3D computer graphics (in contrast to 2D computer graphics) are graphics that use a three-dimensional representation of geometric
data that is stored in the computer for the purposes of performing calculations and rendering 2D images. Such images may be for later display or for real-time viewing. ...Animating objects that appear in a three-dimensional space. They can be rotated and moved like real objects. 3D animation is at the heart of games and virtual reality, but it may also be used in presentation graphics to add flair to the visuals.Form of animated graphics that has replaced "stop-motion" animation of scale-model puppets or drawings. Efforts to lessen the labour and costs of animation have led to simplification and computerization. Computers can be used in every step of sophisticated animation — for example, to automate the movement of the rostrum camera or to supply the in-between drawings for full animation. When a three-dimensional figure is translated into computer terms (digitized), the computer can generate and display a sequence of images that seem to move or rotate the object through space. Hence computer animation can simulate highly complex motion for medical and other scientific researchers, as well as for feature films.The duration of the animation is defined in seconds, The frame rate (fps) dictates the number of frames displayed per second of animation. Most commercially available computer animation systems are based on animating with keyframes. At first, this seems like the same thing as keyframes in traditional hand-drawn animation, but it is slightly different, and therefore, you should approach your animation differently. In hand-drawn animation, you work on the basic poses of the scene first, drawing poses of the entire character so the timing and acting can be worked out with a minimum of drawings created. Once the poses are finalized, then the inbetween drawings are created to complete the action. With computer animation, keyframes are values at certain frames for the articulation controls of a model, which are usually set up in a hierarchy. The computer calculates the inbetweens values based on a spline curve connecting the keyframe values.One of the biggest differences between hand-drawn animation and computer animation is the fact that computer animation is truly three dimensional.Since computer animation is truly 3-D, you can re-use the animation of a scene or parts of the animation and not tell that it is the exact same motion.Many times, if you simply look at a scene of animation from a different camera angle, it will look completely different.Sometimes, it may seem too similar, so just vary the timing of the motion or change the motion of an arm or head and it will cease to resemble the original. This is great for crowd shots, where the re-use of animation is an easy way to keep the crowd alive.The computer gives the ability to create images that look absolutely real. Especially with the latest techniques in rendering, texture mapping, ray tracing and radiosity, you can make an object look just like it’s made of marble or rubber or whatever you wish. But to make it look like marble or rubber when it is in motion, has very little to do with the way the object is rendered. It has everything to do with the way the object is animated. It is animation that gives an object its physical properties. More that anything else, the timing of the movement of an object defines the weight of that object.Two objects, identical in size and shape, can appear to have two vastly different weights by manipulating timing alone. The heavier an object is, the greater its mass, and the more force that is required to change its motion. A heavy body is slower to accelerate than a light one. It takes a large force to get a bowling ball moving; but once moving, it tends to keep moving at the same speed and requires some force to stop it.When dealing with heavy objects, one must allow plenty of time and force to start, stop or change their movements, in order to make their weight look convincing. Light objects have much less resistance to change of movement and thus require much less time to start moving. The flick of a finger is enough to make a balloon accelerate away. When moving, it has little momentum and even the friction of the air quickly slows it up.The way an object behaves on the screen, the effect of weight that it gives, depend mostly on the spacing of the poses and less on the poses themselves. Again, no matter how well rendered a bowling ball may be, it does not look like a bowling ball if it doesn’t behave like one when it is animated.The proper timing of a motion can also contribute greatly to the feeling of size and scale of an object or character.