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PcdCen(axis)
-
Centre coordinates of pincushion/barrel distortion
- Description:
- This attribute specifies the centre of the pincushion/barrel
distortion implemented by a PcdMap. It takes a separate value for
each axis of the PcdMap so that, for instance, the settings
"PcdCen(1)=345.0,PcdCen(2)=-104.4" specify that the pincushion
distortion is centred at positions of 345.0 and -104.4 on axes 1 and 2
respectively. This attribute is set when a PcdMap is created, but may
later be modified. If the attribute is cleared, the default value for
both axes is zero.
- Type:
- Floating point.
- Class Applicability:
-
PcdMap
-
All PcdMaps have this attribute.
- Notes:
- If no axis is specified, (e.g. "PcdCen" instead of
"PcdCen(2)"), then a "set" or "clear" operation will affect
the attribute value of both axes, while a "get" or "test"
operation will use just the PcdCen(1) value.
Next: Permute - Permute axis order?
Up: AST Attribute Descriptions
Previous: PVi_m - FITS-WCS projection parameters
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