From 40e5a5811c6ffce9b0974e93cdd927cbcf60c157 Mon Sep 17 00:00:00 2001 From: Joe Hunkeler Date: Tue, 11 Aug 2015 16:51:37 -0400 Subject: Repatch (from linux) of OSX IRAF --- math/slalib/doc/unpcd.hlp | 57 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 math/slalib/doc/unpcd.hlp (limited to 'math/slalib/doc/unpcd.hlp') diff --git a/math/slalib/doc/unpcd.hlp b/math/slalib/doc/unpcd.hlp new file mode 100644 index 00000000..26654492 --- /dev/null +++ b/math/slalib/doc/unpcd.hlp @@ -0,0 +1,57 @@ +.help unpcd Jun99 "Slalib Package" +.nf + + SUBROUTINE slUPCD (DISCO,X,Y) + + - - - - - - + U P C D + - - - - - - + + Remove pincushion/barrel distortion from a distorted [x,y] + to give tangent-plane [x,y]. + + Given: + DISCO d pincushion/barrel distortion coefficient + X,Y d distorted coordinates + + Returned: + X,Y d tangent-plane coordinates + + Notes: + + 1) The distortion is of the form RP = R*(1 + C*R**2), where R is + the radial distance from the tangent point, C is the DISCO + argument, and RP is the radial distance in the presence of + the distortion. + + 2) For pincushion distortion, C is +ve; for barrel distortion, + C is -ve. + + 3) For X,Y in "radians" - units of one projection radius, + which in the case of a photograph is the focal length of + the camera - the following DISCO values apply: + + Geometry DISCO + + astrograph 0.0 + Schmidt -0.3333 + AAT PF doublet +147.069 + AAT PF triplet +178.585 + AAT f/8 +21.20 + JKT f/8 +13.32 + + 4) The present routine is an approximate inverse to the + companion routine slPCD, obtained from two iterations + of Newton's method. The mismatch between the slPCD and + slUPCD routines is negligible for astrometric applications; + to reach 1 milliarcsec at the edge of the AAT triplet or + Schmidt field would require field diameters of 2.4 degrees + and 42 degrees respectively. + + P.T.Wallace Starlink 1 August 1994 + + Copyright (C) 1995 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp -- cgit