Proceedings home preface contents authors keywords copyright reference ©2012 Civil-Comp Ltd				Paper 63 Fundamental Research concerning a Three-Dimensional CAD Engine K. Monobe1, S. Kubota2, E. Kitagawa3, K. Nakamura4 and S. Tanaka5 1School of Project Design, Miyagi University, Japan 2Faculty of Software and Information Science, Iwate Prefectural University, Morioka, Japan 3Faculty of Management Information, Hannan University, Osaka, Japan 4Faculty of Information Management, Osaka University of Economics, Japan 5Faculty of Informatics, Kansai University, Osaka, Japan Keywords: three-dimensional computer aided design, three-dimensional data, ISO 10303(STEP). full paper (pdf) - reference The use of three-dimensional data results in improvement in quality, reduction in cost, and an increase in productivity for construction production systems [1,2]. Use in industry is less than desirable because a quality yet affordable three-dimensional CAD engine does not yet exist. A three-dimensional CAD engine must be designed and developed in order to enable low-cost use and rapid implementation, leading to its deployment in various stages of the life cycle of construction projects. In this paper the design of a suitable three-dimensional CAD engine is proposed by investigating the following: situations where three-dimensional CAD is used, growth accompanying three-dimensional CAD packages, standardization trends, existing products, and IT technologies. Based on the results of the investigation, the functional requirements for a three-dimensional CAD engine for the construction industry were determined, and notes regarding the three-dimensional CAD engine design are included. Based on the functional requirements and notes, a design plan for a three-dimensional CAD engine is proposed. Based on the results of the investigation, the functional requirements for a three-dimensional CAD engine for the construction industry were concluded, and a specification for the design of the three-dimensional CAD engine was prepared. First, the required three-dimensional CAD engine functionality was specified. Functions that must be designed include the coordinate system, three-dimensional model display, selection and display techniques for features, three-dimensional modelling, assembly modelling, parametric modelling, attribute information, input and output of files, a viewer for three-dimensional CAD, quality of data preservation, and functions depending on domains. The design of the three-dimensional CAD engine developed during this research was carried out as discussed in the paper. The three-dimensional CAD engine creates three-dimensional models using a method of parametric modelling. Parametric modelling is expressed for the last three-dimensional geometric topology and the restraining conditions (topological restraints), and operation records. In this research, the designer's modelling sequence is recorded as an operation record, and the adopted method incorporates the regeneration of the topology modelling once more. Moreover, a topology can be redefined by changing a parameter and rerunning the operation. This investigation demonstrated the need for the development in accordance with international standards ISO/ STEP, in order to strengthen international competitiveness. By clarifying the positioning of each related ISO/STEP standard, the data model of the three-dimensional CAD engine was investigated. Based on the results of the investigation and notes regarding the three-dimensional CAD engine, a design plan is summarized. In the future, a three-dimensional CAD engine will be developed in accordance with this design plan. References 1 H. Furuta, I. Mikami, T. Usui, M. Hirokane, S. Tanaka, "Trend Research of Electronic Country toward Construction CALS/EC", Sankaido, 2001. 2 Ministry of Land, Infrastructure and Transport, "Ministry of Land, Infrastructure and Transport CALS/EC action program 2008", 2009.