Computer animation is the process used for generating animated images. For 3D animations, objects are modelled and 3D figures are rigged with a virtual skeleton. For 2D figure animations, separate objects and transparent layers are used with or without that virtual skeleton. Then
parts of the figure are then moved by the animator on key frames. The differences in appearance between key frames are automatically calculated by the computer (tweening or morphing). Finally, the animation is rendered.
For 3D animations, all frames must be rendered after the modeling is complete.