Wire-frame model

A wire frame model is a visual presentation of a three dimensional or physical object used in 3D computer graphics. It is created by specifying each edge of the physical object where two mathematically continuous smooth surfaces meet, or by connecting an object's constituent vertices using straight lines or curves. The object is projected onto the computer screen by drawing lines at the location of each edge.

Using a wire frame model allows visualization of the underlying design structure of a 3D model. Traditional 2-dimensional views and drawings can be created by appropriate rotation of the object and selection of hidden line removal via cutting planes.

Since wireframe renderings are relatively simple and fast to calculate, they are often used in cases where a high screen frame rate is needed (for instance, when working with a particularly complex 3D model, or in real-time systems that model exterior phenomena). When greater graphical detail is desired, surface textures can be added automatically after completion of the initial rendering of the wireframe. This allows the designer to quickly review changes or rotate the object to new desired views without long delays associated with more realistic rendering.

The wire frame format is also well suited and widely used in programming tool paths for DNC (Direct Numerical Control) machine tools.

Wire frame models were used extensively in video games to represent 3D objects during the 1980s and early 1990s when properly filled 3D objects would have been too complex to calculate and draw with the computers of the time. Wireframe models are also used as the input for CAM(computer-aided manufacturing).

There are mainly three types of 3D CAD models. Wireframe is one of them and it is most abstract and least realistic. Other types of 3D CAD models are surface and solid. This method of modelling consists only lines,points and curves defining the edges of a object.

Simple example of wireframe model

It is one of the oldest method of representing objects.It consists of details, given in form of two tables :-1)vertex table and 2)edge table.Vertex table consists of co ordinate values of each vertex with reference to origin.While edge table consists of vertices in which the given edge terminates.But it does not contain face information.

Methods for creating 3D wireframe

Extrusion: It is technique for creating a 3D wireframe model by copying a 2D profile and extending it to a depth defined the operator. The result is a 3D wireframe of the profile.
Rotation: Rotation produces wireframe models by rotating a cross section or profile of the part about an axis.It is similar to extrusion except it is swept about an axis.
Extrusion with scale: Extrusion with scale technique comprises of defining the depth along with the facility of enlarging scale uniformly.
Using primitive shapes to build models.

Use of wireframe model

Viewing the model from any desired point-This can be obtained by changing line of sight.
To produce standard orthographic and auxillary views:-Orthographic views are created by changing the line of sight so that it is perpendicular to the front,top and profile faces of the model for creating front view(elevation),top view(plan) and side view respectively.After the orthographic views are created,they must be edited to remove extraneous lines and to add hidden and centre lines so the drawing conforms with the standards.
To produce exploded and perspective view more easily.
To analyse distances within the structure and checking tolerances and interference.
To decrease number of prototypes required.
Editing the model:-Some CAD systems can automatically remove hidden lines using a command called hide.