In 3D computer graphics, a micropolygon is a polygon that is at least as small as the size of a pixel in the output image. The concept of micropolygons was developed to be used by the Reyes algorithm. At rendering time, the geometric primitive is tessellated into a rectangular grid of tiny four-sided polygons or micropolygons. A shader later assigns colors to the vertices of these faces. Commonly the size of these micropolygons is the same as the area of a pixel. Using micropolygons allows the renderer to create a highly detailed image.

Shaders that operate on micropolygons can process an entire grid at once in SIMD fashion. This often leads to faster shader execution, and allows shaders to compute spatial derivatives (e.g. for texture filtering) by comparing values at neighboring micropolygon vertices.

A renderer that uses micropolygons can support displacement mapping simply by perturbing micropolygon vertices during shading.

Further reading

• Steve Upstill: The RenderMan Companion: A Programmer's Guide to Realistic Computer Graphics, Addison-Wesley, ISBN 0-201-50868-0
• Anthony A. Apodaca, Larry Gritz: Advanced RenderMan: Creating CGI for Motion Pictures, Morgan Kaufmann Publishers, ISBN 1-55860-618-1

3D computer graphics