A wire-frame model, also wireframe model, is a visual representation of a three-dimensionalphysical 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 lines or curves. The object is projected into screen space and rendered by drawing lines at the location of each edge. The term "wire frame" comes from designers using metal wire to represent the three-dimensional shape of solid objects. 3D wire framecomputer models allow for the construction and manipulation of solids and solid surfaces. 3D solid modeling efficiently draws higher quality representations of solids than conventional line drawing. Using a wire-frame model allows for the visualization of the underlying design structure of a 3D model. Traditional two-dimensional views and drawings/renderings can be created by the appropriate rotation of the object, and the selection of hidden line removal via cutting planes. Since wire-frame renderings are relatively simple and fast to calculate, they are often used in cases where a relatively high screen frame rate is needed. When greater graphical detail is desired, surfacetextures can be added automatically after the completion of the initial rendering of the wire frame. This allows a designer to quickly review solids, or rotate objects to different views without the long delays associated with more realistic rendering, or even the processing of faces and simple flat shading. The wire frame format is also well-suited and widely used in programming tool paths for direct numerical controlmachine tools. Hand-drawn wire-frame-like illustrations date back as far as the Italian Renaissance. Wire-frame models were also 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. Wire-frame models are also used as the input for computer-aided manufacturing. There are three main types of 3D computer-aided design models; wire frame is the most abstract and least realistic. The other types are surface and solid. The wire-frame method of modelling consists of only lines and curves that connect the points or vertices and thereby define the edges of an object.
Introduction
Wireframing is one of the methods used in geometric modelling systems. A wireframe model represents the shape of a solid object with its characteristic lines and points. There are two types of wireframe modelling: Pro's and Con's. In Pro's user gives a simple input to create a shape. It is useful in developing systems. While in Con's wireframe model, it does not include information about inside and outside boundary surfaces. Today, wireframe models are used to define complex solid objects. The designer makes a wireframe model of a solid object, and then the CAD operator reconstructs the object, including detailed analysis. This technique has some advantages: generally the 3-dimensional solid objects are complex, but wireframe models can be viewed in 1 dimension, improving comprehensibility; the solid object can be modified further; the designer can ignore the geometry inside a surface while in solid modelling the designer has to give consistent geometry for all details; wireframe models require less memory space and CPU capacity.
Simple example of wireframe model
An object is specified by two tables: Vertex Table, and, Edge Table. The vertex table consists of three-dimensional coordinate values for each vertex with reference to the origin. Edge table specifies the start and end vertices for each edge. A naive interpretation could create a wire-frame representation by simply drawing straight lines between the screen coordinates of the appropriate vertices using the edge list. Unlike representations designed for more detailed rendering, face information is not specified. Appropriate calculations have to be performed to transform the 3D coordinates of the vertices into 2D screen coordinates.
