning is conveyed by the shape,
composition and physical properties. However, these semantics are implicit and the meaning and effects cannot be completely separated from their interpretation. Consequently, a methodology of design for aesthetics has to form a closed loop with two parts that (a) provide support to understand how shape evokes feeling based responses in the case of a particular product and a specific group of customers, and (b) enable designers and stylists to communicate their aesthetic message and achieve emotional appreciation by certain shapes. Four levels have been identified in the information transmission process: (a) statistical, (b) syntactical, (c) semantical and (d) pragmatic. In addition, recent studies circumscribe a fifth level [Meadow and Yuan, 1995] that is orientated to explain what comes beyond the practical use of communication, what possible developments there are. In the future, it may deepen our comprehension over the process of communicating aesthetic characteristics. The activities to explore and understand the customer response to aesthetic impression and to create the features of a product with expected aesthetic appreciation form a closed loop. Based on the analogy of information communication, a hierarchy of levels of aesthetic communication can be identified in the streams of activities to and from the space of design variables. This will enable us to find the objectives and content of the activities. A methodology for design for aesthetics has two parts similar to the two directions of communication in Figure 4. In the exploration part of the loop (the bottom part of figure 4) which is targeted to understand how meaning and beauty interacts with people, a kind of experimental process is executed. Different variants of a product of different observable aesthetic characteristics are presented to the customers in either physical or virtual forms [Spooner and Hardwick, 1997]. Potential customers are asked to select those objects that can be sorted into the same cluster due to their aesthetically similar or resembling shapes. Only a fuzzy clustering is possible since the objects can be sorted into more than one cluster based on their aesthetic characters of different dominance. These activities relate to the statistical level of communication. The next step is the exploration and naming of aesthetic characteristics common for the products in a cluster. The users are asked to describe the aesthetic properties they observed and recognised as well as to select depictions of the feelings the objects individually evoked in them. This is the Semantical level
Pragmatic level
Controlling by user experiments
Finishing the product image
Syntactical level
Designing local shape features
Statistical level
Designing global shape features
Designing of the initial shape
Process of designing aesthetically pleasing products {F } 1 {F } 4
{F } 2
{V } 2
Space of design variables
Space of aesthetic characteristics
{V } 1
{F } 3
{V } 3 {V } 4
Process of understanding how aesthetics relates to shape Experiment with typical objects
Clustering objects based on feelings
Statistical level
Exploring common characteristics
Syntactical level
Identifying shape characteristics
Semantical level
Understanding the influence of shape
Pragmatic level
Figure 4: Model of design for aesthetics with two directions, each having four levels of communication
syntactic level of communication. Then, the explored aesthetic characteristics of the objects and the correspondence to the feeling based responses are analysed. This way clues are formed for the possible relationship. It forms the semantic level in aesthetic communication. Since the shape is influenced by the less dominant aesthetic characteristics too, formulation of relations cannot be deterministic. On a pragmatic level, the adequacy of matching the aesthetic characteristics against global and local shape properties is tested. The shape properties are modified and the potential users are asked to judge whether the previously recognised aesthetic characteristics become stronger or weaker, or remain intact. This instituted knowledge can be formalised in the knowledge base of a computer-aided design for aesthetics system. The creative part of the loop (the top part of Figure 4) is dedicated to designing aesthetically pleasing products systematically. The involved mapping is directed from the space of design variables to the space of aesthetic characteristics. As a starting step, designers generate initial shape concepts that fulfil functional requirements and describe them from geometric, topological and morphological point of view. This specification is again a statistical level of communication. Then the shape concepts are further refined globally to provide observable shape characteristics (e.g., type, extent, proportions, morphological articulation, distortion, number of components, etc.). Additional design aspects (e.g., material, colour, texture, and graphics) are also considered. It places us on the syntactical level of communication. Afterwards, the local properties are manipulated in order to incorporate subject related aspects (e.g., style, fashion, human preferences, etc.). This is actually the semantical level, which extends to the manipulation of additional psychological aspects. On the pragmatic level customers’ opinions are collected again to measure satisfaction and to further improve aesthetic appreciation. This brings us back to the space of aesthetic characteristics. The theory explained above is the basis for a computer-oriented design for aesthetics support system. To actually develop such a system, the mapping between the space of design variables (or more specifically, shape variables) and the space of aesthetic characteristics should be formalised. Idealistically the mapping specifies, for an expressed aesthetic intent, those values of shape parameters that realise a design model conform the intention. We have developed a set-theoretic description of such mapping to investigate its feasibility, both from the viewpoint of exploration and of creation, as was depicted in Figure 4. The main ingredients of the formalism are briefly described and a preliminary illustration of its usage is given. The two aforementioned spaces will be referred to as the space S of shape variables and the space A of aesthetic variables, respectively. We provisionally assume that at some point in time, a finite number of shape variables si and aesthetic variables ai are known to be relevant. These variables should be understood to specify each (1) a type and (2) a value domain. We give three examples of possible shape variables: • s1 has type “height” and value domain ℜ +, • s2 has type “angle between arm and body” and value domain {“zero”, “sharp”, “wide”} • s3 has type “y-co-ordinate of the 23d control point” and its value domain is ℜ . A value domain may be either continuous, discrete, ordinal, or nominal. The types are assumed to capture sufficient semantics. As is common in verbal communication, a label such as “height” conveys all necessary information in some context. The proposed formalism, however, has mainly been based on the value domains of the variables. Two examples of aesthetic variables are, • a1 has type “harmony” and value domain {-2, -1, 0, 1, 2}. • a2 has type “emotionality” and value domain {“sad”, “angry”, “joyful”, “serene”}
The mapping f: A → S from aesthetic variables to shape variables has been defined as f(a1,… ,an) = (FS)-1 °FA(a1,… ,an), where FS and FA are auxiliary mappings. FS is a map from S to design space, i.e., it assigns a product design to a given set of values (s1, … , sm). FA is a map from A to design space; it assigns a product design to a given set of values (a1, … , an). A fundamental notion is that any mapping f depends on the existence of (the inverse of) FS and FA. It is thus ensured that a particular relation between shape and aesthetics holds for a particular product design, whereas for a different product design this relation could be different. For example, the introduction of a spike to a product’s shape may cause the design to appear less “calm”. However, if the particular design already contained many evenly distributed spikes, if one spike was missing in the pattern, the inclusion of the spike could make the design more “calm”. To obtain f experimentally, first the mappings FS and FA should be studied. Ultimately, the equation above produces those shape parameter values s1,… sm that realise the intended aesthetic content specified by a1,… ,an. For further details of the theory, we refer to [Van Breemen et al 1998]. To gain detailed insight in the nature of the mapping f, we intend to perform initial experiments using relatively simple spaces S, A and their associated product design spaces. The primary aim will be to test the stability of value assignment to the variables. The depth of the formalism, as illustrated above, may seem distant to every day styling design practice, but is necessary to capture human knowledge, make it tangible, and make it possible for computers to process it. It shows how much effort will be needed to bring the theory and methodology to a pragmatic working system. However, the mathematical work is not the only effort needed. Much attention will have to be paid to issues like user interface, training, changes in company protocols, coherence with existing ways of working, and to obtaining a balanced comprehension of all design aspects. The implications of making those efforts, and where they can lead to will be discussed in the next chapter. 4
IMPLICATIONS AND CONCLUSIONS
Computer implementation of design for aesthetics will involve computer systems that use all possible techniques to quickly input shape representation and facilitates easy manipulation of the shape. As far as the input is concerned, we can foresee systems based on quasi-natural communication, that perform in a smart and reactive way. The system will be able to determine the relevant shape characteristics and assess through knowledge based evaluation of the shape what responses the target customer group is likely to have. An overview must be provided by the system to indicate the severeness of change in the appreciation of the product when changes in shape of the design are suggested. The integration of styling and engineering with the help of computers requires a more natural input and internal representation on that computer. This is even more important when a knowledge system will interact with styling, engineering, and other departments not yet known. This leads to the conclusion that conventional representation is not sufficient. When considering the integration of design for aesthetics in a company environment, we recognise that the system will have its impact on the stylists, but also on the communication with other departments. Major changes will effect the whole company, and need the commitment of the top management to implement cultural changes. Important issues are: • New sources of information, to be used by the styling department, have to be provided by marketing in the design brief, or separately during the process. The information will be used to define and understand the characteristics of the target customers. When this information is available, updates have to be communicated regularly.
• Let everybody in the company see the advantages of tailoring a car design to a niche market. In addition, results of pilot projects will have to show the success and potential revenues the company will experience. • Show that the system supports the tasks human beings are good at, and it does not automate or replace the tasks of the people involved. It enhances their results. • Communication with “engineering and manufacturing” as well as “sales and service” is paramount. The essence of what the process is trying to accomplish must also be communicated to the people making practical sense of the designs, and the people that have to communicate the intents to the right customers. • Education of company staff, in-company and on universities, academies and polytechnicals is of great importance. • Communication with other systems (surface modellers, FEM analysis systems, sales information systems, etc) within the company, but also with suppliers and dealers should be carefully attended to. The mapping of aesthetic characteristics to shape makes it possible to: • assess the appreciation of the appearance of products by target customers • assess the sensitivity of that appreciation to changes in shape • evaluate shape alterations, when interim designs do not yet succeed in evoking intended responses. Maybe even suggestions can be made of what to change when a "more elegant", or "more robust" design is needed. We think that a design for aesthetics support system will have its influences on car model development. It will result in quality through quantity. Much more alternatives can be evaluated, and many more design cycles can be travelled through. This may result in a better high-level overview of consequences, leading to a better “balanced comprehension” of the totality of the product development process. We don’t think designing can be done by computers, but they will be able to process, select, filter and present the information needed and provide an overview of consequences the designers need, to develop new products. The success of product development processes of cars is dependent of a myriad of factors. The return on investment rate will rise when more customers are satisfied with the product they can buy, but the costs of the flexibility need for this must be kept under control. Knowing how to realise appreciation of new designs by controlling the factors a company is able to vary (the shape of a new car) will have its impact. A realistic threat is to rely on the information in the support system without securing / guaranteeing proper updates needed to compensate the time dependency of the information. To further develop the methodology of design for aesthetics, future research has to develop a method to investigate target customers. Resulting information can be used to assess the diversity and structure in their appreciation of the company’s products and those of its competitors. This information will be used to make a specific "mapping function" for a certain target group that will guide stylists to assess the reactions of customers they are not familiar with. This information has to be updated regularly, and is sensitive to time influences caused by changing trends and fashions. The system has to be adaptable to the specific culture of the company, by adapting to the linguistic and graphical language used to denote aesthetic characteristics of the products. ACKNOWLEDGEMENT The research work reported in this paper relates to the Integrated Concept Advancement (ICA) project of the Sub-Faculty of Industrial Design Engineering, FDEP, Delft University of Technology.
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