y=20e3,
z=2e3,
radius=1.5e3,
props={'magnetization': giutils.ang2vec(1, inc=-70, dec=30)})
]
# Set the inclination and declination of the geomagnetic field.
inc, dec = -10, 13
# Create a regular grid at a constant height
shape = (300, 300)
area = [0, 30e3, 0, 30e3]
x, y, z = gridder.regular(area, shape, z=-10)
fields = [
['Total field Anomaly (nt)',
sphere.tf(x, y, z, model, inc, dec)],
['Bx (nT)', sphere.bx(x, y, z, model)],
['By (nT)', sphere.by(x, y, z, model)],
['Bz (nT)', sphere.bz(x, y, z, model)],
]
# Make maps of all fields calculated
fig = plt.figure(figsize=(7, 6))
plt.rcParams['font.size'] = 10
X, Y = x.reshape(shape) / 1000, y.reshape(shape) / 1000
for i, tmp in enumerate(fields):
ax = plt.subplot(2, 2, i + 1)
field, data = tmp
scale = np.abs([data.min(), data.max()]).max()
ax.set_title(field)
plot = ax.pcolormesh(Y,
from geoist.pfm.giutils import ang2vec, contaminate
from geoist.pfm import sphere
from geoist.pfm.magdir import DipoleMagDir
from geoist.vis import giplt
# Make noise-corrupted synthetic data
inc, dec = -10.0, -15.0 # inclination and declination of the Geomagnetic Field
model = [
geometry.Sphere(3000, 3000, 1000, 1000,
{'magnetization': ang2vec(6.0, -20.0, -10.0)}),
geometry.Sphere(7000, 7000, 1000, 1000,
{'magnetization': ang2vec(10.0, 3.0, -67.0)})
]
area = (0, 10000, 0, 10000)
x, y, z = gridder.scatter(area, 1000, z=-150, seed=0)
tf = contaminate(sphere.tf(x, y, z, model, inc, dec), 5.0, seed=0)
# Give the centers of the dipoles
centers = [[3000, 3000, 1000], [7000, 7000, 1000]]
# Estimate the magnetization vectors
solver = DipoleMagDir(x, y, z, tf, inc, dec, centers).fit()
# Print the estimated and true dipole monents, inclinations and declinations
print('Estimated magnetization (intensity, inclination, declination)')
for e in solver.estimate_:
print(e)
# Plot the fit and the normalized histogram of the residuals
plt.figure(figsize=(14, 5))
plt.subplot(1, 2, 1)