Computer representation of surfacesIn technical applications of 3D computer graphics (CAx) such as computer-aided design and computer-aided manufacturing, surfaces are one way of representing objects. The other ways are wireframe (lines and curves) and solids. Point clouds are also sometimes used as temporary ways to represent an object, with the goal of using the points to create one or more of the three permanent representations. If one considers a local parametrization of a surface: then the curves obtained by varying u while keeping v fixed are coordinate lines, sometimes called the u flow lines.
Christian cross variantsThe Christian cross, with or without a figure of Christ included, is the main religious symbol of Christianity. A cross with a figure of Christ affixed to it is termed a crucifix and the figure is often referred to as the corpus (Latin for "body"). The term Greek cross designates a cross with arms of equal length, as in a plus sign, while the Latin cross designates a cross with an elongated descending arm. Numerous other variants have been developed during the medieval period.
RadianceIn radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Radiance is used to characterize diffuse emission and reflection of electromagnetic radiation, and to quantify emission of neutrinos and other particles. The SI unit of radiance is the watt per steradian per square metre (). It is a directional quantity: the radiance of a surface depends on the direction from which it is being observed.
CrossA cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a saltire in heraldic terminology. The cross has been widely recognized as a symbol of Christianity from an early period. Before then, it was a pagan religious symbol throughout Europe and western Asia. The effigy of a man hanging on a cross was set up in the fields to protect the crops.
