ISO 10303-42:2022

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 objects; 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.