Portal de Periódicos da CAPES

gnomes: an object-oriented nonmanifold geometric engine

1995; Elsevier BV; Volume: 27; Issue: 11 Linguagem: Inglês

10.1016/0010-4485(95)00022-4

1879-2685

Ram D. Sriram, Albert Kai-Sun Wong, Li-Xing He,

Advanced Theoretical and Applied Studies in Material Sciences and Geometry

Geometric modelling is an integral part of most cad/cam applications. However, there is not a widespread and integrated use of geometric modelling throughout the product lifecycle. The primary reason for this is the differences in the modelling requirements of applications that are used at the various stages of the product development cycle. The paper describes a geometric engine, gnomes, which provides a geometric modelling framework that can be shared by many applications. This is achieved using a unified representation which can model a large class of point sets that includes nonmanifold point sets, nonclosed point sets, and sets with cracks or missing points. Powerful high-level modelling operations (Boolean, topological, and structural operations) which are useful for constructing more complex models or interrogating the geometric models have been implemented. gnomes also provides various database facilities through the use of a distributed object-oriented database management system. These facilities include support for persistent gnomes objects, long and short duration transaction management for concurrent access by multiple applications, a general query facility, and a version and configuration management facility which can be used to record the evolution of gnomes models. The gnomes architecture is based on object-oriented principles, and it provides clear abstractions in a small set of encapsulated classes. The goal in developing gnomes is to provide a geometric engine that is reasonably easy to understand and easily extensible, and that can be used as a basic building block of a collaborative engineering environment. The paper describes the gnomes representation scheme, its object-oriented design, and sample applications which illustrate various gnomes functionalities.