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CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
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_id	avocaad_2001_22
id	avocaad_2001_22
authors	Jos van Leeuwen, Joran Jessurun
year	2001
title	XML for Flexibility an Extensibility of Design Information Models
source	AVOCAAD - ADDED VALUE OF COMPUTER AIDED ARCHITECTURAL DESIGN, Nys Koenraad, Provoost Tom, Verbeke Johan, Verleye Johan (Eds.), (2001) Hogeschool voor Wetenschap en Kunst - Departement Architectuur Sint-Lucas, Campus Brussel, ISBN 80-76101-05-1
summary	The VR-DIS research programme aims at the development of a Virtual Reality – Design Information System. This is a design and decision support system for collaborative design that provides a VR interface for the interaction with both the geometric representation of a design and the non-geometric information concerning the design throughout the design process. The major part of the research programme focuses on early stages of design. The programme is carried out by a large number of researchers from a variety of disciplines in the domain of construction and architecture, including architectural design, building physics, structural design, construction management, etc.Management of design information is at the core of this design and decision support system. Much effort in the development of the system has been and still is dedicated to the underlying theory for information management and its implementation in an Application Programming Interface (API) that the various modules of the system use. The theory is based on a so-called Feature-based modelling approach and is described in the PhD thesis by [first author, 1999] and in [first author et al., 2000a]. This information modelling approach provides three major capabilities: (1) it allows for extensibility of conceptual schemas, which is used to enable a designer to define new typologies to model with; (2) it supports sharing of conceptual schemas, called type-libraries; and (3) it provides a high level of flexibility that offers the designer the opportunity to easily reuse design information and to model information constructs that are not foreseen in any existing typologies. The latter aspect involves the capability to expand information entities in a model with relationships and properties that are not typologically defined but applicable to a particular design situation only; this helps the designer to represent the actual design concepts more accurately.The functional design of the information modelling system is based on a three-layered framework. In the bottom layer, the actual design data is stored in so-called Feature Instances. The middle layer defines the typologies of these instances in so-called Feature Types. The top layer is called the meta-layer because it provides the class definitions for both the Types layer and the Instances layer; both Feature Types and Feature Instances are objects of the classes defined in the top layer. This top layer ensures that types can be defined on the fly and that instances can be created from these types, as well as expanded with non-typological properties and relationships while still conforming to the information structures laid out in the meta-layer.The VR-DIS system consists of a growing number of modules for different kinds of functionality in relation with the design task. These modules access the design information through the API that implements the meta-layer of the framework. This API has previously been implemented using an Object-Oriented Database (OODB), but this implementation had a number of disadvantages. The dependency of the OODB, a commercial software library, was considered the most problematic. Not only are licenses of the OODB library rather expensive, also the fact that this library is not common technology that can easily be shared among a wide range of applications, including existing applications, reduces its suitability for a system with the aforementioned specifications. In addition, the OODB approach required a relatively large effort to implement the desired functionality. It lacked adequate support to generate unique identifications for worldwide information sources that were understandable for human interpretation. This strongly limited the capabilities of the system to share conceptual schemas.The approach that is currently being implemented for the core of the VR-DIS system is based on eXtensible Markup Language (XML). Rather than implementing the meta-layer of the framework into classes of Feature Types and Feature Instances, this level of meta-definitions is provided in a document type definition (DTD). The DTD is complemented with a set of rules that are implemented into a parser API, based on the Document Object Model (DOM). The advantages of the XML approach for the modelling framework are immediate. Type-libraries distributed through Internet are now supported through the mechanisms of namespaces and XLink. The implementation of the API is no longer dependent of a particular database system. This provides much more flexibility in the implementation of the various modules of the VR-DIS system. Being based on the (supposed to become) standard of XML the implementation is much more versatile in its future usage, specifically in a distributed, Internet-based environment.These immediate advantages of the XML approach opened the door to a wide range of applications that are and will be developed on top of the VR-DIS core. Examples of these are the VR-based 3D sketching module [VR-DIS ref., 2000]; the VR-based information-modelling tool that allows the management and manipulation of information models for design in a VR environment [VR-DIS ref., 2000]; and a design-knowledge capturing module that is now under development [first author et al., 2000a and 2000b]. The latter module aims to assist the designer in the recognition and utilisation of existing and new typologies in a design situation. The replacement of the OODB implementation of the API by the XML implementation enables these modules to use distributed Feature databases through Internet, without many changes to their own code, and without the loss of the flexibility and extensibility of conceptual schemas that are implemented as part of the API. Research in the near future will result in Internet-based applications that support designers in the utilisation of distributed libraries of product-information, design-knowledge, case-bases, etc.The paper roughly follows the outline of the abstract, starting with an introduction to the VR-DIS project, its objectives, and the developed theory of the Feature-modelling framework that forms the core of it. It briefly discusses the necessity of schema evolution, flexibility and extensibility of conceptual schemas, and how these capabilities have been addressed in the framework. The major part of the paper describes how the previously mentioned aspects of the framework are implemented in the XML-based approach, providing details on the so-called meta-layer, its definition in the DTD, and the parser rules that complement it. The impact of the XML approach on the functionality of the VR-DIS modules and the system as a whole is demonstrated by a discussion of these modules and scenarios of their usage for design tasks. The paper is concluded with an overview of future work on the sharing of Internet-based design information and design knowledge.
series	AVOCAAD
email
last changed	2005/09/09 10:48

_id	ddss2004_d-49
id	ddss2004_d-49
authors	Polidori, M. and R. Krafta
year	2004
title	Environment – Urban Interface within Urban Growth
source	Van Leeuwen, J.P. and H.J.P. Timmermans (eds.) Developments in Design & Decision Support Systems in Architecture and Urban Planning, Eindhoven: Eindhoven University of Technology, ISBN 90-6814-155-4, p. 49-62
summary	This work presents the synthesis of a model of urban growth dedicated to accomplish simulations of urban spatial dynamics, based on integrated urban and environmental factors and promoting simultaneity among external and internal growth. The city and surrounding environment are captured and modeled in computational ambient, by application of the centrality / potential model (Krafta, 1994 and 1999), with support of graph theory, cellular automata, GIS and geocomputation. The model assumes the city as a field of opportunities for obtaining income, mediated by the space, which is composed of urban and environmental attributes, that work as attractors or as resistances for the urban growth. The space configuration and the distribution of those attributes generate tensions that differentiate qualitatively and quantitatively the space, through the centrality measure (built with the support of graphs techniques), coming to provoke growth in places with larger potential of development (built with the help of techniques of CA – cellular automata). Growths above environmental thresholds are considered problems, generated and overcome in the same process of production of the urban space. Iterations of that process offer a dynamic behaviour to the model, allowing to observe the growth process along the time. The model presents several possibilities: a) urban - natural environment integration; b) internal and external growth integration; c) variety in the scale; d) GIS integration and geocomputation; e) user interface; f) calibration; g) theoretical possibilities; and h) practical possibilities.
keywords	Environment, Urban Growth, Urban Morphology, Simulation
series	DDSS
last changed	2004/07/03 22:13

_id	44c0
authors	Van Leeuwen, Jos P.
year	1999
title	Modelling architectural design information by features : an approach to dynamic product modelling for application in architectural design
source	Eindhoven University of Technology
summary	Architectural design, like many other human activities, benefits more and more from the ongoing development of information and communication technologies. The traditional paper documents for the representation and communication of design are now replaced by digital media. CAD systems have replaced the drawing board and knowledge systems are used to integrate expert knowledge in the design process. Product modelling is one of the most promising approaches in the developments of the last two decades, aiming in the architectural context at the representation and communication of the information related to a building in all its aspects and during its complete life-cycle. However, after studying both the characteristics of the product modelling approach and the characteristics of architectural design, it is concluded in this research project that product modelling does not suffice for support of architectural design. Architectural design is characterised mainly as a problem solving process, involving illdefined problems that require a very dynamic way of dealing with information that concerns both the problem and emerging solutions. Furthermore, architectural design is in many ways an evolutionary process. In short term this is because of the incremental approach to problem solving in design projects; and in long term because of the stylistic development of designers and the continuous developments in the building and construction industry in general. The requirements that are posed by architectural design are concentrated in the keywords extensibility and flexibility of the design informationmodels. Extensibility means that designers can extend conceptual models with definitions that best suit the design concepts they wish to utilise. Flexibility means that information in design models can be structured in a way that accurately represents the design rationale. This includes the modelling of incidental characteristics and relationships of the entities in the model that are not necessarily predefined in a conceptual model. In general, product modelling does not adequately support this dynamic nature of design. Therefore, this research project has studied the concepts developed in the technology of Feature-based modelling, which originates from the area of mechanical engineering. These concepts include the usage of Features as the primitives for defining and reasoning about a product. Features have an autonomous function in the information model, which, as a result, constitutes a flexible network of relationships between Features that are established during the design process. The definition of Features can be specified by designers to formalise new design concepts. This allows the design tools to be adapted to the specific needs of the individual designer, enlarging the library of available resources for design. In addition to these key-concepts in Feature-based modelling as it is developed in the mechanical engineering context, the project has determined the following principles for a Feature-based approach in the architectural context. Features in mechanical engineering are used mainly to describe the lowest level of detail in a product's design, namely the characteristics of its parts. In architecture the design process does not normally follow a strictly hierarchical approach and therefore requires that the building be modelled as a whole. This implies that multiple levels of abstraction are modelled and that Features are used to describe information at the various abstraction levels. Furthermore, architectural design involves concepts that are non-physical as well as physical; Features are to be used for modelling both kinds. The term Feature is defined in this research project to reflect the above key-concepts for this modelling approach. A Feature is an autonomous, coherent collection of information, with semantic meaning to a designer and possibly emerging during design, that is defined to formalise a design concept at any level of abstraction, either physical or non-physical, as part of a building model. Feature models are built up entirely of Features and are structured in the form of a directed graph. The nodes in the graph are the Features, whereas the arcs are the relationships between the Features. Features can be of user-defined types and incidental relationships can be added that are not defined at the typological level. An inventory in this project of what kind of information is involved in the practice of modelling architectural design is based on the analysis of a selection of sources of architectural design information. This inventory is deepened by a case study and results in the proposition of a categorisation of architectural Feature types.
keywords	Automated Management Information Systems; Computer Aided Architectural Design; Information Systems; Modelling
series	thesis:PhD
email
more	http://www.ds.arch.tue.nl/jos/thesis/
last changed	2003/02/12 22:37

_id	6d88
authors	Achten, Henri H. and Van Leeuwen, Jos P.
year	1999
title	Feature-Based High Level Design Tools - A Classification
source	Proceedings of the Eighth International Conference on Computer Aided Architectural Design Futures [ISBN 0-7923-8536-5] Atlanta, 7-8 June 1999, pp. 275-290
summary	The VR-DIS project aims to provide design support in the early design stage using a Virtual Reality environment. The initial brief of the design system is based on an analysis of a design case. The paper describes the process of analysis and extraction of design knowledge and design concepts in terms of Features. It is demonstrated how the analysis has lead to a classification of design concepts. This classification forms one of the main specifications for the VR-based design aid system that is being developed in the VR-DIS programme. The paper concludes by discussing the particular approach used in the case analysis and discusses future work in the VR-DIS research programme.
keywords	Features, Feature-Based modelling, Architectural Design, Design Process, Design Support
series	CAAD Futures
email
last changed	2006/11/07 07:22

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