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Use faster nearfield_imager in tutorial

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Tammo Jan Dijkema 2020-02-27 10:17:29 +01:00
parent e5fab58b25
commit 806afeba84
2 changed files with 94 additions and 24 deletions
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101
LOFAR LBA imaging tutorial v4.ipynb
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17
lofarimaging/lofarimaging.py
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@ -318,7 +318,7 @@ def sky_imager(visibilities, baselines, freq, npix_l, npix_m):
return img
def ground_imager(visibilities, baselines, freq, npix_p, npix_q, dims, station_pqr, height=1.5):
def ground_imager(visibilities, freq, npix_p, npix_q, dims, station_pqr, height=1.5):
"""Do a Fourier transform for ground imaging"""
img = np.zeros([npix_q, npix_p], dtype=np.complex)
@ -574,7 +574,20 @@ def make_ground_image(xst_filename,
npix_p, npix_q = int(ground_resolution * (extent[1] - extent[0])), int(ground_resolution * (extent[3] - extent[2]))
img = ground_imager(visibilities, baselines, freq, npix_p, npix_q, extent_pqr, station_pqr, height=height)
os.environ["NUMEXPR_NUM_THREADS"] = "3"
# Select a subset of visibilities, only the lower triangular part
baseline_indices = np.tril_indices(visibilities.shape[0])
visibilities_selection = visibilities[baseline_indices]
img = nearfield_imager(visibilities_selection.flatten()[:, np.newaxis],
np.array(baseline_indices).T,
[freq], npix_p, npix_q, extent_pqr, station_pqr, height=height)
# Correct for taking only lower triangular part
img = np.real(2 * img)
img_rotated = ndimage.interpolation.rotate(img, rotation, mode='constant', cval=np.nan)
outer_extent_xyz = extent_from_shapely(*(to_plot_xyz.envelope.bounds)) # Extent in xyz coordinates of the rotated image.