It is a 2D modeling system plus the addition of some more extra primitives. 3D system includes all types of user-defined systems. The standard coordinate system used is called a world coordinate system. Whereas the user-defined coordinate system is called a user coordinate system.
It is of three types
- Solid Modelling System
- Surface Modelling System
- Wireframe Models
Wireframe Models: It has a lot of other names also i.e.
- Stick figure model
- Polygonal net
- Polygonal mesh
- Visible line detection method
Wireframe model consists of vertex, edge (line) and polygons. Edge is used to join vertex. Polygon is a combination of edges and vertices. The edges can be straight or curved. This model is used to define computer models of parts, especially for computer-assisted drafting systems.
Wireframe models are Skelton of lines. Each line has two endpoints. The visibility or appearance or look of the surface can be should using wireframe. If any hidden section exists that will be removed or represented using dashed lines. For determining hidden surface, hidden lines methods or visible line methods are used.