computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great deal ...

, image order

algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...

iterate over the

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the s ...

s in the image to be produced, rather than the elements in the scene to be rendered. Object order algorithms are those that iterate over the elements in the scene to be rendered, rather than the pixels in the image to be produced. For typical rendering applications, the scene contains many fewer elements (e.g.

geometric primitive In vector computer graphics, CAD systems, and geographic information systems, geometric primitive (or prim) is the simplest (i.e. 'atomic' or irreducible) geometric shape that the system can handle (draw, store). Sometimes the subroutines tha ...

s) than image pixels. In those cases, object order algorithms are usually most efficient (e.g. scan conversion or shear warp). But when the scene complexity exceeds that of the image, such as is the case often in

volume rendering In scientific visualization and computer graphics, volume rendering is a set of techniques used to display a 2D projection of a 3D discretely sampled data set, typically a 3D scalar field. A typical 3D data set is a group of 2D slice imag ...

, then image order algorithms (e.g., ray casting) may be more efficient.

References

{{Reflist 3D rendering