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