 non-photorealistic rendering (npr) is an area of computer graphics that focuses on enabling a wide variety of expressive styles for digital art. in contrast to traditional computer graphics, which has focused on photorealism, npr is inspired by artistic styles such as painting, drawing, technical illustration, and animated cartoons. npr has appeared in movies and video games in the form of "toon shading", as well as in scientific visualization, architectural illustration and experimental animation. an example of a modern use of this method is that of cel-shaded animation. ==history== the term "non-photorealistic rendering" was probably coined by david salesin and georges winkenbach in a 1994 paper.computer-generated pen-and-ink illustration", by winkenbach and salesin, siggraph 94 many researchers find the terminology to be unsatisfying; some of the criticisms are as follows: * the term "photorealism" has different meanings for graphics researchers and artists. for artists, who are the target consumers of npr techniques, it refers to a school of painting that focuses on reproducing the effect of a camera lens, with all the distortion and hyper-reflections that it involves. for graphics researchers, it refers to an image that is visually indistinguishable from reality. in fact, graphics researchers lump the kinds of visual distortions that are used by photorealist painters into non-photorealism. * describing something by what it is not is problematic. equivalent comparisons might be "non-elephant biology", or "non-geometric mathematics". npr researchers have stated that they expect the term will disappear eventually, and be replaced by the more general term "computer graphics", with "photorealistic graphics" being used to describe traditional computer graphics. * many techniques that are used to create 'non-photorealistic' images are not rendering techniques. they are modelling techniques, or post-processing techniques. while the latter are coming to be known as 'image-based rendering', sketch-based modelling techniques, cannot technically be included under this heading, which is very inconvenient for conference organisers. the first conference on non-photorealistic animation and rendering included a discussion of possible alternative names. among those suggested were "expressive graphics", "artistic rendering", "non-realistic graphics", "art-based rendering", and "psychographics". all of these terms have been used in various research papers on the topic, but the term npr seems to have nonetheless taken hold. the first technic
3D_rendering