Monthly Archives: December 2010

Normal Vector


 N=[f_x(x_0,y_0); f_y(x_0,y_0); -1],

The normal vector, often simply called the “normal,” to a surface is a vector perpendicular to it. Often, the normal unit vector is desired, which is sometimes known as the “unit normal.” The terms “normal vector” and “normalized vector” should not be confused, especially since unit norm vectors might be called “normalized normal vectors” without redundancy. When normals are considered on closed surfaces, the inward-pointing normal (pointing towards the interior of the surface) and outward-pointing normal are usually distinguished. The normal vector is commonly denoted N or n, with a hat sometimes (but not always) added (i.e., N^^ and n^^) to explicitly indicate a unit normal vector.