Modeling data

3D modeling & numerical simulation

BSpline Surface

Bezier Surface

vertex, edges, wires...

Open CASCADE	Showroom	Get Open CASCADE	Developer Corner	Support	About us
Technical overview Areas of use Advantages Public license FAQ	Screenshots Shape factory Shape gallery Demonstrations	System requirements What's new Download Center CD-ROM	Documentation Getting started Forum Open Source community	Training and e-learning A la Carte Support Value-added software Client Area	Company Profile Contacts and Locations Customers News

Home / Open CASCADE / Technical overview / Modeling data

Modeling data

Modeling Data supplies data structures to represent 2D and 3D geometric and topological models.
These structures are organized in the following libraries:

2D Geometry
This library provides 2D geometric data structures and topological orientation.

The geometric package Geom2D provides STEP-compliant 2D geometric data structures handled by reference.

These objects are parameterized, and are as a result, oriented. They include Bezier, BSpline, and offset curves, and provide functions for conversion of Geom2D objects to gp (basic geometry) objects, which are non-oriented and non-parameterized.

3D Geometry
This library provides 3D geometric data structures and topological orientation.

The geometric package Geom3D provides STEP-compliant 3D geometric data structures handled by reference. These objects are parameterized and are as a result, oriented. They include Bezier, BSpline, offset curves, and surfaces, and provide functions for conversion of Geom3D objects to gp (basic geometry) objects, which are non-oriented and non-parameterized.
The geometric properties package GeomLProp allows you to compute such properties as:
- Derivative vectors of a parametric point on a curve or surface
- Tangent vectors of a parametric point on a curve or surface
- Normal
- Curvature

Topology
The topological library allows you to build pure topological data structures.

Topology defines relationships between simple geometric entities. In this way, you can model complex shapes as assemblies of simpler entities. Thanks to the built-in non-manifold (or mixed-dimensional) feature, you can build models mixing:
- 0D entities such as points
- 1D entities such as curves
- 2D entities such as surfaces
- 3D enitities such as volumes.

You can, for example, represent a single object made of several distinct bodies containing embedded curves and surfaces connected or not to the outer boundary.

Abstract topological data structure describes a basic entity, the shape, which can be divided into the following component topologies:
- Vertex, a zero-dimensional shape corresponding to a point in geometry
- Edge, a shape corresponding to a curve, and bound by a vertex at each extremity
- Wire, a sequence of edges connected by their vertices
- Face, part of a plane (in 2D geometry) or a surface (in 3D geometry) bounded by a closed wire
- Shell, a collection of faces connected by some of the edges of their wire boundaries
- Solid, part of 3D space bound by a shell
- Compound solid, a collection of solids

The wire and the solid can be either infinite or closed.

A face with 3D underlying geometry may also refer to a collection of connected triangles that approximate the underlying surface. The surfaces can be undefined leaving the faces represented by triangles only. If so, the model is purely polyhedral.

As well as the above data structures and that for a generalized shape, this library also provides resources to define the location of shapes.

login
pass

	registration

Benefits
The foundations for Modeling Data C++ libraries were established 10 years ago, which insures the robustness of the model and the perpetuity of data.

Geometry and Topology both depend on the step standard and are defined in separate modules.

The data structure is incremental (sharing of the entities)

Topology defined in Open CASCADE allows regular and multidimensional descriptions of objects: physical objects (manifold objects) or abstract objects (non-manifold objects) and it thus covers a large number of professional domains.