Viewing frustum

In <a href="/facts/3D_computer_graphics/zlWW6eaF">3D computer graphics</a>, a viewing frustum or view frustum is the region of space in the modeled world that may appear on the screen; it is the <a href="/facts/Field_of_view_in_video_games/k7mdAClD">field of view</a> of a <a href="/facts/Perspective_(graphical)/zkNx7Wpf">perspective</a> <a href="/facts/Virtual_camera_system/fCkGL0Gj">virtual camera system</a>.
The view frustum is typically obtained by taking a geometrical <a href="/facts/Frustum/TEfLWynX">frustum</a>—that is a truncation with parallel planes—of the pyramid of vision, which is the adaptation of (idealized) <a href="/facts/Cone_of_vision/QPjsVG1T">cone of vision</a> that a camera or eye would have to the rectangular <a href="/facts/Viewport/6IawV5Kw">viewports</a> typically used in computer graphics. Some authors use pyramid of vision as a synonym for view frustum itself, i.e. consider it <a href="/facts/Truncation_(geometry)/DYb589Je">truncated</a>.
The exact shape of this region varies depending on what kind of camera lens is being simulated, but typically it is a frustum of a rectangular pyramid (hence the name). The planes that cut the frustum perpendicular to the viewing direction are called the near plane and the far plane. Objects closer to the camera than the near plane or beyond the far plane are not drawn. Sometimes, the far plane is placed infinitely far away from the camera so all objects within the frustum are drawn regardless of their distance from the camera.
<a href="/facts/Hidden-surface_determination/hk9dqmDE"> Viewing-frustum culling</a> is the process of removing from the <a href="/facts/Rendering_(computer_graphics)/YYxfnmAq">rendering</a> process those objects that lie completely outside the viewing frustum. Rendering these objects would be a waste of resources since they are not directly visible. To make culling fast, it is usually done using <a href="/facts/Bounding_volume/2okceuxx">bounding volumes</a> surrounding the objects rather than the objects themselves.

Viewing frustum open-in-new

Viewing frustum