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Grammar representations to facilitate style innovation
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Grammar representations to facilitate style innovation

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presentation at eCAADe 2006, 6-8 sep 2006, Volos, Greece …

presentation at eCAADe 2006, 6-8 sep 2006, Volos, Greece

Previous research in generative design has suggested that shape grammar transformations could be used for developing new design styles by the systematic modification of grammars that encode existing styles. Our research explores how such grammar transformations can be facilitated to be responsive to changes in design style requirements. For this it is important to consider the structure and organization of rules, as well as the description of the styles of designs generated by a grammar. Using an example of mobile phone design, we outline the development of a flexible grammar structure that is conducive to transformations. The grammar is augmented with a style description scheme based on the concept of semantic differential to map the style characteristics of grammar components. These measures could be significant for driving purposeful grammar transformations for style adaptation and innovation.

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  • Abstract. Previous research in generative design has suggested that shape grammar transformations could be used for developing new design styles by the systematic modification of grammars that encode existing styles. Our research explores how such grammar transformations can be facilitated to be responsive to changes in design style requirements. For this it is important to consider the structure and organization of rules, as well as the description of the styles of designs generated by a grammar. Using an example of mobile phone design, we outline the development of a flexible grammar structure that is conducive to transformations. The grammar is augmented with a style description scheme based on the concept of semantic differential to map the style characteristics of grammar components. These measures could be significant for driving purposeful grammar transformations for style adaptation and innovation. Keywords. Design grammars; style; product design; generative design
  • Introduction Grammar transformations for style synthesis Method overview Discussion Presentation Outline Ongoing research in grammar transformations for the development of new styles of design based on previous ones. Introduction The notion of style is of special relevance in contemporary design and architecture due to its relationship with identity and image making, as it signifies a distinct design language unique to a particular architect, place or source, with specific characteristics that distinguish it from other designs. It has been a common practice in design fields such as architecture to develop new design styles by adapting previous ones. In particular, product design domains such as those of mobile phone design and automobile design require frequent and periodic changes in design style in order to meet market competition. For the sake of consistency in product image, it is often a vital design objective that new design styles are based on previous ones. Thus, improvement on existing designs and design styles is regarded as a significant strategy of design innovation in product design (Baxter, 1995). Such needs of style adaptation and innovation may be addressed by making use of the method of grammar transformations, which allow the adaptive reuse of previous design styles encoded by grammar rules (Knight, 1994). Grammar transformations are also significant since they make possible the use of grammars beyond a single application. The objective of our research is to explore how such grammar transformations may be facilitated as a response to changes in design style objectives and criteria.
  • Grammar transformations for style synthesis Shape grammars provide a generative construct for encoding design styles. Previous work in using shape grammars for capturing design styles encompasses domains of architecture, engineering and product design (McCormack et al., 2004). Knight developed a formal model for grammar transformation that made use of rule addition, deletion or modification based on changes in grammar primitives and spatial relations. One of the primary advantages of the grammar transformation model is that it makes possible the reuse of design information in extant grammars for the generation of new design languages. Grammar transformations have thus been used to analyze relationships between various styles of design (Knight, 1994) and to adapt preexisting styles of designs into new ones (Colakoglu, 2005). Although previous works recognize the utility of grammar transformation for the reuse of design style information, they do not give an explicit description of the rationale for transformations (Chase and Liew, 2001) and do not provide mechanisms for the comparison and evaluation of design styles generated by various grammars. This work seeks to address such issues by developing a flexible grammar structure by organizing grammar rules; and to develop a method to represent the styles generated by grammars. The role of the former is to assist designers in authoring grammars that are conducive to transformations, while the latter would allow designers to interpret and compare styles generated by various grammars.
  • Style construct is especially important in the domain of product design, since it is understood as the distinct design language unique to a particular brand, with specific characteristics that help in establishing a unique product identity and help in fostering brand recognition. Product design domains such as those of mobile phones and automobiles require frequent and peri­odic changes in design style in order to meet market competition. For the sake of consistency in product image, it is often a vital design objective that new design styles are based on previous ones. Thus, improvement on exist­ing designs and design styles is regarded as a significant strategy of design innovation in product design (Baxter 1995).
  • Style construct is especially important in the domain of product design, since it is understood as the distinct design language unique to a particular brand, with specific characteristics that help in establishing a unique product identity and help in fostering brand recognition. Product design domains such as those of mobile phones and automobiles require frequent and peri­odic changes in design style in order to meet market competition. For the sake of consistency in product image, it is often a vital design objective that new design styles are based on previous ones. Thus, improvement on exist­ing designs and design styles is regarded as a significant strategy of design innovation in product design (Baxter 1995). Style may be a specific view/ perspective of a design language…..
  • Methods of describing the style or styles generated by a grammar have to date not been considered in the shape grammar literature . However, a thorough description of style requires a study of form ele­ments and their composition, as well as its content (Ackerman 1963). The latter involves the representation and evaluation of style qualities such as balance, harmony and beauty. Although grammars encapsulate design styles through the description of visual elements and their organization, description of style qualities has not been examined in the shape grammar literature. Existing works assume such style qualities to be implicit in grammar components, and interpret the design style of a grammar through the design language generated by it. Often design grammars tend to be quite lengthy with a great number of rules, and for such grammars, the aforementioned approach to understand a grammar’s style may be a very tedious process. Furthermore, this approach poses problems for style adaptation by grammar transformation methods, as it does not adequately describe the style charac­teristics of the design language generated by the grammar under study.
  • Style is a notion used to classify a set of objects, based on given criteria such as time period, geographic region, features, culture or traditions. Objects in a particular style share features and their organization. In art and design, style is used as an ordering principle that describes commonalties underlying a set of artefacts. The definition of style can be viewed from two perspectives: In design practice, designs rarely start from scratch. Designs are more often than not based on precedents, or on the designer’s accumulated experience. Often architects choose to take inspiration from historic styles of design or from the styles of well-known architects. Many a time design problems are of a nature that requires the solution to be developed in a particular design style. In such situations, the designer uses interpretive methods to adapt such well-known styles to changes in design criteria or context, according to their own artistic perception. Thus, new design languages emerge from the transformation of previous design languages.
  • Formal rule systems based on strong syntax. Analogous to natural languages Invented by Stiny & Gips in 1970s, shape grammars have been used to study various realms of design. Grammars are both prescriptive and descriptive: the rules of a grammar generate designs but can also be considered descriptions of the forms of the designs
  • Based on the style description scheme, a number of measures may be developed to define various perspectives of style. Method Overview This study views design style from the perspective of the design product that is, as a vocabulary of formal elements composed by a syntax (Ackerman, 1963). Stylistic change may thus be understood as changes in a style’s constituent design elements and their interrelationships. We make use of an example of mobile phone designs. A grammar is authored by translating key design elements into shapes and their interrelationships into spatial relations. A standard format is developed for representing grammar rules. Sub-designs in grammar rules are expressed as instances of shapes linked to each other through instances of spatial relations, thus giving an explicit description of their style constituents (Figure 1). This concept is similar to previous works that propose the separation of ‘element’ and ‘structure’ in designs (Carlson and Woodbury, 1992). This facilitates style exploration by rule modification based on changes in either shapes or spatial relationships. The organization of rules is critical for their retrieval and adaptation in rule based systems (Seebohm and Wallace, 1998). Hence, grammar rules are decomposed into their most basic form and are organized in a hierarchy, differentiating sub-rules and their variations in distinct function based sets. This makes possible the addition, deletion or replacement of rules at various levels of complexity. Furthermore, such an organization gives a modular nature to the grammar making possible transformation by replacement of given rule sets with other sets that achieve the same functional objective. State change controls and object constraints controls play an important part here in ensuring syntactically correct designs upon grammar transformation. In order to facilitate transformations, it is also important to consider the interdependencies in grammar components, as modification of one rule may affect other rules and leave them obsolete. In order to address this, a rule dependency graph is used (Figure 2). Such a graph elucidates the relationships between grammar rules, and informs designers of the branch or branches of dependent grammar rules that might need to be transformed if a given rule is changed. This helps in preventing redundancy in rules when the grammar is transformed. The second part of our work deals with the development of a description scheme (Stiny, 1981) to describe the style or styles generated by a grammar by mapping the style characteristics of grammar components. We make use of the method of the semantic differential which has been used to characterize styles in product design (Chen and Owen, 1997). The style description scheme comprises of a set of style attributes that are linked to every grammar component. A set of opposing adjectival pairs are selected for the description of these style attributes for each grammar component (Table 1). These are quantified by incorporating user defined values on a numeric scale of -5 to 5, and the data generated is then analyzed. We are looking at a number of analytical measures, one of which is described here. We define the style generated by a grammar as a range within which a number of design styles might be interpreted. The style range of a grammar is represented by mapping the maximum and the minimum attribute values of grammar components. Figure 3 shows the style range generated by the mobile phone grammar. Such a method of mapping the style attributes of grammar components could be used to assist designers in assembling grammars in selecting appropriate shapes, spatial relations and rules that have desired characteristics. It could also be used to guide grammar transformations by making strategic changes to specific grammar components.
  • We augment our design grammar with a style description scheme, which is a set of style attributes associated with every grammar component. A set of opposing adjectival pairs are selected for the description of these style attributes for each grammar component (Table 1). These may be quantified by incorporating user defined values on a numeric scale of -5 to 5. The description scheme is represented in conjunction with the grammar rules. Sub-designs are represented as explicit associations between shapes and spatial relations. For ease of purpose, assemblies of shapes are represented as enti­ties called ‘shape groups’. Examples of rules and their associated descriptions are shown in Figure 1.
  • First, we define the style generated by a grammar as a range within which a number of design styles might be interpreted. The style range of a grammar is represented by mapping the maximum and the minimum attribute values of grammar components. All the designs generated by a grammar would have style descriptions that fall within this range. Figure 2(a) shows the style range generated by the mobile phone grammar. Second, we map average values of style attributes of grammar components. This measure depicts the most likely style description of the designs to be generated by the grammar (Figure 2b).
  • Third, we map the percentage of rules that have particular style characteristics. This would indicate to the designer the inclination of the grammar towards particular style characteristics. Figure 3 shows this measure for the mobile phone grammar. It can be seen from the chart that all rules of the grammar have symmetrical and axial relationships.
  • Third, we map the percentage of rules that have particular style characteristics. This would indicate to the designer the inclination of the grammar towards particular style characteristics. Figure 3 shows this measure for the mobile phone grammar. It can be seen from the chart that all rules of the grammar have symmetrical and axial relationships.
  • The objective of the work is to develop goal based grammar transformations for the purpose of systematic stylistic change and style innovation. The method of addressing this is by developing a style description scheme for grammar components. We’re exploring the use of empirical methods for establishing quantitative values to style descriptors. The method might be more useful for large grammars, which might have a number of related styles resident in their design languages. Experiment: Project work with students Provide students with shapes, spatial relations, rules with description scheme. Ask students to assemble grammar based on a particular style brief. Ask students to make transformations in grammar, based on changes in style brief. Elicit feedback from students.
  • A number of previous works have focused on describing the style of products and design artefacts. We believe, however, that this is the first attempt to describe the style or styles generated by a grammar. Although the example shown here is limited in its scope of style description and semantics, it seems plausible that the method could be extended to describe style knowledge of greater complexity. --the method captures a perspective of style in a given set of objects. ---assisting designers in assembling grammars with particular style or brand characteristics…. Discussion In this paper we outlined the development of a flexible grammar structure for the purpose of facilitating grammar transformation by organization of rules into modular function based rule sets. Furthermore, we proposed the development of a style description scheme for a pertinent description of the style or styles generated by a design grammar. The grammar representation method as described here facilitates grammar transformations based on addition, deletion and modifications in shapes and spatial relations, and allows replacement of rule sets without leaving parts of the grammar obsolete. Furthermore, the development of the style description scheme makes possible evaluation and comparison of styles generated by various grammars. In a style reuse scenario, the comparison of the new or altered style brief with the style range generated by the existing grammar could prompt goal directed transformations to the grammar for the development of styles of design that correspond to the altered brief. Such a method could particularly be of use in the domain of product design, where design style criteria are continually undergoing change for the same product. This work is based on the designer’s interpretation and thus the style description method as described here would include the designer’s bias. We aim to explore the use of empirical methods and mathematical measures to quantify style characteristics of grammar components. We also aim to make use of weighting mechanisms in order to account for dominant style characteristics. Grammar structuring as described here facilitates transformations that essentially have the same form-function decomposition. We acknowledge that in order to allow a creative exploration of style, the representation should make possible the recognition of alternative groupings of design components as well as their emergent properties. These are relevant issues that are directions for further research.
  • Transcript

    • 1. Grammar representationsto facilitate style innovation Sumbul Ahmad Scott Chase eCAADe 2006 Department of Architecture
    • 2.  Aim strategic grammar transformations Background style description in grammars Method example of mobile phone grammar Summary & further work Presentation outline
    • 3.  Formal method to make structured changes in design morphology Allow generation of new design languages based on previous ones Transformation in De Stijl paintings (Knight)Introduction: Grammar transformations
    • 4. To develop a method for strategic grammartransformations for the purpose of style synthesis Changes Transform Adapted Style brief Grammar DesignsAims: Goal-oriented transformations
    • 5.  How to define and represent the style generated by a grammar? How to compare/ evaluate the style generated by a transformed grammar with the original grammar? Description of ‘content’ of style is implicit in existing shape grammar literatureAims: Issues
    • 6. Rules DesignsAims: Style description in grammars
    • 7. Product View Process ViewSources Meyer Schapiro, J.S. Ackerman Herbert SimonDefinition Style as the common features Style as a ‘way of doing things’ present in a set of design artefactsDescription Form (Elements & relationships) Description of processes that Content (meaning, qualities) generate designsBackground: Defining style of artefacts
    • 8. Shapes, Spatial Shape Language of composed Shape Relations grammar designs of Rules geometric elements Style KnowledgeComponents of a grammar Rule 1 Rule 3 Rule 4 Rule 1 Rule 1 Rule 4 Sequence of rule application Background: How grammars encode style
    • 9. Use of semantic differential to quantify style attributesassociated with grammar components Primitives Style Characteristics Spatial Relations Style Characteristics Rules Grammar Style Description SchemeMethod: Style Description Scheme
    • 10.  Developing style descriptors, and associating them with grammar components Quantifying these on a scale of -5 to 5 Grammar Component Adjectival pair Shape Boundary A1 Rectilinear Curvilinear A2 Basic Derivative Corners A3 Angular Rounded Spatial Relationship Organisation B1 Axial Non-axial B2 Symmetrical Asymmetrical B3 Monolithic Fragmentary B4 Directional Stable Shape group Arrangement C1 Rectlinear Curvilinear C2 Symmetrical Assymetrical C3 Monolithic Fragmentary C4 Directional StableMethod: Mobile Phone Grammar
    • 11. Shape 1 Shape 2 Shape (Average) Spatial Relation Shape Group A1 A2 A3 A1 A2 A3 A1 A2 A3 B1 B2 B3 B4 C1 C2 C3 C4 Symmetrical--Asymmetrical Symmetrical--Asymmetrical Monolitithic--Fragmentary Monolitithic--Fragmentary Rectilinear--Curvilinear Rectilinear--Curvilinear Rectilinear--Curvilinear Rectilinear--CurvilinearAnalysing Angular--Rounded Angular--Rounded Angular--Rounded Directional--Static Directional--Static Basic--Derivative Basic--Derivative Basic--Derivative Axial--Non-axial data Rule 1 -4 -4 3 -4 -4 3 Rule 2a -4 -4 3 3 2 1 -1 -1 2 -5 -4 -4 4 Rule 2b -4 -4 3 -4 -4 3 -4 -4 3 -5 -5 -5 5 Rule 3a -4 -4 3 -4 -4 3 -5 -5 -2 4 5 2 -3 -3 Rule 3b -4 -4 3 -4 -4 3 -5 -5 -2 4 5 2 -3 -3 Rule 3c -4 -4 3 -4 -4 3 -5 -5 -2 4 -3 2 4 -3 Rule 4a -4 -3 -4 -4 Rule 4b -4 -2 3 -4 Rule 5.1a -5 -5 4 4 -4 -4 -3 4 Rule 5.2a -5 -5 4 4 -4 -4 -3 4 Rule 5.2b -5 -5 4 4 -4 -4 -3 4 Rule 6.1a -4 -4 4 -4 -4 4 Rule 6.2a -4 -4 4 -4 -4 4 Rule 7.1a -5 -5 4 4 -4 -4 -3 4 Rule 7.2a -5 -5 4 4 -4 -4 -3 4 Rule 8.1a -4 -4 4 -4 -4 4 Rule 8.2a -4 -4 4 -4 -4 4 Rule 8.3a -4 4 3 -4 4 3 Rule 8.3b 4 -4 3 4 -4 3 Rule 8.3c 4 -4 3 4 -4 3 Rule 9a -5 -5 -5 -5 -5 -5 Rule 9b -3 4 -5 -3 4 -5 Rule 10aMethod: Measures to describe style
    • 12.  A number of styles may be interpreted in the design language generated by a grammar Developing ‘style range’ for a grammarMethod: Measures to describe style
    • 13. 100% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% Curvilinear Rectilinear A1 Derivative A2 Basic Shapes Angular Rounded A3 Axial B1 Symmetrical B2 Inclination of grammar Monolithic Fragmentary B3 Spatial Relations Directional Static B4Method: Measures to describe style Rectilinear Curvilinear C1 Symmetrical Asymmetrical C2 Fragmentary towards particular style characteristics Monolithic C3 Shape Groups Directional Static C4
    • 14.  Developing a flexible grammar structure Explicit representation of shapes & spatial relations Rule organization, dependencies in rule setsMethod: Grammar Representation
    • 15. Project work with students – Provide students with shapes, spatial relations, rules with description scheme – Students assemble grammar based on a particular style brief – Students make transformations in grammar, based on changes in style brief – FeedbackExperiments: Goal based grammar transformations
    • 16. Explicit description of style/s generated by a grammarby mapping style characteristics of grammarcomponents using the semantic differential methodApplications Assisting designers in assembling grammars Structured transformations for style synthesis Aesthetic evaluation of grammarsAdditional issues Description of emergent style attributes Exploring multiple levels of representation Exploring higher level semanticsSummary