add_distort.pro

basic median filter simulation

 pro add_distort, hdr, astr
; NAME:
;    ADD_DISTORT
; PURPOSE:
;    Add the distortion parameters in an astrometry structure to a FITS header.
; EXPLANATION:
;    PUTAST currently does not add the SIP (Spitzer Imaging Polynomial) 
;    distortion parameters when writing an astrometry structure to a FITS 
;    header.    Therefore, to include the distortion polynomial, one should
;    call add_distort after putast. 
;
;    IDL> putast,h ,astr0
;    IDL> add_distort,h,astr0
;
; CALLING SEQUENCE:
;     add_distort, hdr, astr    
;
; INPUTS:
;     HDR -  FITS header, string array.   HDR will be updated to contain
;             the supplied astrometry.
;     ASTR - IDL structure containing values of the astrometry parameters
;            CDELT, CRPIX, CRVAL, CTYPE, LONGPOLE, PV2 and DISTORT
;            See EXTAST.PRO for more info about the structure definition
;
; PROCEDURES USED:
;       SXADDPAR, TAG_EXIST()
; REVISION HISTORY:
;       Written by W. Landsman  May 2005
;-
 npar = N_params()

 if ( npar LT 2 ) then begin    ;Was header supplied?
        print,'Syntax: ADD_DISTORT, Hdr, astr'
        return
 endif

  add_distort = tag_exist(astr,'distort')
 
 if add_distort then begin
   sxaddpar,hdr,'CTYPE1','RA---TAN-SIP' 
   sxaddpar,hdr,'CTYPE2','DEC--TAN-SIP' 
    distort = astr.distort
     a_dimen = size(distort.a,/dimen) 
     b_dimen = size(distort.b,/dimen)
     ap_dimen = size(distort.ap,/dimen) 
     bp_dimen = size(distort.bp,/dimen)

  if a_dimen[0] GT 0 then begin
        a_order = a_dimen[0]-1 
        sxaddpar, hdr, 'A_ORDER', a_order, /savec, $
                  'polynomial order, axis 1, detector to sky '
        for i=0, a_order do begin
            for j = 0, a_order do begin
             aij = distort.a[i,j]
             if aij NE 0.0 then $
                sxaddpar, hdr, 'A_' + strtrim(i,2)+ '_' + strtrim(j,2), aij, $
                ' distortion coefficient', /savec
             endfor
         endfor
  endif

  if b_dimen[0] GT 0 then begin
        b_order = b_dimen[0]-1 
        sxaddpar, hdr, 'B_ORDER', a_order, /savec , $
                  'polynomial order, axis 2, detector to sky'
        for i=0, b_order do begin
            for j = 0, b_order do begin
             bij = distort.b[i,j]
             if bij NE 0.0 then $
                sxaddpar, hdr, 'B_' + strtrim(i,2)+ '_' + strtrim(j,2), bij, $
                ' distortion coefficient', /savec
             endfor
         endfor
  endif

  if ap_dimen[0] GT 0 then begin
        ap_order = ap_dimen[0]-1 
        sxaddpar, hdr, 'AP_ORDER', a_order, /savec, $
                  ' polynomial order, axis 1, sky to detector '
        for i=0, ap_order do begin
            for j = 0, ap_order do begin
             apij = distort.ap[i,j]
             if apij NE 0.0 then $
                sxaddpar, hdr, 'AP_' + strtrim(i,2)+ '_' + strtrim(j,2), apij, $
                ' distortion coefficient', /savec
             endfor
         endfor
  endif


  if bp_dimen[0] GT 0 then begin
        bp_order = bp_dimen[0]-1 
        sxaddpar, hdr, 'BP_ORDER', a_order, /savec, $
                  ' polynomial order, axis 2, sky to detector '
        for i=0, bp_order do begin
            for j = 0, bp_order do begin
             bpij = distort.bp[i,j]
             if bpij NE 0.0 then $
                sxaddpar, hdr, 'BP_' + strtrim(i,2)+ '_' + strtrim(j,2), bpij, $
                ' distortion coefficient', /savec
             endfor
         endfor
  endif

 endif

 return
 end