3 results
Search Results
Now showing 1 - 3 of 3
Item A Geometric Data Manager(The Eurographics Association, 1983) Tikkanen, M.; Mantyla, M.; Tamminen, M.; P.J.W. ten HagenGWB/DMS is the data management subsystem of GWB, the Geometric Work-Bench. I t has been designed specifically for three-dimensional computeraided design applications. As the data definition and manipulation take place with extensions of high-level language constructs, GWB/DMS offers a direct migration from an independent "in-core" application to one using a database. Besides, the user can define additional access paths using geometric or conventional indices. The interactive nature of design is taken into account by including a simple transaction control mechanism. Transparency in ordinary programming and efficiency are the main design criteria of GWB/DMS. Its novelties are: 1) geometric indices facilitating access by location, 2) address calculation as the main access method and 3) tools for controlling the "physical closeness" of database objects.Item Solid Modeling with Parametric Surfaces(The Eurographics Association, 1983) Alander, J.; Mantyla, M.; RANTANEN, T.; P.J.W. ten HagenSolid modeling systems are now entering industrial usage. To guarantee their wide applicability, the capabilities of solid modelers should be enhanced to allow inclusion of free-form surfaces in their geometric models, however. Based on our evolving work, we describe the methodology and some key components of a solid modeler with parametric surface processing capability. Emphasis is put on a clean and extendible design that avoids the arbitrary restrictions which often are present in current systems.Item Set Operations of GWB(Blackwell Publishing Ltd and the Eurographics Association, 1983) Mantyla, M.A set operation algorithm that can be used to unite, intersect, or subtract solids with each other is an essential part of any solid modelling system. The problem is, however, difficult to solve while maintaining the well-formedness of the underlying solid representations. The Geometric Workbench, an experimental solid modeller constructed by the author, uses so-called Euler operators in its set operation algorithm to solve the problem of integrity. This leads to a robust algorithm with a simple overall structure and a clear separation between geometric and topological steps.