Regions are areas or selections of connected entities that may include both planar and non-planar surfaces.
Working with regions is often easier than working with a mesh because it is possible to group mesh elements together logically and to ensure that individual mesh elements are not omitted from receiving a property.
Regions are always planar. Since mesh elements may deviate slightly from being coplanar, you can specify a tolerance within which adjacent mesh elements will be considered part of the same plane, and hence become part of the same region. There are two types of tolerance to choose from when creating regions: angular or planar. Angular tolerance specifies the maximum allowable angle between mesh elements in degrees (see image on left, below). Planar tolerance specifies the maximum allowable distance from the same plane between mesh elements in mm (see image on right, below). Angular tolerances may be used when your part has large curved surfaces. Planar tolerances may be used when you want to preserve the shape of your part.
