def plot_image_pixels_in_HPX():
header = {'NAXIS': 2,
'CTYPE1': 'RA---HPX',
'CTYPE2': 'DEC--HPX',
}
hpx = WCS(header)
hdulist = get_stripe82_file(301, 2700, 1, 'g', 18)
img = WCS(hdulist[0].header)
origin=0
xpix, ypix = np.meshgrid(*[np.arange(0, hdulist[0].header[key], 30)
for key in ['NAXIS1', 'NAXIS2']])
Xpix = np.vstack(map(np.ravel, (xpix, ypix))).T
Xworld = img.wcs_pix2world(Xpix, origin)
Xhpx = hpx.wcs_world2pix(Xworld, origin)
x, y = Xhpx.T
plt.plot(x, y, '.k')
plt.gca().set_aspect('equal')
plt.xlim(0, 360)
plt.ylim(-90, 90)
plt.show()
def plot_image_pixels_in_HPX():
header = {
'NAXIS': 2,
'CTYPE1': 'RA---HPX',
'CTYPE2': 'DEC--HPX',
}
hpx = WCS(header)
hdulist = get_stripe82_file(301, 2700, 1, 'g', 18)
img = WCS(hdulist[0].header)
origin = 0
xpix, ypix = np.meshgrid(*[
np.arange(0, hdulist[0].header[key], 30)
for key in ['NAXIS1', 'NAXIS2']
])
Xpix = np.vstack(map(np.ravel, (xpix, ypix))).T
Xworld = img.wcs_pix2world(Xpix, origin)
Xhpx = hpx.wcs_world2pix(Xworld, origin)
x, y = Xhpx.T
plt.plot(x, y, '.k')
plt.gca().set_aspect('equal')
plt.xlim(0, 360)
plt.ylim(-90, 90)
plt.show()
def construct_wcs_from_file():
print "Constructing WCS from a FITS file:"
# Construct a wcs instance from file
hdulist = get_stripe82_file(301, 2700, 1, 'g', 18)
wcs = WCS(hdulist[0].header)
# Test a round-trip from pix to world and back
origin = 0
pix_coords = np.arange(1, 11).reshape((5, 2))
world_coords = wcs.wcs_pix2world(pix_coords, origin)
pix_coords2 = wcs.wcs_world2pix(world_coords, origin)
print " - Round trip matches:", np.allclose(pix_coords, pix_coords2)
return wcs
def construct_wcs_from_file():
print "Constructing WCS from a FITS file:"
# Construct a wcs instance from file
hdulist = get_stripe82_file(301, 2700, 1, 'g', 18)
wcs = WCS(hdulist[0].header)
# Test a round-trip from pix to world and back
origin = 0
pix_coords = np.arange(1, 11).reshape((5, 2))
world_coords = wcs.wcs_pix2world(pix_coords, origin)
pix_coords2 = wcs.wcs_world2pix(world_coords, origin)
print " - Round trip matches:", np.allclose(pix_coords, pix_coords2)
return wcs
