Tessellation (computer graphics)

Source: Wikipedia, the free encyclopedia.
A simple tessellation pipeline rendering a smooth sphere from a crude cubic vertex set using a subdivision method

In

Direct3D 11.[1][2]

In graphics rendering

A key advantage of tessellation for

3D polygon mesh and its silhouette edges based on control parameters (often camera distance). In previously leading realtime techniques such as parallax mapping and bump mapping, surface details could be simulated at the pixel level, but silhouette edge detail was fundamentally limited by the quality of the original dataset.[3]

In

Tessellation Control Shader and a set of four tessellation parameters.[6]

In computer-aided design

In computer-aided design the constructed design is represented by a boundary representation topological model, where analytical 3D surfaces and curves, limited to faces, edges, and vertices, constitute a continuous boundary of a 3D body. Arbitrary 3D bodies are often too complicated to analyze directly. So they are approximated (tessellated) with a

finite element analysis.[citation needed
]

The mesh of a surface is usually generated per individual faces and edges (approximated to polylines) so that original limit vertices are included into mesh. To ensure that approximation of the original surface suits the needs of further processing, three basic parameters are usually defined for the surface mesh generator:

  • The maximum allowed distance between the planar approximation polygon and the surface (known as "sag"). This parameter ensures that mesh is similar enough to the original analytical surface (or the polyline is similar to the original curve).
  • The maximum allowed size of the approximation polygon (for triangulations it can be maximum allowed length of triangle sides). This parameter ensures enough detail for further analysis.
  • The maximum allowed angle between two adjacent approximation polygons (on the same face). This parameter ensures that even very small humps or hollows that can have significant effect to analysis will not disappear in mesh.

An algorithm generating a mesh is typically controlled by the above three and other parameters. Some types of computer analysis of a constructed design require an adaptive mesh refinement, which is a mesh made finer (using stronger parameters) in regions where the analysis needs more detail.[1][2]

See also

References

  1. ^ a b The OpenGL® Graphics System: A Specification (Version 4.0 (Core Profile) - March 11, 2010)
  2. ^ a b MSDN: Tessellation Overview
  3. ISBN 978-0321637635
    .
  4. ^ a b Abi-Chahla, Fedy (16 September 2008). "Tessellation". Tom's Hardware. Retrieved 27 April 2013.
  5. ^ Tariq, Sara. "D3D11 Tessellation" (PDF). Nvidia. Retrieved 27 April 2013.
  6. ^ "Tessellation". OpenGL. Retrieved 27 April 2013.
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