Buitenvlak

Buitenvlak is a Dutch geometric term for a flat surface that forms part of the boundary of a three-dimensional object. The word combines buiten (outside) and vlak (flat surface or plane). In the context of polyhedra, the buitenvlakken are the polygonal faces that bound the solid; their union forms the boundary surface that separates the interior from the exterior.

Each buitenvlak lies in a plane and meets other buitenvlakken along edges. The orientation of a buitenvlak is given by its outward normal, a perpendicular vector pointing away from the interior of the solid.

Common solids illustrate the concept: a cube has six buitenvlakken; a tetrahedron has four; in general a polyhedron has F buitenvlakken, where F is the number of faces. For closed convex polyhedra, Euler's formula V − E + F = 2 relates the numbers of vertices V, edges E and faces F.

Buitenvlakken are essential in practical applications such as computer graphics, CAD, and 3D printing, where the shape and orientation of the exterior surface determine rendering, manufacturing, and analysis. In these contexts, the quality of the surface mesh, including the arrangement and consistency of the buitenvlakken, affects accuracy and performance.

See also: vlak, polyhedron, surface, normal vector, Euler characteristic.