Non-photorealistic Rendering

Non- photorealistic rendering (short: NPR) is a method for generating ( " rendering " ) computer graphics which do not comply aware the physically correct image of a model.

Overview

While it is the goal of most algorithms for rendering computer graphics to produce a result which comes as close as possible to the model of a photo, this restriction is lifted at NPR. Using current algorithms, it is so, starting from the same three-dimensional models, for example, possible to create images that are similar, such as line drawings, watercolors, oil paintings. appearance This kind of algorithms that do not represent geometrically correct forms of photo realistic, are the most frequent and (mostly ) possible as a purely image-based versions ( ie without considering the underlying geometry). However, there are other areas of the NPR such as non- photorealistic lighting or not photorealistic projection: this is refracted by optical laws and enabling representations which are physically impossible in reality. Examples are ( diverging parallel lines, objects with increasing distance from the camera larger) inverse perspective, several camera positions that are combined in one image, not planar projection.

Misconceptions

Often, methods that are possible using traditional photographic approaches, as NPR referred to. In part, these are to processes in which, despite the possible application in photography no mathematical image is available ( the sharp projection on a curved surface is quite possible to a certain extent, for example, if a sufficiently small aperture in image magnification is selected, but a physical image does not correspond to it), some of it is image-based distortions, which are not represented in the "classic" photographic processes ( examples of these are ) the bromoil and Sabattier process, or is physically possible, but the users of computer technology does not seem to known methods, such as the image correction on Scheimpflug principle. All of these, the term sometimes referred to by quite as " photo-realistic " to significant end, representation methods in the literature as NPR.

Application

The application of the NPR is diverse: line drawings are in the field of technical guides often better understood as photos, even in medical books of photos taken rather an exception. In other areas, where it was customary to make drawings by hand, today CAD programs are used. Here, in order, the same results as before to achieve is often also necessary NPR ( an example is the drawing of architects called, in which the level of detail of a line drawing status of planning reflects ). Furthermore, NPR plays in the artistic field and in computer games a huge role, see also Cel Shading.