Edge Angle:

Edge angle:

The angle at which smooth edges become sharp.

When smooth shading it makes sense to preserve some "sharp" angles, since most real-life objects have sharp as well as smooth edges.

This is done by computing the angle between the outward normals of adjacent facets at vertices, and only averaging if this is less than the current Edge angle . This effect is evident in the images of the head above: the ridge of the nose is "sharp" whereas the rest of the face is "smooth".

Edge angle can lie in the range 0 - 180 deg, (values > 90 deg are significant for 3D elements). The default of 60 degrees looks reasonably natural for most objects. 0 degrees is equivalent to Flat shading, and 180 degrees will eliminate all sharp edges.