#### Description:

This attribute controls how many points are used when creating a mesh of points covering the boundary or volume of a Region. Such a mesh is returned by the astGetRegionMesh method. The boundary mesh is also used when testing for overlap between two Regions: each point in the bomdary mesh of the first Region is checked to see if it is inside or outside the second Region. Thus, the reliability of the overlap check depends on the value assigned to this attribute. If the value used is very low, it is possible for overlaps to go unnoticed. High values produce more reliable results, but can result in the overlap test being very slow. The default value is 200 for two dimensional Regions and 2000 for three or more dimensional Regions (this attribute is not used for 1-dimensional regions since the boundary of a simple 1-d Region can only ever have two points). A value of five is used if the supplied value is less than five.

Type:

  Integer.

#### Applicability

##### Region

All Regions have this attribute.

##### CmpRegion

The default MeshSize for a CmpRegion is the MeshSize of its first component Region.

##### Moc

The MeshSize attribute is ignored when forming a mesh covering the boundary of a Moc. Instead, the mesh will include a point for the exterior corners of every HEALPix cell (at the order specified by attribute MaxOrder) that touches the boundary. Note, this applies only to meshes covering the boundary of the Moc - the MeshSize attribute is used as normal when forming a mesh covering the area of the Moc.

##### Stc

The default MeshSize for an Stc is the MeshSize of its encapsulated Region.
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