Phong Shading

Phong shading is a method from the 3D computer graphics to provide polygon surfaces with color shades. It was named after its developer Bùi Tường Phong, which it introduced in 1975.

When Phong Shading ( vertices ) of a polygon are calculated the normals and then extended by a calculation of interpolated normals along the edges for each projection of the polygon to a pixel at the corners. Color strengths are calculated from the interpolated normals. The results of the Phong shading are better quality than that of the Gouraud shading, but the mathematical calculations are more complicated. The increased interpolation of the normals as faceted surfaces of an object represented appear to be very soft.

Phong shading is not to be confused with the Phong lighting model. It is for the latter to a lighting model and not an interpolative shading technique. However, it is possible to combine the two techniques.