Three Dimensional GraphicsThe threedimensional transformations are extensions of twodimensional transformation. In 2D two coordinates are used, i.e., x and y whereas in 3D three coordinates x, y, and z are used. For three dimensional images and objects, threedimensional transformations are needed. These are translations, scaling, and rotation. These are also called as basic transformations are represented using matrix. More complex transformations are handled using matrix in 3D. The 2D can show twodimensional objects. Like the Bar chart, pie chart, graphs. But some more natural objects can be represented using 3D. Using 3D, we can see different shapes of the object in different sections. In 3D when a translation is done we need three factors for rotation also, it is a component of three rotations. Each can be performed along any three Cartesian axis. In 3D also we can represent a sequence of transformations as a single matrix. Computer Graphics uses CAD. CAD allows manipulation of machine components which are 3 Dimensional. It also provides automobile bodies, aircraft parts study. All these activities require realism. For realism 3D is required. In the production of a realistic 3D scene from 2D is tough. It require three dimension, i.e., depth. 3D GeometryThree dimension system has three axis x, y, z. The orientation of a 3D coordinate system is of two types. Righthanded system and lefthanded system. In the right handed system thumb of right hand points to positive zdirection and left hand system thumb point to negative two directions. Following figure show righthand orientation of the cube. Using righthanded system coordinates of corners A, B, C, D of the cube Point A x, y, z Producing realism in 3D: The threedimensional objects are made using computer graphics. The technique used for two Dimensional displays of three Dimensional objects is called projection. Several types of projection are available, i.e.,
1. Parallel Projection: In this projection point on the screen is identified within a point in the threedimensional object by a line perpendicular to the display screen. The architect Drawing, i.e., plan, front view, side view, elevation are nothing but lines of parallel projections. 2. Perspective Projection: This projection has a property that it provides idea about depth. Farther the object from the viewer, smaller it will appear. All lines in perspective projection converge at a center point called as the center of projection. 3. Orthographic Projection: It is simplest kind of projection. In this, we take a top, bottom, side view of the object by extracting parallel lines from the object. Three Dimensional ModelsThe techniques for generating different images of a solid object depend upon the type of object. Two viewing techniques are available for viewing threedimensional objects.
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