標準號：BS ISO 10303-42-1994
中文標準名稱：工業(yè)自動化系統(tǒng)和集成.產(chǎn)品數(shù)據(jù)表述和交換.一般集成資源:地理和拓撲表述法
英文標準名稱：Industrial automation systems and integration. Product data representation and exchange. Integrated generic resources. Geometric and topological representation
標準類型：N10
發(fā)布日期：1995/10/15 12:00:00
實施日期：1995/10/15 12:00:00
中國標準分類號：N10
國際標準分類號：35.040;35.240.50
適用范圍：This part of ISO 10303 specifies the resource constructs for the explicit geometric and topological representation of the shape of a product. The scope is determined by the requirements for the explicit representation of an ideal product model; tolerances and implicit forms of representation in terms of features are out of scope. The geometry in clause 4 and the topology in clause 5 are available for use independently and are also extensively used by the various forms of geometric shape model in clause 6. In addition, this part of ISO 10303 specifies specialisations of the concepts of representation where the elements of representation are geometric. 1 Geometry The following are within the scope of the geometry schema: - definition of points, vectors, parametric curves and parametric surfaces; - definition of transformation operators; - points defined directly by their coordinate values or in terms of the parameters of an existing curve or surface; - definition of conic curves and elementary surfaces; - definition of curves defined on a parametric surface; - definition of general parametric spline curves and surfaces; - definition of point, curve and surface replicas; - definition of offset curves and surfaces; - definition of intersection curves. The following are outside the scope of this part of ISO 10303: - all other forms of procedurally defined curves and surfaces; - curves and surfaces which do not have a parametric form of representation; - any form of explicit representation of a ruled surface. NOTE - For a ruled surface the geometry is critically dependent upon the parametrisation of the boundary curves and the method of associating pairs of points on the two curves. A ruled surface with B-spline boundary curves can however be exactly represented by the B-spline surface entity. 2 Topology The following are within the scope of the topology schema: - definition of the fundamental topological entities vertex, edge, and face, each with a specialised subtype to enable it to be associated with the geometry of a point, curve, or surface, respectively; - collections of the basic entities to form topological structures of path, loop and shell and constraints to ensure the integrity of these structures; - orientation of topological entities. 3 Geometric Shape Models The following are within the scope of the geometric model schema: - data describing the precise geometric form of three-dimensional solid objects; - constructive solid geometry (CSG) models; - definition of CSG primitives and half-spaces; - creation of solid models by sweeping operations; - manifold boundary representation (B-rep) models; - constraints to ensure the integrity of B-rep models; - surface models; - wireframe models; - geometric Sets; - creation of a replica of a solid model in a new location. The following are outside the scope of this part of ISO 10303: - non-manifold boundary representation models; - spatial occupancy forms of solid models (such as octree models); - assemblies and mechanisms.