Franca Giannini

Automatic recognition and representation of shape-based features in a geometric modeling system

Abstract A method is presented for the automatic identification and extraction of feature information from the solid model of an object. The procedure consists in recognizing shape features, extracting these features as solid volumes, and arranging them in a hierarchical structure. This hierarchical model, described in this article, represents the main shape of the object at the highest levels of abstraction and its form features at lower levels of specification. The system is divided into three modules: feature recognition, feature extraction and feature organization. The recognitition step works on a face-based representation of solid objects, called a face adjacency hypergraph and it takes advantage of Kyprianous method (Shape Classification in Computer-Aided-Design, Ph.D. thesis, Computer Laboratory, University of Cambridge, England, July 1980). In the extraction phase each recognized form feature is completed by dummy entities in order to form a feasible object and in the organization step the completed features are arranged into a hierarchical graph, called Structured Face Adjacency Hypergraph.

A modelling tool for the management of product data in a co-design environment

This paper illustrates a product-modelling tool named Product Manager, aimed at supporting networks of small and medium enterprises (SMEs) collaborating in the design of a unique final product. SMEs are usually characterised by well-established knowledge on specific components but, usually, do not have internally all the capacities to develop the complete product and to lead the whole project, so for their nature they adopt co-design principles while maintaining a full autonomy. The presented Product Manager includes all and only those concepts pertaining to the description of the product whose design is in charge of the node and its lower level co-designers. Thus, the emphasis is given to the product specification, possibly by project reuse, and to the negotiation activity usually carried out to identify the right project partner and the final product configuration.

Software environment for CAD/CAE integration

Computer Aided Design (CAD) and Computer Aided Engineering (CAE) are two significantly different disciplines, and hence they require different shape models representations. As a result, models generated by CAD systems are often unsuitable for Finite Element Analysis (FEA) needs. In this paper, a new approach is proposed to reduce the gaps between CAD and CAE softwares. It is based on new shape representation called mixed shape representation. This later, supports simultaneously the B-Rep (manifold and non-manifold) and polyhedral representation, and creates a robust link between the CAD model (B-Rep NURBS) and the polyhedral model. Both representations are maintained on the same topology support called the High Level Topology (HLT), which represents a common requirement for simulation model preparation. A new software environment for CAD/CAE integration based on the mixed representation is presented in this paper, thus a set of necessary tools is associated to the mixed shape representation which contribute to reduce as much as possible the time of model preparation process.

Incorporating free-form features in aesthetic and engineering product design: State-of-the-art report

The use of free-form shapes has become mainstream to design complex products that have to fulfil engineering requirements as well as aesthetic criteria. Even if todays CAD systems can easily represent free-form shapes by means of NURBS surfaces, their definition and modification still require a deep knowledge and a great skill in the manipulation of the underlying mathematical models. The implemented free-form shapes design operators are time consuming and do not enable fast modifications. To overcome these limits, some researches have been undertaken to try to adapt the feature concept, successfully adopted for the design of regular shapes, in the free-form domain. It gives rise to a set of free-form features modelling strategies. This paper gathers together the state-of-the-art of these advances. The various approaches are depicted and compared with respect to a very precise set of criteria expressing the needs in aesthetic and engineering designs. The limits and future trends are presented.

Aesthetic-driven tools for industrial design

The present paper describes an innovative approach in computer-aided industrial design; despite the availability of sophisticated modelling tools, there are still critical issues to be faced in order to provide creative users with functionality really suited to their mentality and able to support them in more easily attaining a model with a certain aesthetic and emotional character and in its preservation during the required model modifications. Currently, the adopted computer-aided design tools offer functionality mostly based on low-level geometric elements, while designers would like to act on properties more directly connected with their design intent. In order to understand which properties are important, we deeply analysed the process followed by designers and computer-aided design operators for achieving the desired product. The possible relationships between shape geometry and aesthetic character have been investigated and a software prototype has been developed to demonstrate the validity of the research outcomes. The presented work has been mainly developed within the framework of a Research and Development project supported by the European Commission, named FIORES-II, which involved, beside several research institutions from different European countries, a wide and direct participation of industrial application companies, such as Alessi, BMW, Pininfarina, Saab, Formtech and Eiger.

AESTHETIC DESIGN OF SHAPES USING FULLY FREE-FORM DEFORMATION FEATURES

Geometric models, such as B-Rep or CSG, are often used as a shared reference representation of the product along the whole design process. However, they do not provide capabilities for conveying complex information related to the involved product development tasks. This also applies for the initial styling activity, in which the shape is described by complex mathematical models handled by tools still not sufficiently suited to the creative designer mentality. To overcome these limits, we introduce the so-called Fully Free-Form Deformation Features (δ–F4) concept and the related manipulation tools. Advantages of both the free-form surface deformation method and the feature-based approach are combined to define these high-level modelling entities enabling the direct shape-oriented modification of surfaces through a restricted set of parameters. They are mainly defined by characteristic curves in order to better cope with the curve-oriented designers’ way of working. In addition, a (δ–F4) classification is proposed to enable a fast access to the desired shape. The proposed approach is illustrated with some examples from our prototype software.Geometric models, such as B-Rep or CSG, are often used as a shared reference representation of the product along the whole design process. However, they do not provide capabilities for conveying complex information related to the involved product development tasks. This also applies for the initial styling activity, in which the shape is described by complex mathematical models handled by tools still not sufficiently suited to the creative designer mentality. To overcome these limits, we introduce the so-called Fully Free-Form Deformation Features (δ–F4) concept and the related manipulation tools. Advantages of both the free-form surface deformation method and the feature-based approach are combined to define these high-level modelling entities enabling the direct shape-oriented modification of surfaces through a restricted set of parameters. They are mainly defined by characteristic curves in order to better cope with the curve-oriented designers’ way of working. In addition, a (δ–F4) classification is p...

A framework for the automatic annotation of car aesthetics

The design of a new car is guided by a set of directives indicating the target market, specific engineering, and aesthetic constraints, which may also include the preservation of the company brand identity or the restyling of products already on the market. When creating a new product, designers usually evaluate other existing products to find sources of inspiration or to possibly reuse successful solutions. In the perspective of an optimized styling workflow, great benefit could be derived from the possibility of easily retrieving the related documentation and existing digital models both from internal and external repositories. In fact, the rapid growth of resources on the Web and the widespread adoption of computer-assisted design tools have made available huge amounts of data, the utilization of which could be improved by using more selective retrieval methods. In particular, the retrieval of aesthetic elements may help designers to create digital models conforming to specific styling properties more efficiently. The aim of our research is the definition of a framework that supports (semi)automatic extraction of semantic data from three-dimensional models and other multimedia data to allow car designers to reuse knowledge and design solutions within the styling department. The first objective is then to capture and structure the explicit and implicit elements contributing to the definition of car aesthetics, which can be realistically tackled through computational models and methods. The second step is the definition of a system architecture that is able to transfer such semantic evaluation through the automatic annotation of car models.

An Ontology-based Framework for Sustainable Factories

ABSTRACTThe problem of factory sustainability is commonly addressed by focusing on specific aspects related to products, processes or production resources, while the impact of the building and facilities is usually neglected even though it counts for 40% of the total worlds energy consumption. This paper presents a holistic framework based on an integrated collaborative virtual environment that facilitates the sharing of the complete factory information and knowledge between various software tools, supporting the sustainable design and management of all the factory entities. In particular, the attention is focused on the Semantic Data Model that provides a semantic representation of the data and knowledge required for sustainability assessment.

A uniform approach to represent features in different application contexts

Abstract A dual description for feature-based modeling is proposed which should be equally efficient for design with feature systems and automatic recognition of instances of standard or user-defined features. This description consists of a primary representation in terms of shape features (neutral description) and a set of viewpoint-dependent feature-based representations (secondary descriptions) which are created by transformations that are viewpoint-specific and which are applied to the shape decomposition model.

Deriving Functionality from 3D Shapes: Ontology Driven Annotation and Retrieval

Abstract3D shapes are of crucial importance in several applications but capturing, representing and processing the complexity of the knowledge a shape may reveal is not an easy task. Therefore it becomes crucial to study which form characteristics may have a specific meaning in order to make explicit, sharable and, above all, machine understandable, the knowledge embedded in 3D shapes. This may be done from different perspectives due to the increasing diversity of potential users. This paper illustrates a knowledge-based (KB) system supporting the functionality driven annotation and retrieval of 3D models. Kernel of the system is the Form, Functionality and Behavior ontology, which provides a representation of the knowledge needed to infer object functionality and behavior from the shape of models and their components.