The controls for Round Corners soften the edges of objects without your having to alter geometry.
One reason computer-generated imagery can look unrealistic is that by default, the edges of objects are geometrically sharp. In the real world, most edges are slightly rounded, chamfered, worn, or filleted in some manner. Such edges tend to catch the light and create highlights that make edges more visually appealing.
Many ProMaterials can create the illusion of rounded edges at render time. This feature is intended primarily to speed up modeling, so that you need not explicitly fillet or chamfer edges of an object such as a tabletop.
Left: No round corners
Right: Round corners
The round corners effect is not a displacement, and it has no effect on geometry: It is merely a shading effect, such as bump mapping.
The rounding effect happens to convex corners and surfaces that actually intersect. Concave corners that merely touch will not display the effect. To get the effect to work in concave corners, the objects must be pushed into each other a little. The effect is intended for straight edges and is not guaranteed to work properly for highly curved, complex intersections.
There are three controls for round corners:
Specifies the radius of the filleted corners and/or edges. Default=0.25.
Click the button to apply a map to this parameter (in the Slate Material Editor, you can also wire the Round Corners Source socket). Mapping the Fillet Radius creates variations in the amount of corner rounding.
In the following image, the melted chocolate is rounded off against the submerged objects even though they use different materials. In actuality, the melted chocolate is a completely flat plane.
Objects in melted chocolate
