def kernel_plot(kernel, grid_density=150, N=14):
theta_grid = np.linspace(0, np.pi, grid_density)
phi_grid = np.linspace(0, 2 * np.pi, grid_density)
kernel_vals = kernel(sphere.cos_inc_angle(0, 0, theta_grid[:, None], phi_grid), N)
plot.surf_grid_3D(kernel_vals, theta_grid, phi_grid, scale_radius=True)
rotation = np.eye(3)
out_shape = r.shape[:r.ndim - 1]
R = np.asarray(rotation)
Di = np.linalg.inv(R.dot(np.diag(evals)).dot(R.T))
r = r.reshape(-1, 3)
P = np.zeros(len(r))
for (i, u) in enumerate(r):
P[i] = u.T.dot(Di).dot(u)**(3 / 2)
return (1 / (4 * np.pi * np.prod(evals)**(1/2) * P)).reshape(out_shape)
if __name__ == "__main__":
import sphere, coord, plot
npts = 150
theta, phi = sphere.mesh(npts)
xyz = np.dstack(coord.sph2car(theta, phi))
ODF = single_tensor_ODF(xyz, rotation=None)
signal = single_tensor(gradients=xyz,
bvals=1000 * np.ones(npts * npts), rotation=None,
S0=1, SNR=None)
plot.surf_grid_3D(ODF, theta, phi, scale_radius=True)
plot.show()
plot.surf_grid_3D(signal, theta, phi, scale_radius=True)
plot.show()
