Structured Modeling For Aesthetic Design Chiara Eva Catalano * Maria Meirana * Laura Papaleo * Istituto per la Matematica Applicata - Consiglio Nazionale delle Ricerche * {chiara, meirana, papaleo}@ima.ge.cnr.it Abstract Nowadays, it is very common that the same company produces the mechanical and electrical parts of a product also for competitor trademarks. The differences in products are mainly given by shape details and then the choice of the customer results strongly affected by aesthetic aspects (color, shape, and so on). These ones are not so conditioned by technology as in the past because of the availability of new materials and tools, able to render very complex shapes and to provide a greater freedom to the stylist creativity. In this paper, the introduction and the study of high-level modeling entities is attained. From the one hand, these elements would improve the CAS design, bringing the computer way of operating nearer to the stylist way of thinking. The analysis focalizes on possible shape modification techniques, which take into account the emotional impact. From the other hand, the adoption of the feature- based concept is introduced for allowing the reuse of already existing models for obtaining new, but aesthetically similar, products. Keywords: styling, structural features, detail features, similarity, emotion. 1 Introduction In a very competitive world wide market, where product life time is shorter and shorter, the aesthetic aspect is one of the most important key elements for the success of a product. To this aim, new Computer-Aided Design (CAD) and Styling (CAS) tools have been developed. They are trying to support the styling activity providing high quality rendering and animation facilities. This leads to an efficient simulation and evaluation of a product in a computer, reducing the number of physical prototypes necessary for the final product specification. Unfortunately, even if the market offers many similar products, these systems do not support the fast generation of shape alternatives starting from already existing models. Changing a small detail is sometimes really difficult, also because, today, the modeling activity is based on low-level geometric elements. In this sense, high-level entities, which encapsulate more than the pure geometry of the created object, have to be introduced. The concept of feature seems to be the key for associating specific aesthetic and functional meaning to groups of geometric elements, offering the advantage of treating them as single entities. For this reason, two typologies of features are introduced in this paper. From the one hand, the structural features, which represent the skeleton of the model, also involving emotional characteristics; from the other one, the detail features, which complete the model adding local elements. The feature-based modeling approach has two main advantages: it becomes closer to the way of operating of the stylist and allows the reuse of models for creating new ones. The last point let the designers retrieve similar (according to their ideas) objects, in order to modify them and to obtain the desired result. The definition of surface modification techniques by features is a crucial aspect to study; in particular structural features need modification methods which take into account the emotional characteristics of the active model, while the detail ones require creation and modification processes that use high-level parameters. The research scenario is exemplified in Figure 1. Designer CAS/CAD design (feature-based approach) Aesthetic Evaluation Structural feature modification Detail feature modification Figure 1 - The research scenario The paper is organized as follows. In the second chapter the styling activity is summarized in the essential phases. Chapter 3 introduces the general concept of feature in product design, and in 4, structural and detail features are analyzed. In the end, the fifth chapter deals with the modification of an object by means of the defined features.