def __init__(self, input_, component=None, filetype='sdf', getshape=False):
# TODO: this should be using python NDF!
# If input is a string, assume it is either an NDF file or a
# FITS file, and read in the object
frameset = None
shape = None
# TODO: (Should useNDF interface once that is easy to install)
if isinstance(input_, str) and filetype == 'sdf':
try:
hdsloc = hds.open(input_, 'READ')
if component:
comps = component.split('.')
for c in comps:
hdsloc = hdsloc.find(c)
astwcs = hdsloc.find('WCS').find('DATA').get()
astwcs = [i.decode() for i in astwcs]
astwcs = ''.join([
i[1:] if i.startswith('+') else '\n' + i for i in astwcs
]).split('\n')
chan = Ast.Channel(astwcs)
frameset = chan.read()
except:
logger.error('Could not get a frameset from %s', input_)
hdsloc.annul()
raise
# Get the shape of the data.
if getshape:
try:
data = hdsloc.find('DATA_ARRAY').find('DATA').get()
shape = data.shape
except:
logger.debug('No data component found in input file.')
shape = None
hdsloc.annul()
# If its a fits file, try and read a
elif isinstance(input_, str) and filetype == 'fits':
from astropy.io import fits
from starlink import Atl
hdulist = fits.open(input_)
if not component:
component = 0
(frameset, encoding) = Atl.readfitswcs(hdulist[component])
shape = hdulist[component].shape
print('shape is', shape)
hdulist.close()
# Create low level object from frameset and shape
print(type(frameset), type(shape))
self._low_level_wcs = AstWCSLowLevel(frameset, arrayshape=shape)
self._info_string = None
# This script is featured on pyast issue page:
# https://github.com/timj/starlink-pyast/issues/8
# It also constructs the file tanflip.fits, which we use in the test suite.
# PyAst natively flips the order of RA and Dec when writing this file as a TAN WCS.
# This was a kind of input that wasn't otherwise featured in our test suite, but is
# apparently allowed by the fits standard. So I added it.
import starlink.Atl as Atl
import starlink.Ast as Ast
import astropy.io.fits as pyfits
import numpy
# http://fits.gsfc.nasa.gov/registry/tpvwcs/tpv.fits
hdu = pyfits.open('tpv.fits')[0]
fc = Ast.FitsChan(Atl.PyFITSAdapter(hdu))
wcs = fc.read()
# A random test position. The "true" RA, Dec values are taken from ds9.
'033009.340034', '-284350.811107', 418, 78, 2859.53882
x = 418
y = 78
true_ra = (3 + 30 / 60. + 9.340034 / 3600.) * numpy.pi / 12.
true_dec = -(28 + 43 / 60. + 50.811107 / 3600.) * numpy.pi / 180.
ra1, dec1 = wcs.tran(numpy.array([[x], [y]]))
print 'Initial read of tpv.fits:'
print 'error in ra = ', (ra1 - true_ra) * 180. * 3600. / numpy.pi, 'arcsec'
print 'error in dec = ', (dec1 - true_dec) * 180. * 3600. / numpy.pi, 'arcsec'
# Now cycle through writing and reading to a file
def wcsalign(hdu_in, header, outname=None, clobber=False):
"""
Align one FITS image to a specified header
Requires pyast.
Parameters
----------
hdu_in : `~astropy.io.fits.PrimaryHDU`
The HDU to reproject (must have header & data)
header : `~astropy.io.fits.Header`
The target header to project to
outname : str (optional)
The filename to write to.
clobber : bool
Overwrite the file ``outname`` if it exists
Returns
-------
The reprojected fits.PrimaryHDU
Credits
-------
Written by David Berry and adapted to functional form by Adam Ginsburg
([email protected])
"""
try:
import starlink.Ast as Ast
import starlink.Atl as Atl
except ImportError:
raise ImportError("starlink could not be imported, wcsalign is not "
"available")
# Create objects that will transfer FITS header cards between an AST
# FitsChan and the fits header describing the primary HDU of the
# supplied FITS file.
adapter_in = Atl.PyFITSAdapter(hdu_in)
hdu_ref = pyfits.PrimaryHDU(header=header)
adapter_ref = Atl.PyFITSAdapter(hdu_ref)
# Create a FitsChan for each and use the above adapters to copy all the
# header cards into it.
fitschan_in = Ast.FitsChan(adapter_in, adapter_in)
fitschan_ref = Ast.FitsChan(adapter_ref, adapter_ref)
# Get the flavour of FITS-WCS used by the header cards currently in the
# input FITS file. This is so that we can use the same flavour when we
# write out the modified WCS.
encoding = fitschan_in.Encoding
# Read WCS information from the two FitsChans. Additionally, this removes
# all WCS information from each FitsChan. The returned wcsinfo object
# is an AST FrameSet, in which the current Frame describes WCS coordinates
# and the base Frame describes pixel coodineates. The FrameSet includes a
# Mapping that specifies the transformation between the two Frames.
wcsinfo_in = fitschan_in.read()
wcsinfo_ref = fitschan_ref.read()
# Check that the input FITS header contained WCS in a form that can be
# understood by AST.
if wcsinfo_in is None:
raise ValueError(
"Failed to read WCS information from {0}".format(hdu_in))
# This is restricted to 2D arrays, so check theinput FITS file has 2
# pixel axes (given by Nin) and 2 WCS axes (given by Nout).
elif wcsinfo_in.Nin != 2 or wcsinfo_in.Nout != 2:
raise ValueError("{0} is not 2-dimensional".format(hdu_in))
# Check the reference FITS file in the same way.
elif wcsinfo_ref is None:
raise ValueError(
"Failed to read WCS information from {0}".format(hdu_ref))
elif wcsinfo_ref.Nin != 2 or wcsinfo_ref.Nout != 2:
raise ValueError("{0} is not 2-dimensional".format(hdu_ref))
# Proceed if the WCS information was read OK.
# Attempt to get a mapping from pixel coords in the input FITS file to
# pixel coords in the reference fits file, with alignment occuring by
# preference in the current WCS frame. Since the pixel coordinate frame
# will be the base frame in each Frameset, we first invert the
# FrameSets. This is because the Convert method aligns current Frames,
# not base frames.
wcsinfo_in.invert()
wcsinfo_ref.invert()
alignment_fs = wcsinfo_in.convert(wcsinfo_ref)
# Invert them again to put them back to their original state (i.e.
# base frame = pixel coords, and current Frame = WCS coords).
wcsinfo_in.invert()
wcsinfo_ref.invert()
# Check alignment was possible.
if alignment_fs is None:
raise Exception("Cannot find a common coordinate system shared by "
"{0} and {1}".format(hdu_in, hdu_ref))
else:
# Get the lower and upper bounds of the input image in pixel
# indices. All FITS arrays by definition have lower pixel bounds of
# [1, 1] (unlike NDFs). Note, unlike fits AST uses FITS ordering for
# storing pixel axis values in an array (i.e. NAXIS1 first, NAXIS2
# second, etc).
lbnd_in = [1, 1]
ubnd_in = [fitschan_in["NAXIS1"], fitschan_in["NAXIS2"]]
# Find the pixel bounds of the input image within the pixel coordinate
# system of the reference fits file.
(lb1, ub1, xl, xu) = alignment_fs.mapbox(lbnd_in, ubnd_in, 1)
(lb2, ub2, xl, xu) = alignment_fs.mapbox(lbnd_in, ubnd_in, 2)
# Calculate the bounds of the output image.
lbnd_out = [int(lb1), int(lb2)]
ubnd_out = [int(ub1), int(ub2)]
# Unlike NDFs, FITS images cannot have an arbitrary pixel origin so
# we need to ensure that the bottom left corner of the input image
# gets mapped to pixel [1,1] in the output. To do this we, extract the
# mapping from the alignment FrameSet and add on a ShiftMap (a mapping
# that just applies a shift to each axis).
shift = [1 - lbnd_out[0], 1 - lbnd_out[1]]
alignment_mapping = alignment_fs.getmapping()
shiftmap = Ast.ShiftMap(shift)
total_map = Ast.CmpMap(alignment_mapping, shiftmap)
# Modify the pixel bounds of the output image to take account of this
# shift of origin.
lbnd_out[0] += shift[0]
lbnd_out[1] += shift[1]
ubnd_out[0] += shift[0]
ubnd_out[1] += shift[1]
# Get the value used to represent missing pixel values
if "BLANK" in fitschan_in:
badval = fitschan_in["BLANK"]
flags = Ast.USEBAD
else:
badval = 0
flags = 0
# Resample the data array using the above mapping.
# total_map was pixmap; is this right?
(npix, out, out_var) = total_map.resample(lbnd_in, ubnd_in,
hdu_in.data, None,
Ast.LINEAR, None, flags,
0.05, 1000, badval, lbnd_out,
ubnd_out, lbnd_out, ubnd_out)
# Store the aligned data in the primary HDU, and update the NAXISi
# keywords to hold the number of pixels along each edge of the
# rotated image.
hdu_in.data = out
fitschan_in["NAXIS1"] = ubnd_out[0] - lbnd_out[0] + 1
fitschan_in["NAXIS2"] = ubnd_out[1] - lbnd_out[1] + 1
# The WCS to store in the output is the same as the reference WCS
# except for the extra shift of origin. So use the above shiftmap to
# remap the pixel coordinate frame in the reference WCS FrameSet. We
# can then use this FrameSet as the output FrameSet.
wcsinfo_ref.remapframe(Ast.BASE, shiftmap)
# Attempt to write the modified WCS information to the primary HDU (i.e.
# convert the FrameSet to a set of FITS header cards stored in the
# FITS file). Indicate that we want to use original flavour of FITS-WCS.
fitschan_in.Encoding = encoding
fitschan_in.clear('Card')
if fitschan_in.write(wcsinfo_ref) == 0:
raise Exception("Failed to convert the aligned WCS to Fits-WCS")
# If successful, force the FitsChan to copy its contents into the
# fits header, then write the changed data and header to the output
# FITS file.
else:
fitschan_in.writefits()
if outname is not None:
hdu_in.writeto(outname, clobber=clobber)
return hdu_in
from __future__ import print_function
try:
from astrop.io import fits as pyfits
except ImportError:
import pyfits
import starlink.Atl as Atl
import starlink.Ast as Ast
import matplotlib.pyplot
# Use pyfits to open a test files file
ffile = pyfits.open( 'starlink/ast/test/cobe.fit' )
# Use matplotlib to plot an annotated grid of the WCS coords
Atl.plotfitswcs( matplotlib.pyplot.figure(figsize=(8,8)).add_subplot(111),
[ 0.1, 0.1, 0.9, 0.9 ], ffile )
matplotlib.pyplot.show()
# Create a FitsChan telling it to use the pyfits primary hdu as the
# external data source and sink. Note, we take the default value of
# "True" for the "clear" property when creating the PyFITSADapater,
# which means the PyFITS header will be cleared immediately before
# the FitsChan.writefits() method writes to it.
adapter = Atl.PyFITSAdapter(ffile)
fc = Ast.FitsChan( adapter, adapter )
# Read the FrameSet from the FitsChan. This will read all headers from
# the pyfits hdu into the FitsChan, create a FrameSet from the WCS
# headers, and remove all WCS-related headers from the FitsChan (but not
# the pyfits primary hdu as yet).
fs = fc.read()
def rotate(infile, outfile, angle, xcen=None, ycen=None):
# Open the FITS file using pyfits. A list of the HDUs in the FITS file is
# returned.
hdu_list = pyfits.open(infile)
# Create an object that will transfer FITS header cards between an AST
# FitsChan and the PyFITS header describing the primary HDU of the
# supplied FITS file.
adapter = Atl.PyFITSAdapter(hdu_list[0])
# Create a FitsChan and use the above adapter to copy all the header
# cards into it.
fitschan = Ast.FitsChan(adapter, adapter)
# Get the flavour of FITS-WCS used by the header cards currently in the
# FitsChan. This is so that we can use the same flavour when we write
# out the modified WCS.
encoding = fitschan.Encoding
# Read WCS information from the FitsChan. Additionally, this removes all
# WCS information from the FitsChan. The returned wcsinfo object
# is an AST FrameSet, in which the current Frame describes WCS coordinates
# and the base Frame describes pixel coodineates. The FrameSet includes a
# Mapping that specifies the transformation between the two Frames.
wcsinfo = fitschan.read()
# Check that the FITS header contained WCS in a form that can be
# understood by AST.
if wcsinfo == None:
print("Failed to read WCS information from {0}".format(infile))
# Rotation is restricted to 2D arrays, so check the FITS file has 2 pixel
# axes (given by Nin) and 2 WCS axes (given by Nout).
elif wcsinfo.Nin != 2 or wcsinfo.Nout != 2:
print("{0} is not 2-dimensional".format(infile))
# Proceed if the WCS information was read OK.
else:
# Get the lower and upper bounds of the input image in pixel indices.
# All FITS arrays by definition have lower pixel bounds of [1,1] (unlike
# NDFs). Note, unlike pyfits AST uses FITS ordering for storing pixel axis
# values in an array (i.e. NAXIS1 first, NAXIS2 second, etc).
lbnd_in = [1, 1]
ubnd_in = [fitschan["NAXIS1"], fitschan["NAXIS2"]]
# Get the rotation angle and convert from degrees to radians.
angle = float(angle) * Ast.DD2R
# Construct a MatrixMap that rotates by the required angle, converted to radians.
sinang = math.sin(angle)
cosang = math.cos(angle)
pixmap = Ast.MatrixMap([[cosang, sinang], [-sinang, cosang]])
# If supplied, get the centre of rotation.
if (xcen is not None) and (ycen is not None):
# Create aShiftMap to shift the origin and combine it with the
# MatrixMap, to give the desired centre of rotation (shift,
# rotate, then shift back again).
shiftmap = Ast.ShiftMap([-xcen, -ycen])
pixmap = Ast.CmpMap(shiftmap, pixmap)
shiftmap.invert()
pixmap = Ast.CmpMap(pixmap, shiftmap)
# The dimensions of the output array are the same as the input array.
lbnd_out = lbnd_in
ubnd_out = ubnd_in
# If no centre of rotation was specified, we use the MatrixMap
# unchanged, and determine the bounds of the smallest output image that
# will hold the entire rotated input image. These are with respect to
# the pixel coordinates of the input array, and so some corners may have
# negative pixel coordinates.
else:
(lb1, ub1, xl, xu) = pixmap.mapbox(lbnd_in, ubnd_in, 1)
(lb2, ub2, xl, xu) = pixmap.mapbox(lbnd_in, ubnd_in, 2)
lbnd_out = [int(lb1), int(lb2)]
ubnd_out = [int(ub1), int(ub2)]
# Get the value used to represent missing pixel values
if "BLANK" in fitschan:
badval = fitschan["BLANK"]
flags = Ast.USEBAD
else:
badval = 0
flags = 0
# Resample the data array using the above mapping.
(npix, out, out_var) = pixmap.resample(lbnd_in, ubnd_in,
hdu_list[0].data, None,
Ast.LINEAR, None, flags, 0.05,
1000, badval, lbnd_out,
ubnd_out, lbnd_out, ubnd_out)
# Store the rotated data in the HDU, and update the NAXISi keywords
# to hold the number of pixels along each edge of the rotated image.
hdu_list[0].data = out
fitschan["NAXIS1"] = ubnd_out[0] - lbnd_out[0] + 1
fitschan["NAXIS2"] = ubnd_out[1] - lbnd_out[1] + 1
# Move the pixel origin of the output from "lbnd_out" to (1,1). Create a
# suitable ShiftMap, and append it to the total "old pixel coord" to
# "new pixel coords" mapping.
shiftmap = Ast.ShiftMap([-lbnd_out[0], -lbnd_out[1]])
pixmap = Ast.CmpMap(pixmap, shiftmap)
# Re-map the base Frame (i.e. the pixel coordinates Frame) so that it
# refers to the new data grid instead of the old one.
wcsinfo.remapframe(Ast.BASE, pixmap)
# Attempt to write the modified WCS information to the primary HDU (i.e.
# convert the FrameSet to a set of FITS header cards stored in the
# FITS file). Indicate that we want to use original flavour of FITS-WCS.
fitschan.Encoding = encoding
fitschan.clear('Card')
if fitschan.write(wcsinfo) == 0:
print("Failed to convert the rotated WCS to Fits-WCS")
# If successfull, force the FitsCHan to copy its contents into the
# PyFITS header, then write the changed data and header to the output
# FITS file.
else:
fitschan.writefits()
hdu_list.writeto(outfile, clobber=True, output_verify='ignore')
# - Requires pyast version 2.3 import pyfits import sys import math import starlink.Ast as Ast import starlink.Atl as Atl # Open the FITS file using pyfits. A list of the HDUs in the FITS file is # returned. hdu_list = pyfits.open( sys.argv[1] ) # Create an object that will transfer FITS header cards between an AST # FitsChan and the PyFITS header describing the primary HDU of the # supplied FITS file. adapter = Atl.PyFITSAdapter( hdu_list[ 0 ] ) # Create a FitsChan and use the above adapter to copy all the header # cards into it. fitschan = Ast.FitsChan( adapter, adapter ) # Get the flavour of FITS-WCS used by the header cards currently in the # FitsChan. This is so that we can use the same flavour when we write # out the modified WCS. encoding = fitschan.Encoding # Read WCS information from the FitsChan. Additionally, this removes all # WCS information from the FitsChan. The returned wcsinfo object # is an AST FrameSet, in which the current Frame describes WCS coordinates # and the base Frame describes pixel coodineates. The FrameSet includes a # Mapping that specifies the transformation between the two Frames.
# This script is featured on pyast issue page:
# https://github.com/timj/starlink-pyast/issues/8
# It also constructs the file tanflip.fits, which we use in the test suite.
# PyAst natively flips the order of RA and Dec when writing this file as a TAN WCS.
# This was a kind of input that wasn't otherwise featured in our test suite, but is
# apparently allowed by the fits standard. So I added it.
import starlink.Atl as Atl
import starlink.Ast as Ast
import astropy.io.fits as pyfits
import numpy
# http://fits.gsfc.nasa.gov/registry/tpvwcs/tpv.fits
hdu = pyfits.open('tpv.fits')[0]
fc = Ast.FitsChan(Atl.PyFITSAdapter(hdu))
wcs = fc.read()
# A random test position. The "true" RA, Dec values are taken from ds9.
'033009.340034', '-284350.811107', 418, 78, 2859.53882
x = 418
y = 78
true_ra = (3 + 30/60. + 9.340034/3600.) * numpy.pi / 12.
true_dec = -(28 + 43/60. + 50.811107/3600.) * numpy.pi / 180.
ra1, dec1 = wcs.tran( numpy.array([ [x], [y] ]))
print 'Initial read of tpv.fits:'
print 'error in ra = ',(ra1-true_ra) * 180.*3600./numpy.pi, 'arcsec'
print 'error in dec = ',(dec1-true_dec) * 180.*3600./numpy.pi, 'arcsec'
# Now cycle through writing and reading to a file