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, the author presents a class of stationary ternary 4-point approximating symmetrical subdivision algorithm that reproduces cubic polynomials. By these subdivision algorithms at each refinement step, new ...In this paper, the author presents a class of stationary ternary 4-point approximating symmetrical subdivision algorithm that reproduces cubic polynomials. By these subdivision algorithms at each refinement step, new insertion control points on a finer grid are computed by weighted sums of already existing control points. In the limit of the recursive process, data is defined on a dense set of point, The objective is to find an improved subdivision approximating algorithm which has a smaller support and a higher approximating order. The author chooses a ternary scheme because the best way to get a smaller support is to pass from the binary to ternary or complex algorithm and uses polynomial reproducing propriety to get higher approximation order. Using the cardinal Lagrange polynomials the author has proposed a 4-point approximating ternary subdivision algorithm and found that a higher regularity of limit function does not guarantee a higher approximating order. The proposed 4-point ternary approximation subdivision family algorithms with the mask a have the limit function in C2 and have approximation order 4. Also the author has demonstrated that in this class there is no algorithm whose limit function is in C3. It can be seen that this stationary ternary 4-point approximating symmetrical subdivision algorithm has a lower computational cost than the 6-point binary approximation subdivision algorithm for a greater range of points.展开更多
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, the author presents a class of stationary ternary 4-point approximating symmetrical subdivision algorithm that reproduces cubic polynomials. By these subdivision algorithms at each refinement step, new insertion control points on a finer grid are computed by weighted sums of already existing control points. In the limit of the recursive process, data is defined on a dense set of point, The objective is to find an improved subdivision approximating algorithm which has a smaller support and a higher approximating order. The author chooses a ternary scheme because the best way to get a smaller support is to pass from the binary to ternary or complex algorithm and uses polynomial reproducing propriety to get higher approximation order. Using the cardinal Lagrange polynomials the author has proposed a 4-point approximating ternary subdivision algorithm and found that a higher regularity of limit function does not guarantee a higher approximating order. The proposed 4-point ternary approximation subdivision family algorithms with the mask a have the limit function in C2 and have approximation order 4. Also the author has demonstrated that in this class there is no algorithm whose limit function is in C3. It can be seen that this stationary ternary 4-point approximating symmetrical subdivision algorithm has a lower computational cost than the 6-point binary approximation subdivision algorithm for a greater range of points.
