Create regions to group elements together logically, and ensure that individual mesh elements are not missed when you assign them a property.
Regions are always planar. Since mesh elements may not be coplanar, specify a tolerance within which adjacent mesh elements are considered part of the same plane to ensure that they are included in the same region.
There are two types of tolerance to choose from: angular or planar. The Angular tolerance enables you to specify the maximum allowable angle between mesh elements, in degrees, as shown in the image below left. The Planar tolerance enables you to specify the maximum allowable distance from the same plane between mesh elements, in mm, as shown in the image below, right. Use angular tolerances for parts with large curved surfaces. Use planar tolerances to preserve the shape of your part.
