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Add option for full-spoke radial trajectory #116

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Add option for full-spoke radial trajectory #116

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22 changes: 16 additions & 6 deletions sigpy/mri/samp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ def poisson(img_shape, accel, calib=(0, 0), dtype=np.complex,
return mask


def radial(coord_shape, img_shape, golden=True, dtype=np.float):
def radial(coord_shape, img_shape, golden=True, half_spoke=True, dtype=np.float32):
"""Generate radial trajectory.

Args:
Expand All @@ -96,6 +96,7 @@ def radial(coord_shape, img_shape, golden=True, dtype=np.float):
and ndim is the number of dimensions.
img_shape (tuple of ints): image shape.
golden (bool): golden angle ordering.
half_spoke (bool): center-out trajectory.
dtype (Dtype): data type.

Returns:
Expand All @@ -119,13 +120,18 @@ def radial(coord_shape, img_shape, golden=True, dtype=np.float):

ntr, nro, ndim = coord_shape
if ndim == 2:
if golden:
if half_spoke:
n, r = np.mgrid[:ntr, :0.5:0.5 / nro]
else:
n, r = np.mgrid[:ntr, -0.5:0.5:1.0 / nro]

if golden and half_spoke:
phi = np.pi * (3 - 5**0.5)
elif golden and not half_spoke:
phi = np.pi * (5**0.5 - 1)*0.5
else:
phi = 2 * np.pi / ntr

n, r = np.mgrid[:ntr, :0.5:0.5 / nro]

theta = n * phi
coord = np.zeros((ntr, nro, 2))
coord[:, :, -1] = r * np.cos(theta)
Expand All @@ -138,9 +144,13 @@ def radial(coord_shape, img_shape, golden=True, dtype=np.float):
else:
raise NotImplementedError

n, r = np.mgrid[:ntr, :0.5:0.5 / nro]
if half_spoke:
n, r = np.mgrid[:ntr, :0.5:0.5 / nro]
beta = np.arccos(2 * ((n * phi1) % 1) - 1)
else:
n, r = np.mgrid[:ntr, -0.5:0.5:1.0 / nro]
beta = np.arccos((n * phi1) % 1)

beta = np.arccos(2 * ((n * phi1) % 1) - 1)
alpha = 2 * np.pi * ((n * phi2) % 1)

coord = np.zeros((ntr, nro, 3))
Expand Down