Types of 2D and 3D graphics

By the way it is created, computer graphics is two-dimensional (2D) or three-dimensional (3D). In 3D graphics the surface of an object is covered with a net of small triangles, then painted, lit and given shadows; this step is called rendering and needs many calculations. Three-dimensional graphics is used in animation, computer games and virtual reality; in a virtual-reality headset a separate picture is made for each eye. 2D graphics has three kinds. In raster graphics the picture consists of pixels in rows and columns: photographs, scanners and phone cameras work this way; its size is the number of columns and rows and its density is measured in dpi. A raster can hold a high-quality photo, but it needs much memory and becomes blurry when enlarged. In vector graphics the picture is stored as a list of simple shapes (segment, circle, curve) and their parameters; it takes little space and keeps its quality when the scale changes, but it cannot store a photograph; fonts are also drawn from vectors. In fractal graphics shapes made of self-similar parts (a snowflake, the branching of a tree) are created from simple formulas; the term “fractal” was introduced to science in 1975.