Rasterisation

Rasterisation (or rasterization) is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image (pixels or dots) for output on a video display or printer, or for storage in a bitmap file format. It refers to both rasterisation of models and 2D rendering primitives such as polygons, line segments, etc.

In normal usage, the term refers to the popular rendering algorithm for displaying 3D models on a computer. Rasterisation is currently the most popular technique for producing real-time 3D computer graphics. Real-time applications need to respond immediately to user input, and generally need to produce frame rates of at least 30 frames per second to achieve smooth animation.

Compared with other rendering techniques such as ray tracing, rasterisation is extremely fast. However, rasterization is simply the process of computing the mapping from scene geometry to pixels and does not prescribe a particular way to compute the color of those pixels. Shading, including programmable shading, may be based on physical light transport, or artistic intent.

The term "rasterisation" in general can be applied to any process by which vector information (or other procedural description) can be converted into a raster format.

The process of rasterising 3D models onto a 2D plane for display on a computer screen ("screen space") is often carried out by fixed function hardware within the graphics pipeline. This is because there is no motivation for modifying the techniques for rasterisation used at render time and a special-purpose system allows for high efficiency.

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