(Term of geometry/computer graphics)
An vector perpendicular to a surface. At the same time, the direction of this vector determines the orientation of the surface. In the case of polygons, this direction is usually determined by the right hand rule.
In computer graphics, manipulations of the normal vector are often used as a way to simulate geometrical detail on otherwise planar surfaces. In this case, a function will determine small aberrations of the true direction of the normal vector on every point of the surface, in order special create highlight or shadow effects. If eg. the vector is slightly shifted in accordance to a sinus function, then the surface will appear in a rendered image, as if it were made of corrugated material (except for the edges).
In the Radiance software, texture modifiers are used for this purpose.
right hand rule
|normal vector||Der Normalvektor|
|surface normal||Die Flächennormale|