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

1. Solid Modelling System
2. Surface Modelling System
3. Wireframe Models

Wireframe Models: It has a lot of other names also i.e.

Java Try Catch

1. Edge vertex models
2. Stick figure model
3. Polygonal net
4. Polygonal mesh
5. 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.

Advantage

1. It is simple and easy to create.
2. It requires little computer time for creation.
3. It requires a short computer memory, so the cost is reduced.
4. Wireframe provides accurate information about deficiencies of the surface.
5. It is suitable for engineering models composed of straight lines.
6. The clipping process in the wireframe model is also easy.
7. For realistic models having curved objects, roundness, smoothness is achieved.

Disadvantage

1. It is given only information about the outlook if do not give any information about the complex part.
2. Due to the use of lines, the shape of the object lost in cluttering of lines.
3. Each straight line will be represented as collections of four fold lines using data points. So complexity will be increased.