This document specifies the integrated generic resource constructs for geometric and topological representation. The following are within the scope of this document:
The following are in the scope of the geometry schema:
- definition of points, vectors, parametric curves and parametric surfaces;
- definition of finite volumes with internal parametrisation;
- 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, surfaces and volumes;
- definition of locally refined spline curves, surfaces and volumes;
- definition of point, curve and surface replicas;
- definition of offset curves and surfaces;
- definition of intersection curves.
The following are in 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;
- the association of faces with geometric volumes;
- orientation of topological entities.
The following are in the scope of the geometric model schema:
- data describing the precise geometric form of three-dimensional solid
- constructive solid geometry (CSG) models;
- CSG models in two-dimensional space;
- 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;
- tessellated geometry;
- the association of tessellated geometry with exact geometry.
The following are in the scope of the scan data 3d shape model schema:
- representation of a shape as a cloud of points produced by a scanning process.
The following are outside the scope of this document:
- 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.
- spatial occupancy forms of solid models (such as octree models);
- geometric tolerances;
- implicit forms of representation in terms of features;
- assemblies and mechanisms.
Status: PublishedPublication date: 2022-12
Edition: 7Number of pages: 11
Technical Committee: ISO/TC 184/SC 4 Industrial data