/
preset_models.py
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/
preset_models.py
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import os
import numpy as np
from examples.seismic.model import SeismicModel
__all__ = ['demo_model']
def Gardners(vp, normalize=True):
"""
Gardner's relation for vp in km/s
"""
b = 1 / (0.31 * (1e3*vp)**0.25)
if normalize:
b[vp < 1.51] = 1.0
return b
def demo_model(preset, **kwargs):
"""
Utility function to create preset `Model` objects for
demonstration and testing purposes. The particular presets are ::
* `constant-isotropic` : Constant velocity (1.5 km/sec) isotropic model
* `constant-tti` : Constant anisotropic model. Velocity is 1.5 km/sec and
Thomsen parameters are epsilon=.3, delta=.2, theta = .7rad
and phi=.35rad for 3D. 2d/3d is defined from the input shape
* 'layers-isotropic': Simple n-layered model with velocities ranging from 1.5 km/s
to 3.5 km/s in the top and bottom layer respectively.
2d/3d is defined from the input shape
* 'layers-elastic': Simple n-layered model with velocities ranging from 1.5 km/s
to 3.5 km/s in the top and bottom layer respectively.
Vs is set to .5 vp and 0 in the top layer.
* 'layers-viscoelastic': Simple two layers viscoelastic model.
* 'layers-tti': Simple n-layered model with velocities ranging from 1.5 km/s
to 3.5 km/s in the top and bottom layer respectively.
Thomsen parameters in the top layer are 0 and in the lower layers
are scaled versions of vp.
2d/3d is defined from the input shape
* 'circle-isotropic': Simple camembert model with velocities 1.5 km/s
and 2.5 km/s in a circle at the center. 2D only.
* 'marmousi2d-isotropic': Loads the 2D Marmousi data set from the given
filepath. Requires the ``devitocodes/data`` repository
to be available on your machine.
* 'marmousi2d-tti': Loads the 2D Marmousi data set from the given
filepath. Requires the ``devitocodes/data`` repository
to be available on your machine.
* 'marmousi3d-tti': Loads the 2D Marmousi data set from the given
filepath. Requires the ``devitocodes/data`` repository
to be available on your machine.
"""
space_order = kwargs.pop('space_order', 2)
shape = kwargs.pop('shape', (101, 101))
spacing = kwargs.pop('spacing', tuple([10. for _ in shape]))
origin = kwargs.pop('origin', tuple([0. for _ in shape]))
nbl = kwargs.pop('nbl', 10)
dtype = kwargs.pop('dtype', np.float32)
vp = kwargs.pop('vp', 1.5)
nlayers = kwargs.pop('nlayers', 3)
fs = kwargs.pop('fs', False)
density = kwargs.pop('density', False)
if preset.lower() in ['constant-elastic']:
# A constant single-layer model in a 2D or 3D domain
# with velocity 1.5 km/s.
vs = 0.5 * vp
b = 1.0
return SeismicModel(space_order=space_order, vp=vp, vs=vs, b=b,
origin=origin, shape=shape, dtype=dtype, spacing=spacing,
nbl=nbl, **kwargs)
if preset.lower() in ['constant-viscoelastic']:
# A constant single-layer model in a 2D or 3D domain
# with velocity 2.2 km/s.
qp = kwargs.pop('qp', 100.)
vs = kwargs.pop('vs', 1.2)
qs = kwargs.pop('qs', 70.)
b = 1/2.
return SeismicModel(space_order=space_order, vp=vp, qp=qp, vs=vs,
qs=qs, b=b, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl,
**kwargs)
if preset.lower() in ['constant-isotropic']:
# A constant single-layer model in a 2D or 3D domain
# with velocity 1.5 km/s.
if density:
kwargs['b'] = 1
return SeismicModel(space_order=space_order, vp=vp, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, fs=fs, **kwargs)
if preset.lower() in ['constant-viscoacoustic']:
# A constant single-layer model in a 2D or 3D domain
# with velocity 1.5 km/s.
qp = kwargs.pop('qp', 100.)
b = 1/2.
return SeismicModel(space_order=space_order, vp=vp, qp=qp, b=b, nbl=nbl,
dtype=dtype, origin=origin, shape=shape,
spacing=spacing, **kwargs)
elif preset.lower() in ['constant-tti', 'constant-tti-noazimuth']:
# A constant single-layer model in a 2D or 3D domain
# with velocity 1.5 km/s.
epsilon = .3
delta = .2
theta = .7
phi = None
if len(shape) > 2 and preset.lower() not in ['constant-tti-noazimuth']:
phi = .35
if density:
kwargs['b'] = 1
return SeismicModel(space_order=space_order, vp=vp, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, epsilon=epsilon,
delta=delta, theta=theta, phi=phi, bcs="damp", **kwargs)
elif preset.lower() in ['layers-isotropic']:
# A n-layers model in a 2D or 3D domain with two different
# velocities split across the height dimension:
# By default, the top part of the domain has 1.5 km/s,
# and the bottom part of the domain has 2.5 km/s.
vp_top = kwargs.pop('vp_top', 1.5)
vp_bottom = kwargs.pop('vp_bottom', 3.5)
# Define a velocity profile in km/s
v = np.empty(shape, dtype=dtype)
v[:] = vp_top # Top velocity (background)
vp_i = np.linspace(vp_top, vp_bottom, nlayers)
for i in range(1, nlayers):
v[..., i*int(shape[-1] / nlayers):] = vp_i[i] # Bottom velocity
if density:
kwargs['b'] = Gardners(v)
return SeismicModel(space_order=space_order, vp=v, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, bcs="damp",
fs=fs, **kwargs)
elif preset.lower() in ['layers-elastic']:
# A n-layers model in a 2D or 3D domain with two different
# velocities split across the height dimension:
# By default, the top part of the domain has 1.5 km/s,
# and the bottom part of the domain has 2.5 km/s.
vp_top = kwargs.pop('vp_top', 1.5)
vp_bottom = kwargs.pop('vp_bottom', 3.5)
# Define a velocity profile in km/s
v = np.empty(shape, dtype=dtype)
v[:] = vp_top # Top velocity (background)
vp_i = np.linspace(vp_top, vp_bottom, nlayers)
for i in range(1, nlayers):
v[..., i*int(shape[-1] / nlayers):] = vp_i[i] # Bottom velocity
vs = 0.5 * v[:]
b = Gardners(v)
vs[v < 1.51] = 0.0
return SeismicModel(space_order=space_order, vp=v, vs=vs, b=b,
origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, **kwargs)
elif preset.lower() in ['layers-viscoelastic', 'twolayer-viscoelastic',
'2layer-viscoelastic']:
# A two-layer model in a 2D or 3D domain with two different
# velocities split across the height dimension:
# By default, the top part of the domain has 1.6 km/s,
# and the bottom part of the domain has 2.2 km/s.
ratio = kwargs.pop('ratio', 3)
vp_top = kwargs.pop('vp_top', 1.6)
qp_top = kwargs.pop('qp_top', 40.)
vs_top = kwargs.pop('vs_top', 0.4)
qs_top = kwargs.pop('qs_top', 30.)
b_top = kwargs.pop('b_top', 1/1.3)
vp_bottom = kwargs.pop('vp_bottom', 2.2)
qp_bottom = kwargs.pop('qp_bottom', 100.)
vs_bottom = kwargs.pop('vs_bottom', 1.2)
qs_bottom = kwargs.pop('qs_bottom', 70.)
b_bottom = kwargs.pop('b_bottom', 1/2.)
# Define a velocity profile in km/s
vp = np.empty(shape, dtype=dtype)
qp = np.empty(shape, dtype=dtype)
vs = np.empty(shape, dtype=dtype)
qs = np.empty(shape, dtype=dtype)
b = np.empty(shape, dtype=dtype)
# Top and bottom P-wave velocity
vp[:] = vp_top
vp[..., int(shape[-1] / ratio):] = vp_bottom
# Top and bottom P-wave quality factor
qp[:] = qp_top
qp[..., int(shape[-1] / ratio):] = qp_bottom
# Top and bottom S-wave velocity
vs[:] = vs_top
vs[..., int(shape[-1] / ratio):] = vs_bottom
# Top and bottom S-wave quality factor
qs[:] = qs_top
qs[..., int(shape[-1] / ratio):] = qs_bottom
# Top and bottom density
b[:] = b_top
b[..., int(shape[-1] / ratio):] = b_bottom
return SeismicModel(space_order=space_order, vp=vp, qp=qp,
vs=vs, qs=qs, b=b, origin=origin,
shape=shape, dtype=dtype, spacing=spacing,
nbl=nbl, **kwargs)
elif preset.lower() in ['layers-tti', 'layers-tti-noazimuth']:
# A n-layers model in a 2D or 3D domain with two different
# velocities split across the height dimension:
# By default, the top part of the domain has 1.5 km/s,
# and the bottom part of the domain has 2.5 km/s.\
vp_top = kwargs.pop('vp_top', 1.5)
vp_bottom = kwargs.pop('vp_bottom', 3.5)
# Define a velocity profile in km/s
v = np.empty(shape, dtype=dtype)
v[:] = vp_top # Top velocity (background)
vp_i = np.linspace(vp_top, vp_bottom, nlayers)
for i in range(1, nlayers):
v[..., i*int(shape[-1] / nlayers):] = vp_i[i] # Bottom velocity
epsilon = .1*(v - vp_top)
delta = .05*(v - vp_top)
theta = .5*(v - vp_top)
phi = None
if len(shape) > 2 and preset.lower() not in ['layers-tti-noazimuth']:
phi = .25*(v - vp_top)
if density:
kwargs['b'] = Gardners(v)
model = SeismicModel(space_order=space_order, vp=v, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, epsilon=epsilon,
delta=delta, theta=theta, phi=phi, bcs="damp",
fs=fs, **kwargs)
if kwargs.get('smooth', False):
if len(shape) > 2 and preset.lower() not in ['layers-tti-noazimuth']:
model.smooth(('epsilon', 'delta', 'theta', 'phi'))
else:
model.smooth(('epsilon', 'delta', 'theta'))
return model
elif preset.lower() in ['circle-isotropic']:
# A simple circle in a 2D domain with a background velocity.
# By default, the circle velocity is 2.5 km/s,
# and the background veloity is 3.0 km/s.
vp = kwargs.pop('vp_circle', 3.0)
vp_background = kwargs.pop('vp_background', 2.5)
r = kwargs.pop('r', 15)
# Only a 2D preset is available currently
assert(len(shape) == 2)
v = np.empty(shape, dtype=dtype)
v[:] = vp_background
a, b = shape[0] / 2, shape[1] / 2
y, x = np.ogrid[-a:shape[0]-a, -b:shape[1]-b]
v[x*x + y*y <= r*r] = vp
if density:
kwargs['b'] = Gardners(v)
return SeismicModel(space_order=space_order, vp=v, origin=origin, shape=shape,
dtype=dtype, spacing=spacing, nbl=nbl, bcs="damp",
fs=fs, **kwargs)
elif preset.lower() in ['marmousi-isotropic', 'marmousi2d-isotropic']:
shape = (1601, 401)
spacing = (7.5, 7.5)
origin = (0., 0.)
nbl = kwargs.pop('nbl', 20)
# Read 2D Marmousi model from devitocodes/data repo
data_path = kwargs.get('data_path', None)
if data_path is None:
raise ValueError("Path to devitocodes/data not found! Please specify with "
"'data_path=<path/to/devitocodes/data>'")
path = os.path.join(data_path, 'Simple2D/vp_marmousi_bi')
v = np.fromfile(path, dtype='float32', sep="")
v = v.reshape(shape)
# Cut the model to make it slightly cheaper
v = v[301:-300, :]
return SeismicModel(space_order=space_order, vp=v, origin=origin, shape=v.shape,
dtype=np.float32, spacing=spacing, nbl=nbl, bcs="damp",
fs=fs, **kwargs)
elif preset.lower() in ['marmousi-tti2d', 'marmousi2d-tti',
'marmousi-tti3d', 'marmousi3d-tti']:
shape = (201, 201, 70)
nbl = kwargs.pop('nbl', 20)
# Read 2D Marmousi model from devitocodes/data repo
data_path = kwargs.pop('data_path', None)
if data_path is None:
raise ValueError("Path to devitocodes/data not found! Please specify with "
"'data_path=<path/to/devitocodes/data>'")
path = os.path.join(data_path, 'marmousi3D/vp_marmousi_bi')
# velocity
vp = 1e-3 * np.fromfile(os.path.join(data_path, 'marmousi3D/MarmousiVP.raw'),
dtype='float32', sep="")
vp = vp.reshape(shape)
# Epsilon, in % in file, resale between 0 and 1
epsilon = np.fromfile(os.path.join(data_path, 'marmousi3D/MarmousiEps.raw'),
dtype='float32', sep="") * 1e-2
epsilon = epsilon.reshape(shape)
# Delta, in % in file, resale between 0 and 1
delta = np.fromfile(os.path.join(data_path, 'marmousi3D/MarmousiDelta.raw'),
dtype='float32', sep="") * 1e-2
delta = delta.reshape(shape)
# Theta, in degrees in file, resale in radian
theta = np.fromfile(os.path.join(data_path, 'marmousi3D/MarmousiTilt.raw'),
dtype='float32', sep="")
theta = np.float32(np.pi / 180 * theta.reshape(shape))
if preset.lower() in ['marmousi-tti3d', 'marmousi3d-tti']:
# Phi, in degrees in file, resale in radian
phi = np.fromfile(os.path.join(data_path, 'marmousi3D/Azimuth.raw'),
dtype='float32', sep="")
phi = np.float32(np.pi / 180 * phi.reshape(shape))
else:
vp = vp[101, :, :]
epsilon = epsilon[101, :, :]
delta = delta[101, :, :]
theta = theta[101, :, :]
shape = vp.shape
phi = None
spacing = tuple([10.0]*len(shape))
origin = tuple([0.0]*len(shape))
return SeismicModel(space_order=space_order, vp=vp, origin=origin, shape=shape,
dtype=np.float32, spacing=spacing, nbl=nbl, epsilon=epsilon,
delta=delta, theta=theta, phi=phi, bcs="damp", **kwargs)
elif preset.lower() in ['layers-viscoacoustic']:
# A n-layers model in a 2D or 3D domain with two different
# velocities split across the height dimension:
# By default, the top part of the domain has 1.5 km/s,
# and the bottom part of the domain has 3.5 km/s.
# Define a velocity profile in km/s
vp = np.empty(shape, dtype=dtype)
qp = np.empty(shape, dtype=dtype)
# Top and bottom P-wave velocity
vp_top = kwargs.pop('vp_top', 1.5)
vp_bottom = kwargs.pop('vp_bottom', 3.5)
# Define a velocity profile in km/s
vp = np.empty(shape, dtype=dtype)
vp[:] = vp_top # Top velocity (background)
vp_i = np.linspace(vp_top, vp_bottom, nlayers)
for i in range(1, nlayers):
vp[..., i*int(shape[-1] / nlayers):] = vp_i[i] # Bottom velocity
qp[:] = 3.516*((vp[:]*1000.)**2.2)*10**(-6) # Li's empirical formula
b = Gardners(vp, normalize=False)
return SeismicModel(space_order=space_order, vp=vp, qp=qp, b=b, nbl=nbl,
dtype=dtype, origin=origin, shape=shape,
spacing=spacing, **kwargs)
else:
raise ValueError("Unknown model preset name")