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MeshSize
-
Number of points used to represent the boundary of a Region
- 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.
- Class Applicability:
-
Region
-
All Regions have this attribute.
-
CmpRegion
-
The default MeshSize for a CmpRegion is the MeshSize of its
first component Region.
-
Stc
-
The default MeshSize for an Stc is the MeshSize of its
encapsulated Region.
Next: MinAxes - Minimum number of Frame axes to match
Up: AST Attribute Descriptions
Previous: MaxAxes - Maximum number of Frame axes to match
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2009 Science \& Technology Facilities Council