The area of CAD Standardization includes CAD drafting, product data management and exchange,standard part library, Han characters, and standard implementation conformance testing, etc. CAD standardization is one of th...The area of CAD Standardization includes CAD drafting, product data management and exchange,standard part library, Han characters, and standard implementation conformance testing, etc. CAD standardization is one of the key factors to improve CAD development and applications in enterprises.展开更多
There is a CAD （computer-aided design） data exchange format named SXF （scadec exchange format） in the field of Japanese public works which was developed by a consortium in 1999 to be based on the ISO 10303-202, so...There is a CAD （computer-aided design） data exchange format named SXF （scadec exchange format） in the field of Japanese public works which was developed by a consortium in 1999 to be based on the ISO 10303-202, so that the MLIT （Ministry of Land, Infi＇astructure, Transportation and Tourism） could start e-delivery （e-submit） of CAD drawings. It is one of targets for CALS/EC （continuous acquisition and lifecycle support/electric commerce） program which MLIT are promoting since 1999. Most of local governments have followed the MLIT to start e-delivery, so that SXF has become to be a standard in the public works in Japan with many problems. SXF is an exchange format and so many design companies or contractors would submit the CAD drawings with transferred format before the delivery of e-submit even if they use usually another CAD in their offices. This paper will introduce the standard of CAD exchange format SXF through the activities of Japanese public works.展开更多
In this paper,a detailed data list of water plan is given,based on its characteristics.This paper discusses the principles ofestablishing a system of standards for a water plan database,and amethod of modeling the wat...In this paper,a detailed data list of water plan is given,based on its characteristics.This paper discusses the principles ofestablishing a system of standards for a water plan database,and amethod of modeling the water plan data.The information is presentedin a standardization system graph.展开更多
Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline （NURBS） has been used as the de facto standard. In local comer blending, two curves intersecting at that ...Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline （NURBS） has been used as the de facto standard. In local comer blending, two curves intersecting at that comer are first made disjoint, and then the third blending curve is added-in to smoothly join the two curves with G^1- or G^2-continuity. In this paper we present a study to solve the joint problem based on curve extension. The following nice properties of this extension algorithm are exploited in depth： （1） The parameterization of the original shapes does not change; （2） No additional fragments are created. Various examples are presented to demonstrate that our solution is simple and efficient.展开更多
文摘The area of CAD Standardization includes CAD drafting, product data management and exchange,standard part library, Han characters, and standard implementation conformance testing, etc. CAD standardization is one of the key factors to improve CAD development and applications in enterprises.
文摘There is a CAD （computer-aided design） data exchange format named SXF （scadec exchange format） in the field of Japanese public works which was developed by a consortium in 1999 to be based on the ISO 10303-202, so that the MLIT （Ministry of Land, Infi＇astructure, Transportation and Tourism） could start e-delivery （e-submit） of CAD drawings. It is one of targets for CALS/EC （continuous acquisition and lifecycle support/electric commerce） program which MLIT are promoting since 1999. Most of local governments have followed the MLIT to start e-delivery, so that SXF has become to be a standard in the public works in Japan with many problems. SXF is an exchange format and so many design companies or contractors would submit the CAD drawings with transferred format before the delivery of e-submit even if they use usually another CAD in their offices. This paper will introduce the standard of CAD exchange format SXF through the activities of Japanese public works.
文摘In this paper,a detailed data list of water plan is given,based on its characteristics.This paper discusses the principles ofestablishing a system of standards for a water plan database,and amethod of modeling the water plan data.The information is presentedin a standardization system graph.
基金supported by the National Natural Science Foundation of China (Nos. 60603085 and 60736019)the Hi-Tech Research and Development (863) Program of China (No. 2007AA01Z336)Tsinghua Basic Research Foundation, China # Expanded based on "Note on industrial applications of Hu’s surface
文摘Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline （NURBS） has been used as the de facto standard. In local comer blending, two curves intersecting at that comer are first made disjoint, and then the third blending curve is added-in to smoothly join the two curves with G^1- or G^2-continuity. In this paper we present a study to solve the joint problem based on curve extension. The following nice properties of this extension algorithm are exploited in depth： （1） The parameterization of the original shapes does not change; （2） No additional fragments are created. Various examples are presented to demonstrate that our solution is simple and efficient.
