# Each model element has a dictionary with its physical properties.
# We'll use two spheres with opposite density contrast values.
model = [mesher.Sphere(x=10e3, y=10e3, z=1.5e3, radius=1.5e3,
props={'density': 500}),
mesher.Sphere(x=20e3, y=20e3, z=1.5e3, radius=1.5e3,
props={'density': -500})]
# Create a regular grid at a constant height
shape = (300, 300)
area = [0, 30e3, 0, 30e3]
x, y, z = gridder.regular(area, shape, z=-100)
fields = [
['Gravity (mGal)', sphere.gz(x, y, z, model)],
['gxx (Eotvos)', sphere.gxx(x, y, z, model)],
['gyy (Eotvos)', sphere.gyy(x, y, z, model)],
['gzz (Eotvos)', sphere.gzz(x, y, z, model)],
['gxy (Eotvos)', sphere.gxy(x, y, z, model)],
['gxz (Eotvos)', sphere.gxz(x, y, z, model)],
['gyz (Eotvos)', sphere.gyz(x, y, z, model)],
]
# Make maps of all fields calculated
fig = plt.figure(figsize=(10, 8))
plt.rcParams['font.size'] = 10
X, Y = x.reshape(shape)/1000, y.reshape(shape)/1000
for i, tmp in enumerate(fields):
ax = plt.subplot(3, 3, i + 3)
field, data = tmp
scale = np.abs([data.min(), data.max()]).max()
ax.set_title(field)
def test_gyy():
"gravmag.sphere.gyy python vs cython implementation"
py = _sphere_numpy.gyy(xp, yp, zp, model)
cy = sphere.gyy(xp, yp, zp, model)
diff = np.abs(py - cy)
assert np.all(diff <= precision), 'max diff: %g' % (max(diff))
def test_gyy():
"gravmag.sphere.gyy python vs cython implementation"
py = _sphere_numpy.gyy(xp, yp, zp, model)
cy = sphere.gyy(xp, yp, zp, model)
diff = np.abs(py - cy)
assert np.all(diff <= precision), 'max diff: %g' % (max(diff))
GravMag: Forward modeling of the gravity anomaly and gravity gradient tensor
using model
"""
from fatiando import mesher, gridder
from fatiando.gravmag import sphere
from fatiando.vis import mpl
model = [mesher.Sphere(0, 0, 2000, 1000, {'density': 1000})]
area = (-5000, 5000, -5000, 5000)
shape = (100, 100)
x, y, z = gridder.regular(area, shape, z=-100)
gz = sphere.gz(x, y, z, model)
tensor = [sphere.gxx(x, y, z, model),
sphere.gxy(x, y, z, model),
sphere.gxz(x, y, z, model),
sphere.gyy(x, y, z, model),
sphere.gyz(x, y, z, model),
sphere.gzz(x, y, z, model)]
mpl.figure()
mpl.axis('scaled')
mpl.title('gz')
mpl.contourf(y, x, gz, shape, 15)
mpl.colorbar()
mpl.m2km()
mpl.figure()
titles = ['gxx', 'gxy', 'gxz', 'gyy', 'gyz', 'gzz']
for i, field in enumerate(tensor):
mpl.subplot(2, 3, i + 1)
mpl.axis('scaled')
mpl.title(titles[i])
levels = mpl.contourf(y, x, field, shape, 15)
mesher.Sphere(x=20e3,
y=20e3,
z=1.5e3,
radius=1.5e3,
props={'density': -500})
]
# Create a regular grid at a constant height
shape = (300, 300)
area = [0, 30e3, 0, 30e3]
x, y, z = gridder.regular(area, shape, z=-100)
fields = [
['Gravity (mGal)', sphere.gz(x, y, z, model)],
['gxx (Eotvos)', sphere.gxx(x, y, z, model)],
['gyy (Eotvos)', sphere.gyy(x, y, z, model)],
['gzz (Eotvos)', sphere.gzz(x, y, z, model)],
['gxy (Eotvos)', sphere.gxy(x, y, z, model)],
['gxz (Eotvos)', sphere.gxz(x, y, z, model)],
['gyz (Eotvos)', sphere.gyz(x, y, z, model)],
]
# Make maps of all fields calculated
fig = plt.figure(figsize=(10, 8))
plt.rcParams['font.size'] = 10
X, Y = x.reshape(shape) / 1000, y.reshape(shape) / 1000
for i, tmp in enumerate(fields):
ax = plt.subplot(3, 3, i + 3)
field, data = tmp
scale = np.abs([data.min(), data.max()]).max()
ax.set_title(field)
using model
"""
from fatiando import mesher, gridder
from fatiando.gravmag import sphere
from fatiando.vis import mpl
model = [mesher.Sphere(0, 0, 2000, 1000, {'density': 1000})]
area = (-5000, 5000, -5000, 5000)
shape = (100, 100)
x, y, z = gridder.regular(area, shape, z=-100)
gz = sphere.gz(x, y, z, model)
tensor = [
sphere.gxx(x, y, z, model),
sphere.gxy(x, y, z, model),
sphere.gxz(x, y, z, model),
sphere.gyy(x, y, z, model),
sphere.gyz(x, y, z, model),
sphere.gzz(x, y, z, model)
]
mpl.figure()
mpl.axis('scaled')
mpl.title('gz')
mpl.contourf(y, x, gz, shape, 15)
mpl.colorbar()
mpl.m2km()
mpl.figure()
titles = ['gxx', 'gxy', 'gxz', 'gyy', 'gyz', 'gzz']
for i, field in enumerate(tensor):
mpl.subplot(2, 3, i + 1)
mpl.axis('scaled')
mpl.title(titles[i])
