/usr/lib/python3/dist-packages/astLib/astWCS.py is in python3-astlib 0.10.0-1.
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(c) 2007-2012 Matt Hilton
(c) 2013-2018 Matt Hilton & Steven Boada
U{http://astlib.sourceforge.net}
This is a higher level interface to some of the routines in PyWCSTools
(distributed with astLib).
PyWCSTools is a simple SWIG wrapping of WCSTools by Jessica Mink
(U{http://tdc-www.harvard.edu/software/wcstools/}). It is intended is to make
this interface complete enough such that direct use of PyWCSTools is
unnecessary.
@var NUMPY_MODE: If True (default), pixel coordinates accepted/returned by
routines such as L{astWCS.WCS.pix2wcs}, L{astWCS.WCS.wcs2pix} have (0, 0)
as the origin. Set to False to make these routines accept/return pixel
coords with (1, 1) as the origin (i.e. to match the FITS convention,
default behaviour prior to astLib version 0.3.0).
@type NUMPY_MODE: bool
"""
#-----------------------------------------------------------------------------
from astropy.io import fits as pyfits
from PyWCSTools import wcs
import numpy
import locale
# if True, -1 from pixel coords to be zero-indexed like numpy. If False, use
# FITS convention.
NUMPY_MODE = True
# Check for the locale bug when decimal separator isn't '.' (atof used in
# libwcs)
lconv = locale.localeconv()
if lconv['decimal_point'] != '.':
print("WARNING: decimal point separator is not '.' - astWCS coordinate conversions will not work.")
print("Workaround: after importing any modules that set the locale (e.g. matplotlib) do the following:")
print(" import locale")
print(" locale.setlocale(locale.LC_NUMERIC, 'C')")
#-----------------------------------------------------------------------------
class WCS:
"""This class provides methods for accessing information from the World
Coordinate System (WCS) contained in the header of a FITS image.
Conversions between pixel and WCS coordinates can also be performed.
To create a WCS object from a FITS file called "test.fits", simply:
WCS=astWCS.WCS("test.fits")
Likewise, to create a WCS object from the pyfits.header of "test.fits":
img=pyfits.open("test.fits")
header=img[0].header
WCS=astWCS.WCS(header, mode = "pyfits")
"""
def __init__(self, headerSource, extensionName = 0, mode = "image", zapKeywords = []):
"""Creates a WCS object using either the information contained in the
header of the specified .fits image, or from a pyfits.header object.
Set mode = "pyfits" if the headerSource is a pyfits.header.
For some images from some archives, particular header keywords such as
COMMENT or HISTORY may contain unprintable strings. If you encounter
this, try setting zapKeywords = ['COMMENT', 'HISTORY'] (for example).
@type headerSource: string or pyfits.header
@param headerSource: filename of input .fits image, or a pyfits.header
object
@type extensionName: int or string
@param extensionName: name or number of .fits extension in which image
data is stored
@type mode: string
@param mode: set to "image" if headerSource is a .fits file name, or
set to "astropy" if headerSource is an astropy.io.fits.Header object
(setting to this to "pyfits" is equivalent, for backwards
compatibility with existing code)
@type zapKeywords: list
@param: zapKeywords: keywords to remove from the header before making
astWCS object.
@note: The meta data provided by headerSource is stored in WCS.header
as a pyfits.header object.
"""
self.mode = mode
self.headerSource = headerSource
self.extensionName = extensionName
if self.mode == "image":
img = pyfits.open(self.headerSource)
# silentfix below won't deal with unprintable strings
# so here we optionally remove problematic keywords
for z in zapKeywords:
if z in img[self.extensionName].header.keys():
for count in range(img[self.extensionName].header.count(z)):
img[self.extensionName].header.remove(z)
img.verify('silentfix') # solves problems with non-standard headers
self.header = img[self.extensionName].header
img.close()
elif self.mode == "astropy" or self.mode == "pyfits":
for z in zapKeywords:
if z in self.headerSource.keys():
for count in range(self.headerSource.count(z)):
self.headerSource.remove(z)
self.header=headerSource
self.updateFromHeader()
def copy(self):
"""Copies the WCS object to a new object.
@rtype: astWCS.WCS object
@return: WCS object
"""
# This only sets up a new WCS object, doesn't do a deep copy
ret = WCS(self.headerSource, self.extensionName, self.mode)
# This fixes copy bug
ret.header = self.header.copy()
ret.updateFromHeader()
return ret
def updateFromHeader(self):
"""Updates the WCS object using information from WCS.header. This
routine should be called whenever changes are made to WCS keywords in
WCS.header.
"""
# Updated for pyfits 3.1+
newHead=pyfits.Header()
for i in self.header.items():
if len(str(i[1])) < 70:
if len(str(i[0])) <= 8:
newHead.append((i[0], i[1]))
else:
newHead.append(('HIERARCH '+i[0], i[1]))
# Workaround for ZPN bug when PV2_3 == 0 (as in, e.g., ESO WFI images)
if "PV2_3" in list(newHead.keys()) and newHead['PV2_3'] == 0 and newHead['CTYPE1'] == 'RA---ZPN':
newHead["PV2_3"]=1e-15
cardstring = ""
for card in newHead.cards:
cardstring = cardstring+str(card)
self.WCSStructure = wcs.wcsinit(cardstring)
def getCentreWCSCoords(self):
"""Returns the RA and dec coordinates (in decimal degrees) at the
centre of the WCS.
@rtype: list
@return: coordinates in decimal degrees in format [RADeg, decDeg]
"""
full = wcs.wcsfull(self.WCSStructure)
RADeg = full[0]
decDeg = full[1]
return [RADeg, decDeg]
def getFullSizeSkyDeg(self):
"""Returns the width, height of the image according to the WCS in
decimal degrees on the sky (i.e., with the projection taken into
account).
@rtype: list
@return: width and height of image in decimal degrees on the sky in
format [width, height]
"""
full = wcs.wcsfull(self.WCSStructure)
width = full[2]
height = full[3]
return [width, height]
def getHalfSizeDeg(self):
"""Returns the half-width, half-height of the image according to the
WCS in RA and dec degrees.
@rtype: list
@return: half-width and half-height of image in R.A., dec. decimal
degrees in format [half-width, half-height]
"""
half = wcs.wcssize(self.WCSStructure)
width = half[2]
height = half[3]
return [width, height]
def getImageMinMaxWCSCoords(self):
"""Returns the minimum, maximum WCS coords defined by the size of the
parent image (as defined by the NAXIS keywords in the image header).
@rtype: list
@return: [minimum R.A., maximum R.A., minimum Dec., maximum Dec.]
"""
# Get size of parent image this WCS is taken from
maxX = self.header['NAXIS1']
maxY = self.header['NAXIS2']
minX = 1.0
minY = 1.0
if NUMPY_MODE == True:
maxX = maxX-1
maxY = maxY-1
minX = minX-1
minY = minY-1
bottomLeft = self.pix2wcs(minX, minY)
topRight = self.pix2wcs(maxX, maxY)
xCoords = [bottomLeft[0], topRight[0]]
yCoords = [bottomLeft[1], topRight[1]]
xCoords.sort()
yCoords.sort()
return [xCoords[0], xCoords[1], yCoords[0], yCoords[1]]
def wcs2pix(self, RADeg, decDeg):
"""Returns the pixel coordinates corresponding to the input WCS
coordinates (given in decimal degrees). RADeg, decDeg can be single
floats, or lists or numpy arrays.
@rtype: list
@return: pixel coordinates in format [x, y]
"""
if type(RADeg) == numpy.ndarray or type(RADeg) == list:
if type(decDeg) == numpy.ndarray or type(decDeg) == list:
pixCoords = []
for ra, dec in zip(RADeg, decDeg):
pix = wcs.wcs2pix(self.WCSStructure, float(ra), float(dec))
# Below handles CEA wraparounds
if pix[0] < 1:
xTest = ((self.header['CRPIX1'])-(ra-360.0) /
self.getXPixelSizeDeg())
if xTest >= 1 and xTest < self.header['NAXIS1']:
pix[0] = xTest
if NUMPY_MODE == True:
pix[0] = pix[0]-1
pix[1] = pix[1]-1
pixCoords.append([pix[0], pix[1]])
else:
pixCoords = (wcs.wcs2pix(self.WCSStructure, float(RADeg),
float(decDeg)))
# Below handles CEA wraparounds
if pixCoords[0] < 1:
xTest = ((self.header['CRPIX1'])-(RADeg-360.0) /
self.getXPixelSizeDeg())
if xTest >= 1 and xTest < self.header['NAXIS1']:
pixCoords[0] = xTest
if NUMPY_MODE == True:
pixCoords[0] = pixCoords[0]-1
pixCoords[1] = pixCoords[1]-1
pixCoords = [pixCoords[0], pixCoords[1]]
return pixCoords
def pix2wcs(self, x, y):
"""Returns the WCS coordinates corresponding to the input pixel
coordinates.
@rtype: list
@return: WCS coordinates in format [RADeg, decDeg]
"""
if type(x) == numpy.ndarray or type(x) == list:
if type(y) == numpy.ndarray or type(y) == list:
WCSCoords = []
for xc, yc in zip(x, y):
if NUMPY_MODE == True:
xc += 1
yc += 1
WCSCoords.append(wcs.pix2wcs(self.WCSStructure, float(xc),
float(yc)))
else:
if NUMPY_MODE == True:
x += 1
y += 1
WCSCoords = wcs.pix2wcs(self.WCSStructure, float(x), float(y))
return WCSCoords
def coordsAreInImage(self, RADeg, decDeg):
"""Returns True if the given RA, dec coordinate is within the image
boundaries.
@rtype: bool
@return: True if coordinate within image, False if not.
"""
pixCoords = wcs.wcs2pix(self.WCSStructure, RADeg, decDeg)
if pixCoords[0] >= 0 and pixCoords[0] < self.header['NAXIS1'] and \
pixCoords[1] >= 0 and pixCoords[1] < self.header['NAXIS2']:
return True
else:
return False
def getRotationDeg(self):
"""Returns the rotation angle in degrees around the axis, North through
East.
@rtype: float
@return: rotation angle in degrees
"""
return self.WCSStructure.rot
def isFlipped(self):
"""Returns 1 if image is reflected around axis, otherwise returns 0.
@rtype: int
@return: 1 if image is flipped, 0 otherwise
"""
return self.WCSStructure.imflip
def getPixelSizeDeg(self):
"""Returns the pixel scale of the WCS. This is the average of the x, y
pixel scales.
@rtype: float
@return: pixel size in decimal degrees
"""
avSize = (abs(self.WCSStructure.xinc)+abs(self.WCSStructure.yinc))/2.0
return avSize
def getXPixelSizeDeg(self):
"""Returns the pixel scale along the x-axis of the WCS in degrees.
@rtype: float
@return: pixel size in decimal degrees
"""
avSize = abs(self.WCSStructure.xinc)
return avSize
def getYPixelSizeDeg(self):
"""Returns the pixel scale along the y-axis of the WCS in degrees.
@rtype: float
@return: pixel size in decimal degrees
"""
avSize = abs(self.WCSStructure.yinc)
return avSize
def getEquinox(self):
"""Returns the equinox of the WCS.
@rtype: float
@return: equinox of the WCS
"""
return self.WCSStructure.equinox
def getEpoch(self):
"""Returns the epoch of the WCS.
@rtype: float
@return: epoch of the WCS
"""
return self.WCSStructure.epoch
#-----------------------------------------------------------------------------
# Functions for comparing WCS objects
def findWCSOverlap(wcs1, wcs2):
"""Finds the minimum, maximum WCS coords that overlap between wcs1 and
wcs2. Returns these coordinates, plus the corresponding pixel coordinates
for each wcs. Useful for clipping overlapping region between two images.
@rtype: dictionary
@return: dictionary with keys 'overlapWCS' (min, max RA, dec of overlap
between wcs1, wcs2) 'wcs1Pix', 'wcs2Pix' (pixel coords in each input
WCS that correspond to 'overlapWCS' coords)
"""
mm1 = wcs1.getImageMinMaxWCSCoords()
mm2 = wcs2.getImageMinMaxWCSCoords()
overlapWCSCoords = [0.0, 0.0, 0.0, 0.0]
# Note order swapping below is essential
# Min RA
if mm1[0] - mm2[0] <= 0.0:
overlapWCSCoords[0] = mm2[0]
else:
overlapWCSCoords[0] = mm1[0]
# Max RA
if mm1[1] - mm2[1] <= 0.0:
overlapWCSCoords[1] = mm1[1]
else:
overlapWCSCoords[1] = mm2[1]
# Min dec.
if mm1[2] - mm2[2] <= 0.0:
overlapWCSCoords[2] = mm2[2]
else:
overlapWCSCoords[2] = mm1[2]
# Max dec.
if mm1[3] - mm2[3] <= 0.0:
overlapWCSCoords[3] = mm1[3]
else:
overlapWCSCoords[3] = mm2[3]
# Get corresponding pixel coords
p1Low = wcs1.wcs2pix(overlapWCSCoords[0], overlapWCSCoords[2])
p1High = wcs1.wcs2pix(overlapWCSCoords[1], overlapWCSCoords[3])
p1 = [p1Low[0], p1High[0], p1Low[1], p1High[1]]
p2Low = wcs2.wcs2pix(overlapWCSCoords[0], overlapWCSCoords[2])
p2High = wcs2.wcs2pix(overlapWCSCoords[1], overlapWCSCoords[3])
p2 = [p2Low[0], p2High[0], p2Low[1], p2High[1]]
return {'overlapWCS': overlapWCSCoords, 'wcs1Pix': p1, 'wcs2Pix': p2}
#-----------------------------------------------------------------------------
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