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from __future__ import division
import numpy as np
from matplotlib import pyplot as plt
import pyfits
import string
from stsci.tools import parseinput, irafglob
from stwcs.distortion import utils
from stwcs import updatewcs, wcsutil
from stwcs.wcsutil import altwcs
def vmosaic(fnames, outwcs=None, ref_wcs=None, ext=None, extname=None, undistort=True, wkey='V', wname='VirtualMosaic', plot=False, clobber=False):
"""
Create a virtual mosaic using the WCS of the input images.
Parameters
----------
fnames: a string or a list
a string or a list of filenames, or a list of wcsutil.HSTWCS objects
outwcs: an HSTWCS object
if given, represents the output tangent plane
if None, the output WCS is calculated from the input observations.
ref_wcs: an HSTWCS object
if output wcs is not given, this will be used as a reference for the
calculation of the output WCS. If ref_wcs is None and outwcs is None,
then the first observation in th einput list is used as reference.
ext: an int, a tuple or a list
an int - represents a FITS extension, e.g. 0 is the primary HDU
a tuple - uses the notation (extname, extver), e.g. ('sci',1)
Can be a list of integers or tuples representing FITS extensions
extname: string
the value of the EXTNAME keyword for the extensions to be used in the mosaic
undistort: boolean (default: True)
undistort (or not) the output WCS
wkey: string
default: 'V'
one character A-Z to be used to record the virtual mosaic WCS as
an alternate WCS in the headers of the input files.
wname: string
default: 'VirtualMosaic
a string to be used as a WCSNAME value for the alternate WCS representign
the virtual mosaic
plot: boolean
if True and matplotlib is installed will make a plot of the tangent plane
and the location of the input observations.
clobber: boolean
This covers the case when an alternate WCS with the requested key
already exists in the header of the input files.
if clobber is True, it will be overwritten
if False, it will compute the new one but will not write it to the headers.
Notes
-----
The algorithm is:
1. If output WCS is not given it is calculated from the input WCSes.
The first image is used as a reference, if no reference is given.
This represents the virtual mosaic WCS.
2. For each input observation/chip, an HSTWCS object is created
and its footprint on the sky is calculated (using only the four corners).
3. For each input observation the footprint is projected on the output
tangent plane and the virtual WCS is recorded in the header.
"""
wcsobjects = readWCS(fnames, ext, extname)
if outwcs != None:
outwcs = outwcs.deepcopy()
else:
if ref_wcs != None:
outwcs = utils.output_wcs(wcsobjects, ref_wcs=ref_wcs, undistort=undistort)
else:
outwcs = utils.output_wcs(wcsobjects, undistort=undistort)
if plot:
outc=np.array([[0.,0], [outwcs._naxis1, 0],
[outwcs._naxis1, outwcs._naxis2],
[0, outwcs._naxis2], [0, 0]])
plt.plot(outc[:,0], outc[:,1])
for wobj in wcsobjects:
outcorners = outwcs.wcs_sky2pix(wobj.calcFootprint(),1)
if plot:
plt.plot(outcorners[:,0], outcorners[:,1])
objwcs = outwcs.deepcopy()
objwcs.wcs.crpix = objwcs.wcs.crpix - (outcorners[0])
updatehdr(wobj.filename, objwcs,wkey=wkey, wcsname=wname, ext=wobj.extname, clobber=clobber)
return outwcs
def updatehdr(fname, wcsobj, wkey, wcsname, ext=1, clobber=False):
hdr = pyfits.getheader(fname, ext=ext)
all_keys = list(string.ascii_uppercase)
if wkey.upper() not in all_keys:
raise KeyError, "wkey must be one character: A-Z"
if wkey not in altwcs.available_wcskeys(hdr):
if not clobber:
raise ValueError, "wkey %s is already in use. Use clobber=True to overwrite it or specify a different key." %wkey
else:
altwcs.deleteWCS(fname, ext=ext, wcskey='V')
f = pyfits.open(fname, mode='update')
hwcs = wcs2header(wcsobj)
wcsnamekey = 'WCSNAME' + wkey
f[ext].header.update(key=wcsnamekey, value=wcsname)
for k in hwcs.keys():
f[ext].header.update(key=k[:7]+wkey, value=hwcs[k])
f.close()
def wcs2header(wcsobj):
h = wcsobj.to_header()
if wcsobj.wcs.has_cd():
altwcs.pc2cd(h)
h.update('CTYPE1', 'RA---TAN')
h.update('CTYPE2', 'DEC--TAN')
norient = np.rad2deg(np.arctan2(h['CD1_2'],h['CD2_2']))
#okey = 'ORIENT%s' % wkey
okey = 'ORIENT'
h.update(key=okey, value=norient)
return h
def readWCS(input, exts=None, extname=None):
if isinstance(input, str):
if input[0] == '@':
# input is an @ file
filelist = irafglob.irafglob(input)
else:
try:
filelist, output = parseinput.parseinput(input)
except IOError: raise
elif isinstance(input, list):
if isinstance(input[0], wcsutil.HSTWCS):
# a list of HSTWCS objects
return input
else:
filelist = input[:]
wcso = []
fomited = []
# figure out which FITS extension(s) to use
if exts == None and extname == None:
#Assume it's simple FITS and the data is in the primary HDU
for f in filelist:
try:
wcso = wcsutil.HSTWCS(f)
except AttributeError:
fomited.append(f)
continue
elif exts != None and validateExt(exts):
exts = [exts]
for f in filelist:
try:
wcso.extend([wcsutil.HSTWCS(f, ext=e) for e in exts])
except KeyError:
fomited.append(f)
continue
elif extname != None:
for f in filelist:
fobj = pyfits.open(f)
for i in range(len(fobj)):
try:
ename = fobj[i].header['EXTNAME']
except KeyError:
continue
if ename.lower() == extname.lower():
wcso.append(wcsutil.HSTWCS(f,ext=i))
else:
continue
fobj.close()
if fomited != []:
print "These files were skipped:"
for f in fomited:
print f
return wcso
def validateExt(ext):
if not isinstance(ext, int) and not isinstance(ext, tuple) \
and not isinstance(ext, list):
print "Ext must be integer, tuple, a list of int extension numbers, \
or a list of tuples representing a fits extension, for example ('sci', 1)."
return False
else:
return True
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