Agrondvlak

Agrondvlak is a term used in Dutch-language geometry and related fields to denote the base or ground plane of a three-dimensional object or scene. It provides a reference surface for height measurements, projections, and construction, and is typically treated as flat and infinite unless specified otherwise.

In analytic geometry, a plane is defined by a point P0 on the plane and a normal vector n perpendicular to the plane. The aggrondvlak consists of all points P satisfying n · (P - P0) = 0. In practical use, the aggrondvlak is often taken as the horizontal plane with equation z = 0 in a Cartesian coordinate system, making it the reference for vertical height.

The plane can be finite when it forms the base of a solid, for example the base polygon of a prism or pyramid. Distances, projections, and areas are frequently computed with respect to the aggrondvlak by projecting points orthogonally onto the plane or by intersecting lines with the plane.

In computer graphics, CAD and architecture, the aggrondvlak serves as the default reference plane for placing objects, rendering shadows, and defining footprints or contact areas. It can be transformed by translation and rotation alongside the object, after which it may no longer be horizontal.

See also: grondvlak, basisvlak, referentievlak.