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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.
The default MeshSize for a CmpRegion is the
MeshSize of its first component Region.
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.
The default MeshSize for an Stc is the MeshSize of its encapsulated Region.
Copyright (C) 2021 East Asian Observatory
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A Library for Handling
World
Coordinate Systems
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