def run_inversion(
m0,
simulation,
data,
actind,
mesh,
maxIter=15,
beta0_ratio=1e0,
coolingFactor=5,
coolingRate=2,
upper=np.inf,
lower=-np.inf,
use_sensitivity_weight=True,
alpha_s=1e-4,
alpha_x=1.0,
alpha_y=1.0,
alpha_z=1.0,
):
"""
Run DC inversion
"""
dmisfit = data_misfit.L2DataMisfit(simulation=simulation, data=data)
# Map for a regularization
regmap = maps.IdentityMap(nP=int(actind.sum()))
# Related to inversion
if use_sensitivity_weight:
reg = regularization.Sparse(mesh, indActive=actind, mapping=regmap)
reg.alpha_s = alpha_s
reg.alpha_x = alpha_x
reg.alpha_y = alpha_y
reg.alpha_z = alpha_z
else:
reg = regularization.Tikhonov(mesh, indActive=actind, mapping=regmap)
reg.alpha_s = alpha_s
reg.alpha_x = alpha_x
reg.alpha_y = alpha_y
reg.alpha_z = alpha_z
opt = optimization.ProjectedGNCG(maxIter=maxIter, upper=upper, lower=lower)
invProb = inverse_problem.BaseInvProblem(dmisfit, reg, opt)
beta = directives.BetaSchedule(coolingFactor=coolingFactor,
coolingRate=coolingRate)
betaest = directives.BetaEstimate_ByEig(beta0_ratio=beta0_ratio)
target = directives.TargetMisfit()
# Need to have basice saving function
update_Jacobi = directives.UpdatePreconditioner()
if use_sensitivity_weight:
updateSensW = directives.UpdateSensitivityWeights()
directiveList = [beta, target, updateSensW, update_Jacobi, betaest]
else:
directiveList = [beta, target, update_Jacobi, betaest]
inv = inversion.BaseInversion(invProb, directiveList=directiveList)
opt.LSshorten = 0.5
opt.remember("xc")
# Run inversion
mopt = inv.run(m0)
return mopt, invProb.dpred
def test_inv_mref_setting(self):
reg1 = regularization.Tikhonov(self.mesh)
reg2 = regularization.Tikhonov(self.mesh)
reg = reg1 + reg2
opt = optimization.ProjectedGNCG(
maxIter=10, lower=-10, upper=10, maxIterLS=20, maxIterCG=50, tolCG=1e-4
)
invProb = inverse_problem.BaseInvProblem(self.dmiscombo, reg, opt)
directives_list = [
directives.ScalingMultipleDataMisfits_ByEig(chi0_ratio=[0.01, 1.0], verbose=True),
directives.AlphasSmoothEstimate_ByEig(verbose=True),
directives.BetaEstimate_ByEig(beta0_ratio=1e-2),
directives.BetaSchedule(),
]
inv = inversion.BaseInversion(invProb, directiveList=directives_list)
m0 = self.model.mean() * np.ones_like(self.model)
mrec = inv.run(m0)
self.assertTrue(np.all(reg1.mref == m0))
self.assertTrue(np.all(reg2.mref == m0))
def setUp(self):
mesh = discretize.TensorMesh([4, 4, 4])
# Magnetic inducing field parameter (A,I,D)
B = [50000, 90, 0]
# Create a MAGsurvey
rx = mag.Point(np.vstack([[0.25, 0.25, 0.25], [-0.25, -0.25, 0.25]]))
srcField = mag.SourceField([rx], parameters=(B[0], B[1], B[2]))
survey = mag.Survey(srcField)
# Create the forward model operator
sim = mag.Simulation3DIntegral(mesh,
survey=survey,
chiMap=maps.IdentityMap(mesh))
# Compute forward model some data
m = np.random.rand(mesh.nC)
data = sim.make_synthetic_data(m, add_noise=True)
reg = regularization.Sparse(mesh)
reg.mref = np.zeros(mesh.nC)
reg.norms = np.c_[0, 1, 1, 1]
reg.eps_p, reg.eps_q = 1e-3, 1e-3
# Data misfit function
dmis = data_misfit.L2DataMisfit(data)
dmis.W = 1.0 / data.relative_error
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=2,
lower=-10.0,
upper=10.0,
maxIterCG=2)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
self.mesh = mesh
self.invProb = invProb
self.sim = sim
# Define the regularization (model objective function)
dc_regularization = regularization.Simple(
mesh,
indActive=ind_active,
mref=starting_conductivity_model,
alpha_s=0.01,
alpha_x=1,
alpha_y=1,
)
# Define how the optimization problem is solved. Here we will use a projected
# Gauss-Newton approach that employs the conjugate gradient solver.
dc_optimization = optimization.ProjectedGNCG(maxIter=5,
lower=-10.0,
upper=2.0,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3)
# Here we define the inverse problem that is to be solved
dc_inverse_problem = inverse_problem.BaseInvProblem(dc_data_misfit,
dc_regularization,
dc_optimization)
#######################################################################
# Define DC Inversion Directives
# ------------------------------
#
# Here we define any directives that are carried out during the inversion. This
# includes the cooling schedule for the trade-off parameter (beta), stopping
# criteria for the inversion and saving inversion results at each iteration.
reg_s.mref = np.zeros(3 * nC)
reg_t = regularization.Sparse(mesh, indActive=actv, mapping=wires.t)
reg_t.mref = np.zeros(3 * nC)
reg = reg_p + reg_s + reg_t
reg.mref = np.zeros(3 * nC)
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=simulation, data=data_object)
dmis.W = 1.0 / data_object.standard_deviation
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=10,
lower=-10,
upper=10.0,
maxIterLS=20,
maxIterCG=20,
tolCG=1e-4)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# A list of directive to control the inverson
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1e1)
# Add sensitivity weights
sensitivity_weights = directives.UpdateSensitivityWeights()
# Here is where the norms are applied
# Use a threshold parameter empirically based on the distribution of
# model parameters
IRLS = directives.Update_IRLS(f_min_change=1e-3,
def run(plotIt=True):
# Define the inducing field parameter
H0 = (50000, 90, 0)
# Create a mesh
dx = 5.0
hxind = [(dx, 5, -1.3), (dx, 10), (dx, 5, 1.3)]
hyind = [(dx, 5, -1.3), (dx, 10), (dx, 5, 1.3)]
hzind = [(dx, 5, -1.3), (dx, 10)]
mesh = TensorMesh([hxind, hyind, hzind], "CCC")
# Get index of the center
midx = int(mesh.nCx / 2)
midy = int(mesh.nCy / 2)
# Lets create a simple Gaussian topo and set the active cells
[xx, yy] = np.meshgrid(mesh.vectorNx, mesh.vectorNy)
zz = -np.exp((xx**2 + yy**2) / 75**2) + mesh.vectorNz[-1]
# We would usually load a topofile
topo = np.c_[utils.mkvc(xx), utils.mkvc(yy), utils.mkvc(zz)]
# Go from topo to array of indices of active cells
actv = utils.surface2ind_topo(mesh, topo, "N")
actv = np.where(actv)[0]
nC = len(actv)
# Create and array of observation points
xr = np.linspace(-20.0, 20.0, 20)
yr = np.linspace(-20.0, 20.0, 20)
X, Y = np.meshgrid(xr, yr)
# Move the observation points 5m above the topo
Z = -np.exp((X**2 + Y**2) / 75**2) + mesh.vectorNz[-1] + 5.0
# Create a MAGsurvey
rxLoc = np.c_[utils.mkvc(X.T), utils.mkvc(Y.T), utils.mkvc(Z.T)]
rxLoc = magnetics.receivers.Point(rxLoc, components=["tmi"])
srcField = magnetics.sources.SourceField(receiver_list=[rxLoc],
parameters=H0)
survey = magnetics.survey.Survey(srcField)
# We can now create a susceptibility model and generate data
# Here a simple block in half-space
model = np.zeros((mesh.nCx, mesh.nCy, mesh.nCz))
model[(midx - 2):(midx + 2), (midy - 2):(midy + 2), -6:-2] = 0.02
model = utils.mkvc(model)
model = model[actv]
# Create active map to go from reduce set to full
actvMap = maps.InjectActiveCells(mesh, actv, -100)
# Create reduced identity map
idenMap = maps.IdentityMap(nP=nC)
# Create the forward model operator
simulation = magnetics.simulation.Simulation3DIntegral(
survey=survey,
mesh=mesh,
chiMap=idenMap,
actInd=actv,
)
# Compute linear forward operator and compute some data
d = simulation.dpred(model)
# Add noise and uncertainties
# We add some random Gaussian noise (1nT)
synthetic_data = d + np.random.randn(len(d))
wd = np.ones(len(synthetic_data)) * 1.0 # Assign flat uncertainties
data_object = data.Data(survey, dobs=synthetic_data, noise_floor=wd)
# Create a regularization
reg = regularization.Sparse(mesh, indActive=actv, mapping=idenMap)
reg.mref = np.zeros(nC)
reg.norms = np.c_[0, 0, 0, 0]
# reg.eps_p, reg.eps_q = 1e-0, 1e-0
# Create sensitivity weights from our linear forward operator
rxLoc = survey.source_field.receiver_list[0].locations
m0 = np.ones(nC) * 1e-4 # Starting model
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=simulation, data=data_object)
dmis.W = 1 / wd
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=20,
lower=0.0,
upper=1.0,
maxIterLS=20,
maxIterCG=20,
tolCG=1e-3)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1e-1)
# Here is where the norms are applied
# Use pick a threshold parameter empirically based on the distribution of
# model parameters
IRLS = directives.Update_IRLS(f_min_change=1e-3, max_irls_iterations=40)
saveDict = directives.SaveOutputEveryIteration(save_txt=False)
update_Jacobi = directives.UpdatePreconditioner()
# Add sensitivity weights
sensitivity_weights = directives.UpdateSensitivityWeights(everyIter=False)
inv = inversion.BaseInversion(
invProb,
directiveList=[
sensitivity_weights, IRLS, betaest, update_Jacobi, saveDict
],
)
# Run the inversion
mrec = inv.run(m0)
if plotIt:
# Here is the recovered susceptibility model
ypanel = midx
zpanel = -5
m_l2 = actvMap * invProb.l2model
m_l2[m_l2 == -100] = np.nan
m_lp = actvMap * mrec
m_lp[m_lp == -100] = np.nan
m_true = actvMap * model
m_true[m_true == -100] = np.nan
# Plot the data
utils.plot_utils.plot2Ddata(rxLoc, d)
plt.figure()
# Plot L2 model
ax = plt.subplot(321)
mesh.plotSlice(
m_l2,
ax=ax,
normal="Z",
ind=zpanel,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCy[ypanel], mesh.vectorCCy[ypanel]]),
color="w",
)
plt.title("Plan l2-model.")
plt.gca().set_aspect("equal")
plt.ylabel("y")
ax.xaxis.set_visible(False)
plt.gca().set_aspect("equal", adjustable="box")
# Vertica section
ax = plt.subplot(322)
mesh.plotSlice(
m_l2,
ax=ax,
normal="Y",
ind=midx,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCz[zpanel], mesh.vectorCCz[zpanel]]),
color="w",
)
plt.title("E-W l2-model.")
plt.gca().set_aspect("equal")
ax.xaxis.set_visible(False)
plt.ylabel("z")
plt.gca().set_aspect("equal", adjustable="box")
# Plot Lp model
ax = plt.subplot(323)
mesh.plotSlice(
m_lp,
ax=ax,
normal="Z",
ind=zpanel,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCy[ypanel], mesh.vectorCCy[ypanel]]),
color="w",
)
plt.title("Plan lp-model.")
plt.gca().set_aspect("equal")
ax.xaxis.set_visible(False)
plt.ylabel("y")
plt.gca().set_aspect("equal", adjustable="box")
# Vertical section
ax = plt.subplot(324)
mesh.plotSlice(
m_lp,
ax=ax,
normal="Y",
ind=midx,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCz[zpanel], mesh.vectorCCz[zpanel]]),
color="w",
)
plt.title("E-W lp-model.")
plt.gca().set_aspect("equal")
ax.xaxis.set_visible(False)
plt.ylabel("z")
plt.gca().set_aspect("equal", adjustable="box")
# Plot True model
ax = plt.subplot(325)
mesh.plotSlice(
m_true,
ax=ax,
normal="Z",
ind=zpanel,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCy[ypanel], mesh.vectorCCy[ypanel]]),
color="w",
)
plt.title("Plan true model.")
plt.gca().set_aspect("equal")
plt.xlabel("x")
plt.ylabel("y")
plt.gca().set_aspect("equal", adjustable="box")
# Vertical section
ax = plt.subplot(326)
mesh.plotSlice(
m_true,
ax=ax,
normal="Y",
ind=midx,
grid=True,
clim=(model.min(), model.max()),
)
plt.plot(
([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
([mesh.vectorCCz[zpanel], mesh.vectorCCz[zpanel]]),
color="w",
)
plt.title("E-W true model.")
plt.gca().set_aspect("equal")
plt.xlabel("x")
plt.ylabel("z")
plt.gca().set_aspect("equal", adjustable="box")
# Plot convergence curves
fig, axs = plt.figure(), plt.subplot()
axs.plot(saveDict.phi_d, "k", lw=2)
axs.plot(
np.r_[IRLS.iterStart, IRLS.iterStart],
np.r_[0, np.max(saveDict.phi_d)],
"k:",
)
twin = axs.twinx()
twin.plot(saveDict.phi_m, "k--", lw=2)
axs.text(
IRLS.iterStart,
0,
"IRLS Steps",
va="bottom",
ha="center",
rotation="vertical",
size=12,
bbox={"facecolor": "white"},
)
axs.set_ylabel("$\phi_d$", size=16, rotation=0)
axs.set_xlabel("Iterations", size=14)
twin.set_ylabel("$\phi_m$", size=16, rotation=0)
mtrue[indx] = -(((1 - t**2.0)**2.0)[indx])
mtrue = np.zeros(mesh.nC)
mtrue[mesh.cell_centers_x > 0.3] = 1.0
mtrue[mesh.cell_centers_x > 0.45] = -0.5
mtrue[mesh.cell_centers_x > 0.6] = 0
# SimPEG problem and survey
prob = simulation.LinearSimulation(mesh, G=G, model_map=maps.IdentityMap())
std = 0.01
survey = prob.make_synthetic_data(mtrue, relative_error=std, add_noise=True)
# Setup the inverse problem
reg = regularization.Tikhonov(mesh, alpha_s=1.0, alpha_x=1.0)
dmis = data_misfit.L2DataMisfit(data=survey, simulation=prob)
opt = optimization.ProjectedGNCG(maxIter=10, maxIterCG=50, tolCG=1e-4)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
directiveslist = [
directives.BetaEstimate_ByEig(beta0_ratio=1e-5),
directives.BetaSchedule(coolingFactor=10.0, coolingRate=2),
directives.TargetMisfit(),
]
inv = inversion.BaseInversion(invProb, directiveList=directiveslist)
m0 = np.zeros_like(mtrue)
mnormal = inv.run(m0)
#########################################
# Petrophysically constrained inversion #
#########################################
def setup_and_run_std_inv(mesh, dc_survey, dc_data, std_dc, conductivity_map,
ind_active, starting_conductivity_model):
"""Code to setup and run a standard inversion.
Parameters
----------
mesh : TYPE
DESCRIPTION.
dc_survey : TYPE
DESCRIPTION.
dc_data : TYPE
DESCRIPTION.
std_dc : TYPE
DESCRIPTION.
conductivity_map : TYPE
DESCRIPTION.
ind_active : TYPE
DESCRIPTION.
starting_conductivity_model : TYPE
DESCRIPTION.
Returns
-------
save_iteration : TYPE
DESCRIPTION.
save_dict_iteration : TYPE
DESCRIPTION.
"""
# Add standard deviations to data object
dc_data.standard_deviation = std_dc
# Define the simulation (physics of the problem)
dc_simulation = dc.simulation_2d.Simulation2DNodal(
mesh, survey=dc_survey, sigmaMap=conductivity_map, Solver=Solver)
# Define the data misfit.
dc_data_misfit = data_misfit.L2DataMisfit(data=dc_data,
simulation=dc_simulation)
# Define the regularization (model objective function)
dc_regularization = regularization.Simple(mesh,
indActive=ind_active,
mref=starting_conductivity_model,
alpha_s=0.01,
alpha_x=1,
alpha_y=1)
# Define how the optimization problem is solved. Here we will use a
# projected. Gauss-Newton approach that employs the conjugate gradient
# solver.
dc_optimization = optimization.ProjectedGNCG(maxIter=15,
lower=-np.inf,
upper=np.inf,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3)
# Here we define the inverse problem that is to be solved
dc_inverse_problem = inverse_problem.BaseInvProblem(
dc_data_misfit, dc_regularization, dc_optimization)
# Define inversion directives
# Apply and update sensitivity weighting as the model updates
update_sensitivity_weighting = directives.UpdateSensitivityWeights()
# Defining a starting value for the trade-off parameter (beta) between the
# data misfit and the regularization.
starting_beta = directives.BetaEstimate_ByEig(beta0_ratio=1e2)
# Set the rate of reduction in trade-off parameter (beta) each time the
# the inverse problem is solved. And set the number of Gauss-Newton
# iterations for each trade-off paramter value.
beta_schedule = directives.BetaSchedule(coolingFactor=10, coolingRate=1)
# Options for outputting recovered models and predicted data for each beta.
save_iteration = directives.SaveOutputEveryIteration(save_txt=False)
# save results from each iteration in a dict
save_dict_iteration = directives.SaveOutputDictEveryIteration(
saveOnDisk=False)
directives_list = [
update_sensitivity_weighting,
starting_beta,
beta_schedule,
save_iteration,
save_dict_iteration,
]
# Here we combine the inverse problem and the set of directives
dc_inversion = inversion.BaseInversion(dc_inverse_problem,
directiveList=directives_list)
# Run inversion
_ = dc_inversion.run(starting_conductivity_model)
return save_iteration, save_dict_iteration
def run_inversion(
m0,
survey,
actind,
mesh,
wires,
std,
eps,
maxIter=15,
beta0_ratio=1e0,
coolingFactor=2,
coolingRate=2,
maxIterLS=20,
maxIterCG=10,
LSshorten=0.5,
eta_lower=1e-5,
eta_upper=1,
tau_lower=1e-6,
tau_upper=10.0,
c_lower=1e-2,
c_upper=1.0,
is_log_tau=True,
is_log_c=True,
is_log_eta=True,
mref=None,
alpha_s=1e-4,
alpha_x=1e0,
alpha_y=1e0,
alpha_z=1e0,
):
"""
Run Spectral Spectral IP inversion
"""
dmisfit = data_misfit.L2DataMisfit(survey)
uncert = abs(survey.dobs) * std + eps
dmisfit.W = 1.0 / uncert
# Map for a regularization
# Related to inversion
# Set Upper and Lower bounds
e = np.ones(actind.sum())
if np.isscalar(eta_lower):
eta_lower = e * eta_lower
if np.isscalar(tau_lower):
tau_lower = e * tau_lower
if np.isscalar(c_lower):
c_lower = e * c_lower
if np.isscalar(eta_upper):
eta_upper = e * eta_upper
if np.isscalar(tau_upper):
tau_upper = e * tau_upper
if np.isscalar(c_upper):
c_upper = e * c_upper
if is_log_eta:
eta_upper = np.log(eta_upper)
eta_lower = np.log(eta_lower)
if is_log_tau:
tau_upper = np.log(tau_upper)
tau_lower = np.log(tau_lower)
if is_log_c:
c_upper = np.log(c_upper)
c_lower = np.log(c_lower)
m_upper = np.r_[eta_upper, tau_upper, c_upper]
m_lower = np.r_[eta_lower, tau_lower, c_lower]
# Set up regularization
reg_eta = regularization.Simple(mesh, mapping=wires.eta, indActive=actind)
reg_tau = regularization.Simple(mesh, mapping=wires.tau, indActive=actind)
reg_c = regularization.Simple(mesh, mapping=wires.c, indActive=actind)
# Todo:
reg_eta.alpha_s = alpha_s
reg_tau.alpha_s = 0.0
reg_c.alpha_s = 0.0
reg_eta.alpha_x = alpha_x
reg_tau.alpha_x = alpha_x
reg_c.alpha_x = alpha_x
reg_eta.alpha_y = alpha_y
reg_tau.alpha_y = alpha_y
reg_c.alpha_y = alpha_y
reg_eta.alpha_z = alpha_z
reg_tau.alpha_z = alpha_z
reg_c.alpha_z = alpha_z
reg = reg_eta + reg_tau + reg_c
# Use Projected Gauss Newton scheme
opt = optimization.ProjectedGNCG(
maxIter=maxIter,
upper=m_upper,
lower=m_lower,
maxIterLS=maxIterLS,
maxIterCG=maxIterCG,
LSshorten=LSshorten,
)
invProb = inverse_problem.BaseInvProblem(dmisfit, reg, opt)
beta = directives.BetaSchedule(coolingFactor=coolingFactor, coolingRate=coolingRate)
betaest = directives.BetaEstimate_ByEig(beta0_ratio=beta0_ratio)
target = directives.TargetMisfit()
directiveList = [beta, betaest, target]
inv = inversion.BaseInversion(invProb, directiveList=directiveList)
opt.LSshorten = 0.5
opt.remember("xc")
# Run inversion
mopt = inv.run(m0)
return mopt, invProb.dpred
# Define the regularization (model objective function)
ip_regularization = regularization.Simple(
mesh,
indActive=ind_active,
mapping=maps.IdentityMap(nP=nC),
alpha_s=0.01,
alpha_x=1,
alpha_y=1,
alpha_z=1,
)
# Define how the optimization problem is solved.
ip_optimization = optimization.ProjectedGNCG(maxIter=15,
lower=0.0,
upper=10,
maxIterCG=30,
tolCG=1e-2)
# Here we define the inverse problem that is to be solved
ip_inverse_problem = inverse_problem.BaseInvProblem(ip_data_misfit,
ip_regularization,
ip_optimization)
#######################################################
# Define IP Inversion Directives
# ------------------------------
#
# Here we define the directives in the same manner as the DC inverse problem.
#
def test_basic_inversion(self):
"""
Test to see if inversion recovers model
"""
h = [(2, 30)]
meshObj = discretize.TensorMesh((h, h, [(2, 10)]), x0="CCN")
mod = 0.00025 * np.ones(meshObj.nC)
mod[(meshObj.gridCC[:, 0] > -4.0)
& (meshObj.gridCC[:, 1] > -4.0)
& (meshObj.gridCC[:, 0] < 4.0)
& (meshObj.gridCC[:, 1] < 4.0)] = 0.001
times = np.logspace(-4, -2, 5)
waveObj = vrm.waveforms.SquarePulse(delt=0.02)
x, y = np.meshgrid(np.linspace(-17, 17, 16), np.linspace(-17, 17, 16))
x, y, z = mkvc(x), mkvc(y), 0.5 * np.ones(np.size(x))
receiver_list = [
vrm.Rx.Point(np.c_[x, y, z],
times=times,
fieldType="dbdt",
orientation="z")
]
txNodes = np.array([
[-20, -20, 0.001],
[20, -20, 0.001],
[20, 20, 0.001],
[-20, 20, 0.01],
[-20, -20, 0.001],
])
txList = [vrm.Src.LineCurrent(receiver_list, txNodes, 1.0, waveObj)]
Survey = vrm.Survey(txList)
Survey.t_active = np.zeros(Survey.nD, dtype=bool)
Survey.set_active_interval(-1e6, 1e6)
Problem = vrm.Simulation3DLinear(meshObj,
survey=Survey,
refinement_factor=2)
dobs = Problem.make_synthetic_data(mod)
Survey.noise_floor = 1e-11
dmis = data_misfit.L2DataMisfit(data=dobs, simulation=Problem)
W = mkvc((np.sum(np.array(Problem.A)**2, axis=0)))**0.25
reg = regularization.Simple(meshObj,
alpha_s=0.01,
alpha_x=1.0,
alpha_y=1.0,
alpha_z=1.0,
cell_weights=W)
opt = optimization.ProjectedGNCG(maxIter=20,
lower=0.0,
upper=1e-2,
maxIterLS=20,
tolCG=1e-4)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
directives = [
BetaSchedule(coolingFactor=2, coolingRate=1),
TargetMisfit()
]
inv = inversion.BaseInversion(invProb, directiveList=directives)
m0 = 1e-6 * np.ones(len(mod))
mrec = inv.run(m0)
dmis_final = np.sum(
(dmis.W.diagonal() * (mkvc(dobs) - Problem.fields(mrec)))**2)
mod_err_2 = np.sqrt(np.sum((mrec - mod)**2)) / np.size(mod)
mod_err_inf = np.max(np.abs(mrec - mod))
self.assertTrue(dmis_final < Survey.nD and mod_err_2 < 5e-6
and mod_err_inf < np.max(mod))
store_sensitivities="ram")
wr = simulation.getJtJdiag(mstart)**0.5
wr = wr / np.max(np.abs(wr))
# Create a regularization function, in this case l2l2
reg = regularization.Sparse(mesh,
indActive=surf,
mapping=maps.IdentityMap(nP=nC),
alpha_z=0)
reg.mref = np.zeros(nC)
# Specify how the optimization will proceed, set susceptibility bounds to inf
opt = optimization.ProjectedGNCG(maxIter=20,
lower=-np.inf,
upper=np.inf,
maxIterLS=20,
maxIterCG=20,
tolCG=1e-3)
# Define misfit function (obs-calc)
dmis = data_misfit.L2DataMisfit(simulation=simulation, data=data_object)
# Create the default L2 inverse problem from the above objects
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# Specify how the initial beta is found
betaest = directives.BetaEstimate_ByEig(beta0_ratio=2)
# Target misfit to stop the inversion,
# try to fit as much as possible of the signal, we don't want to lose anything
IRLS = directives.Update_IRLS(f_min_change=1e-3,
W = utils.sdiag(wr)
reg_simple = utils.make_SimplePGIwithRelationships_regularization(
mesh=mesh,
gmmref=clfmapping,
gmm=clfmapping,
approx_gradient=True,
alpha_x=1.0,
wiresmap=wires,
cell_weights_list=[wr1, wr2],
)
opt = optimization.ProjectedGNCG(
maxIter=30,
tolX=1e-6,
maxIterCG=100,
tolCG=1e-3,
lower=-10,
upper=10,
)
invProb = inverse_problem.BaseInvProblem(dmis, reg_simple, opt)
# directives
scales = directives.ScalingMultipleDataMisfits_ByEig(chi0_ratio=np.r_[1.0,
1.0],
verbose=True,
n_pw_iter=10)
scaling_schedule = directives.JointScalingSchedule(verbose=True)
alpha0_ratio = np.r_[np.zeros(len(reg_simple.objfcts[0].objfcts)),
100.0 * np.ones(len(reg_simple.objfcts[1].objfcts)),
1.0 * np.ones(len(reg_simple.objfcts[2].objfcts)), ]
def setUp(self):
np.random.seed(0)
H0 = (50000.0, 90.0, 0.0)
# The magnetization is set along a different
# direction (induced + remanence)
M = np.array([45.0, 90.0])
# Create grid of points for topography
# Lets create a simple Gaussian topo
# and set the active cells
[xx, yy] = np.meshgrid(np.linspace(-200, 200, 50),
np.linspace(-200, 200, 50))
b = 100
A = 50
zz = A * np.exp(-0.5 * ((xx / b)**2.0 + (yy / b)**2.0))
# We would usually load a topofile
topo = np.c_[utils.mkvc(xx), utils.mkvc(yy), utils.mkvc(zz)]
# Create and array of observation points
xr = np.linspace(-100.0, 100.0, 20)
yr = np.linspace(-100.0, 100.0, 20)
X, Y = np.meshgrid(xr, yr)
Z = A * np.exp(-0.5 * ((X / b)**2.0 + (Y / b)**2.0)) + 5
# Create a MAGsurvey
xyzLoc = np.c_[utils.mkvc(X.T), utils.mkvc(Y.T), utils.mkvc(Z.T)]
rxLoc = mag.Point(xyzLoc)
srcField = mag.SourceField([rxLoc], parameters=H0)
survey = mag.Survey(srcField)
# Create a mesh
h = [5, 5, 5]
padDist = np.ones((3, 2)) * 100
mesh = mesh_builder_xyz(xyzLoc,
h,
padding_distance=padDist,
depth_core=100,
mesh_type="tree")
mesh = refine_tree_xyz(mesh,
topo,
method="surface",
octree_levels=[4, 4],
finalize=True)
self.mesh = mesh
# Define an active cells from topo
actv = utils.surface2ind_topo(mesh, topo)
nC = int(actv.sum())
model = np.zeros((mesh.nC, 3))
# Convert the inclination declination to vector in Cartesian
M_xyz = utils.mat_utils.dip_azimuth2cartesian(M[0], M[1])
# Get the indicies of the magnetized block
ind = utils.model_builder.getIndicesBlock(
np.r_[-20, -20, -10],
np.r_[20, 20, 25],
mesh.gridCC,
)[0]
# Assign magnetization values
model[ind, :] = np.kron(np.ones((ind.shape[0], 1)), M_xyz * 0.05)
# Remove air cells
self.model = model[actv, :]
# Create active map to go from reduce set to full
self.actvMap = maps.InjectActiveCells(mesh, actv, np.nan)
# Creat reduced identity map
idenMap = maps.IdentityMap(nP=nC * 3)
# Create the forward model operator
sim = mag.Simulation3DIntegral(
self.mesh,
survey=survey,
model_type="vector",
chiMap=idenMap,
actInd=actv,
store_sensitivities="disk",
)
self.sim = sim
# Compute some data and add some random noise
data = sim.make_synthetic_data(utils.mkvc(self.model),
relative_error=0.0,
noise_floor=5.0,
add_noise=True)
# This Mapping connects the regularizations for the three-component
# vector model
wires = maps.Wires(("p", nC), ("s", nC), ("t", nC))
# Create three regularization for the different components
# of magnetization
reg_p = regularization.Sparse(mesh, indActive=actv, mapping=wires.p)
reg_p.mref = np.zeros(3 * nC)
reg_s = regularization.Sparse(mesh, indActive=actv, mapping=wires.s)
reg_s.mref = np.zeros(3 * nC)
reg_t = regularization.Sparse(mesh, indActive=actv, mapping=wires.t)
reg_t.mref = np.zeros(3 * nC)
reg = reg_p + reg_s + reg_t
reg.mref = np.zeros(3 * nC)
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=sim, data=data)
# dmis.W = 1./survey.std
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=10,
lower=-10,
upper=10.0,
maxIterLS=5,
maxIterCG=5,
tolCG=1e-4)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# A list of directive to control the inverson
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1e1)
# Here is where the norms are applied
# Use pick a treshold parameter empirically based on the distribution of
# model parameters
IRLS = directives.Update_IRLS(f_min_change=1e-3,
max_irls_iterations=0,
beta_tol=5e-1)
# Pre-conditioner
update_Jacobi = directives.UpdatePreconditioner()
sensitivity_weights = directives.UpdateSensitivityWeights(
everyIter=False)
inv = inversion.BaseInversion(
invProb,
directiveList=[sensitivity_weights, IRLS, update_Jacobi, betaest])
# Run the inversion
m0 = np.ones(3 * nC) * 1e-4 # Starting model
mrec_MVIC = inv.run(m0)
sim.chiMap = maps.SphericalSystem(nP=nC * 3)
self.mstart = sim.chiMap.inverse(mrec_MVIC)
dmis.simulation.model = self.mstart
beta = invProb.beta
# Create a block diagonal regularization
wires = maps.Wires(("amp", nC), ("theta", nC), ("phi", nC))
# Create a Combo Regularization
# Regularize the amplitude of the vectors
reg_a = regularization.Sparse(mesh, indActive=actv, mapping=wires.amp)
reg_a.norms = np.c_[0.0, 0.0, 0.0,
0.0] # Sparse on the model and its gradients
reg_a.mref = np.zeros(3 * nC)
# Regularize the vertical angle of the vectors
reg_t = regularization.Sparse(mesh,
indActive=actv,
mapping=wires.theta)
reg_t.alpha_s = 0.0 # No reference angle
reg_t.space = "spherical"
reg_t.norms = np.c_[2.0, 0.0, 0.0, 0.0] # Only norm on gradients used
# Regularize the horizontal angle of the vectors
reg_p = regularization.Sparse(mesh, indActive=actv, mapping=wires.phi)
reg_p.alpha_s = 0.0 # No reference angle
reg_p.space = "spherical"
reg_p.norms = np.c_[2.0, 0.0, 0.0, 0.0] # Only norm on gradients used
reg = reg_a + reg_t + reg_p
reg.mref = np.zeros(3 * nC)
Lbound = np.kron(np.asarray([0, -np.inf, -np.inf]), np.ones(nC))
Ubound = np.kron(np.asarray([10, np.inf, np.inf]), np.ones(nC))
# Add directives to the inversion
opt = optimization.ProjectedGNCG(
maxIter=5,
lower=Lbound,
upper=Ubound,
maxIterLS=5,
maxIterCG=5,
tolCG=1e-3,
stepOffBoundsFact=1e-3,
)
opt.approxHinv = None
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt, beta=beta)
# Here is where the norms are applied
IRLS = directives.Update_IRLS(
f_min_change=1e-4,
max_irls_iterations=5,
minGNiter=1,
beta_tol=0.5,
coolingRate=1,
coolEps_q=True,
sphericalDomain=True,
)
# Special directive specific to the mag amplitude problem. The sensitivity
# weights are update between each iteration.
ProjSpherical = directives.ProjectSphericalBounds()
sensitivity_weights = directives.UpdateSensitivityWeights()
update_Jacobi = directives.UpdatePreconditioner()
self.inv = inversion.BaseInversion(
invProb,
directiveList=[
ProjSpherical, IRLS, sensitivity_weights, update_Jacobi
],
)
def run_inversion(
self,
maxIter=60,
m0=0.0,
mref=0.0,
percentage=5,
floor=0.1,
chifact=1,
beta0_ratio=1.0,
coolingFactor=1,
n_iter_per_beta=1,
alpha_s=1.0,
alpha_x=1.0,
alpha_z=1.0,
use_target=False,
use_tikhonov=True,
use_irls=False,
p_s=2,
p_x=2,
p_y=2,
p_z=2,
beta_start=None,
):
self.uncertainty = percentage * abs(self.data_prop.dobs) * 0.01 + floor
m0 = np.ones(self.mesh_prop.nC) * m0
mref = np.ones(self.mesh_prop.nC) * mref
if ~use_tikhonov:
reg = regularization.Sparse(
self.mesh_prop,
alpha_s=alpha_s,
alpha_x=alpha_x,
alpha_y=alpha_z,
mref=mref,
mapping=maps.IdentityMap(self.mesh_prop),
cell_weights=self.mesh_prop.vol,
)
else:
reg = regularization.Tikhonov(
self.mesh_prop,
alpha_s=alpha_s,
alpha_x=alpha_x,
alpha_y=alpha_z,
mref=mref,
mapping=maps.IdentityMap(self.mesh_prop),
)
dataObj = data.Data(self.survey_prop,
dobs=self.dobs,
noise_floor=self.uncertainty)
dmis = data_misfit.L2DataMisfit(simulation=self.simulation_prop,
data=dataObj)
dmis.W = 1.0 / self.uncertainty
opt = optimization.ProjectedGNCG(maxIter=maxIter, maxIterCG=20)
opt.lower = 0.0
opt.remember("xc")
opt.tolG = 1e-10
opt.eps = 1e-10
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
beta_schedule = directives.BetaSchedule(coolingFactor=coolingFactor,
coolingRate=n_iter_per_beta)
save = directives.SaveOutputEveryIteration()
print(chifact)
if use_irls:
IRLS = directives.Update_IRLS(
f_min_change=1e-4,
minGNiter=1,
silent=False,
max_irls_iterations=40,
beta_tol=5e-1,
coolEpsFact=1.3,
chifact_start=chifact,
)
if beta_start is None:
directives_list = [
directives.BetaEstimate_ByEig(beta0_ratio=beta0_ratio),
IRLS,
save,
]
else:
directives_list = [IRLS, save]
invProb.beta = beta_start
reg.norms = np.c_[p_s, p_x, p_z, 2]
else:
target = directives.TargetMisfit(chifact=chifact)
directives_list = [
directives.BetaEstimate_ByEig(beta0_ratio=beta0_ratio),
beta_schedule,
save,
]
if use_target:
directives_list.append(target)
inv = inversion.BaseInversion(invProb, directiveList=directives_list)
mopt = inv.run(m0)
model = opt.recall("xc")
model.append(mopt)
pred = []
for m in model:
pred.append(self.simulation_prop.dpred(m))
return model, pred, save
def run(plotIt=True, cleanAfterRun=True):
# Start by downloading files from the remote repository
# directory where the downloaded files are
url = "https://storage.googleapis.com/simpeg/Chile_GRAV_4_Miller/Chile_GRAV_4_Miller.tar.gz"
downloads = download(url, overwrite=True)
basePath = downloads.split(".")[0]
# unzip the tarfile
tar = tarfile.open(downloads, "r")
tar.extractall()
tar.close()
input_file = basePath + os.path.sep + "LdM_input_file.inp"
# %% User input
# Plotting parameters, max and min densities in g/cc
vmin = -0.6
vmax = 0.6
# weight exponent for default weighting
wgtexp = 3.0
# %%
# Read in the input file which included all parameters at once
# (mesh, topo, model, survey, inv param, etc.)
driver = GravityDriver_Inv(input_file)
# %%
# Now we need to create the survey and model information.
# Access the mesh and survey information
mesh = driver.mesh #
survey = driver.survey
data_object = driver.data
# [survey, data_object] = driver.survey
# define gravity survey locations
rxLoc = survey.source_field.receiver_list[0].locations
# define gravity data and errors
d = data_object.dobs
# Get the active cells
active = driver.activeCells
nC = len(active) # Number of active cells
# Create active map to go from reduce set to full
activeMap = maps.InjectActiveCells(mesh, active, -100)
# Create static map
static = driver.staticCells
dynamic = driver.dynamicCells
staticCells = maps.InjectActiveCells(None,
dynamic,
driver.m0[static],
nC=nC)
mstart = driver.m0[dynamic]
# Get index of the center
midx = int(mesh.nCx / 2)
# %%
# Now that we have a model and a survey we can build the linear system ...
# Create the forward model operator
simulation = gravity.simulation.Simulation3DIntegral(survey=survey,
mesh=mesh,
rhoMap=staticCells,
actInd=active)
# %% Create inversion objects
reg = regularization.Sparse(mesh,
indActive=active,
mapping=staticCells,
gradientType="total")
reg.mref = driver.mref[dynamic]
reg.norms = np.c_[0.0, 1.0, 1.0, 1.0]
# reg.norms = driver.lpnorms
# Specify how the optimization will proceed
opt = optimization.ProjectedGNCG(
maxIter=20,
lower=driver.bounds[0],
upper=driver.bounds[1],
maxIterLS=10,
maxIterCG=20,
tolCG=1e-4,
)
# Define misfit function (obs-calc)
dmis = data_misfit.L2DataMisfit(data=data_object, simulation=simulation)
# create the default L2 inverse problem from the above objects
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# Specify how the initial beta is found
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1e-2)
# IRLS sets up the Lp inversion problem
# Set the eps parameter parameter in Line 11 of the
# input file based on the distribution of model (DEFAULT = 95th %ile)
IRLS = directives.Update_IRLS(f_min_change=1e-4,
max_irls_iterations=40,
coolEpsFact=1.5,
beta_tol=5e-1)
# Preconditioning refreshing for each IRLS iteration
update_Jacobi = directives.UpdatePreconditioner()
sensitivity_weights = directives.UpdateSensitivityWeights()
# Create combined the L2 and Lp problem
inv = inversion.BaseInversion(
invProb,
directiveList=[sensitivity_weights, IRLS, update_Jacobi, betaest])
# %%
# Run L2 and Lp inversion
mrec = inv.run(mstart)
if cleanAfterRun:
os.remove(downloads)
shutil.rmtree(basePath)
# %%
if plotIt:
# Plot observed data
# The sign of the data is flipped here for the change of convention
# between Cartesian coordinate system (internal SimPEG format that
# expects "positive up" gravity signal) and traditional gravity data
# conventions (positive down). For example a traditional negative
# gravity anomaly is described as "positive up" in Cartesian coordinates
# and hence the sign needs to be flipped for use in SimPEG.
plot2Ddata(rxLoc, -d)
# %%
# Write output model and data files and print misfit stats.
# reconstructing l2 model mesh with air cells and active dynamic cells
L2out = activeMap * invProb.l2model
# reconstructing lp model mesh with air cells and active dynamic cells
Lpout = activeMap * mrec
# %%
# Plot out sections and histograms of the smooth l2 model.
# The ind= parameter is the slice of the model from top down.
yslice = midx + 1
L2out[L2out == -100] = np.nan # set "air" to nan
plt.figure(figsize=(10, 7))
plt.suptitle("Smooth Inversion: Depth weight = " + str(wgtexp))
ax = plt.subplot(221)
dat1 = mesh.plotSlice(
L2out,
ax=ax,
normal="Z",
ind=-16,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.plot(
np.array([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
np.array([mesh.vectorCCy[yslice], mesh.vectorCCy[yslice]]),
c="gray",
linestyle="--",
)
plt.scatter(rxLoc[0:, 0], rxLoc[0:, 1], color="k", s=1)
plt.title("Z: " + str(mesh.vectorCCz[-16]) + " m")
plt.xlabel("Easting (m)")
plt.ylabel("Northing (m)")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(dat1[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4))
cb.set_label("Density (g/cc$^3$)")
ax = plt.subplot(222)
dat = mesh.plotSlice(
L2out,
ax=ax,
normal="Z",
ind=-27,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.plot(
np.array([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
np.array([mesh.vectorCCy[yslice], mesh.vectorCCy[yslice]]),
c="gray",
linestyle="--",
)
plt.scatter(rxLoc[0:, 0], rxLoc[0:, 1], color="k", s=1)
plt.title("Z: " + str(mesh.vectorCCz[-27]) + " m")
plt.xlabel("Easting (m)")
plt.ylabel("Northing (m)")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(dat1[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4))
cb.set_label("Density (g/cc$^3$)")
ax = plt.subplot(212)
mesh.plotSlice(
L2out,
ax=ax,
normal="Y",
ind=yslice,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.title("Cross Section")
plt.xlabel("Easting(m)")
plt.ylabel("Elevation")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(
dat1[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4),
cmap="bwr",
)
cb.set_label("Density (g/cc$^3$)")
# %%
# Make plots of Lp model
yslice = midx + 1
Lpout[Lpout == -100] = np.nan # set "air" to nan
plt.figure(figsize=(10, 7))
plt.suptitle("Compact Inversion: Depth weight = " + str(wgtexp) +
": $\epsilon_p$ = " + str(round(reg.eps_p, 1)) +
": $\epsilon_q$ = " + str(round(reg.eps_q, 2)))
ax = plt.subplot(221)
dat = mesh.plotSlice(
Lpout,
ax=ax,
normal="Z",
ind=-16,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.plot(
np.array([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
np.array([mesh.vectorCCy[yslice], mesh.vectorCCy[yslice]]),
c="gray",
linestyle="--",
)
plt.scatter(rxLoc[0:, 0], rxLoc[0:, 1], color="k", s=1)
plt.title("Z: " + str(mesh.vectorCCz[-16]) + " m")
plt.xlabel("Easting (m)")
plt.ylabel("Northing (m)")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(dat[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4))
cb.set_label("Density (g/cc$^3$)")
ax = plt.subplot(222)
dat = mesh.plotSlice(
Lpout,
ax=ax,
normal="Z",
ind=-27,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.plot(
np.array([mesh.vectorCCx[0], mesh.vectorCCx[-1]]),
np.array([mesh.vectorCCy[yslice], mesh.vectorCCy[yslice]]),
c="gray",
linestyle="--",
)
plt.scatter(rxLoc[0:, 0], rxLoc[0:, 1], color="k", s=1)
plt.title("Z: " + str(mesh.vectorCCz[-27]) + " m")
plt.xlabel("Easting (m)")
plt.ylabel("Northing (m)")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(dat[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4))
cb.set_label("Density (g/cc$^3$)")
ax = plt.subplot(212)
dat = mesh.plotSlice(
Lpout,
ax=ax,
normal="Y",
ind=yslice,
clim=(vmin, vmax),
pcolorOpts={"cmap": "bwr"},
)
plt.title("Cross Section")
plt.xlabel("Easting (m)")
plt.ylabel("Elevation (m)")
plt.gca().set_aspect("equal", adjustable="box")
cb = plt.colorbar(dat[0],
orientation="vertical",
ticks=np.linspace(vmin, vmax, 4))
cb.set_label("Density (g/cc$^3$)")
def setUp(self):
# We will assume a vertical inducing field
H0 = (50000.0, 90.0, 0.0)
# The magnetization is set along a different direction (induced + remanence)
M = np.array([45.0, 90.0])
# Block with an effective susceptibility
chi_e = 0.05
# Create grid of points for topography
# Lets create a simple Gaussian topo and set the active cells
[xx, yy] = np.meshgrid(np.linspace(-200, 200, 50),
np.linspace(-200, 200, 50))
b = 100
A = 50
zz = A * np.exp(-0.5 * ((xx / b)**2.0 + (yy / b)**2.0))
topo = np.c_[mkvc(xx), mkvc(yy), mkvc(zz)]
# Create an array of observation points
xr = np.linspace(-100.0, 100.0, 20)
yr = np.linspace(-100.0, 100.0, 20)
X, Y = np.meshgrid(xr, yr)
Z = A * np.exp(-0.5 * ((X / b)**2.0 + (Y / b)**2.0)) + 10
# Create a MAGsurvey
rxLoc = np.c_[mkvc(X.T), mkvc(Y.T), mkvc(Z.T)]
rxList = magnetics.receivers.Point(rxLoc)
srcField = magnetics.sources.SourceField(receiver_list=[rxList],
parameters=H0)
survey = magnetics.survey.Survey(srcField)
###############################################################################
# Inversion Mesh
# Create a mesh
h = [5, 5, 5]
padDist = np.ones((3, 2)) * 100
mesh = mesh_builder_xyz(rxLoc,
h,
padding_distance=padDist,
depth_core=100,
mesh_type="tree")
mesh = refine_tree_xyz(mesh,
topo,
method="surface",
octree_levels=[4, 4],
finalize=True)
# Define an active cells from topo
actv = utils.surface2ind_topo(mesh, topo)
nC = int(actv.sum())
# Convert the inclination declination to vector in Cartesian
M_xyz = utils.mat_utils.dip_azimuth2cartesian(
np.ones(nC) * M[0],
np.ones(nC) * M[1])
# Get the indicies of the magnetized block
ind = utils.model_builder.getIndicesBlock(
np.r_[-20, -20, -10],
np.r_[20, 20, 25],
mesh.gridCC,
)[0]
# Assign magnetization value, inducing field strength will
# be applied in by the :class:`SimPEG.PF.Magnetics` problem
model = np.zeros(mesh.nC)
model[ind] = chi_e
# Remove air cells
model = model[actv]
# Creat reduced identity map
idenMap = maps.IdentityMap(nP=nC)
# Create the forward model operator
simulation = magnetics.Simulation3DIntegral(
survey=survey,
mesh=mesh,
chiMap=idenMap,
actInd=actv,
store_sensitivities="forward_only",
)
simulation.M = M_xyz
# Compute some data and add some random noise
synthetic_data = simulation.dpred(model)
# Split the data in components
nD = rxLoc.shape[0]
std = 5 # nT
synthetic_data += np.random.randn(nD) * std
wd = np.ones(nD) * std
# Assigne data and uncertainties to the survey
data_object = data.Data(survey, dobs=synthetic_data, noise_floor=wd)
######################################################################
# Equivalent Source
# Get the active cells for equivalent source is the top only
surf = utils.model_utils.surface_layer_index(mesh, topo)
nC = np.count_nonzero(surf) # Number of active cells
mstart = np.ones(nC) * 1e-4
# Create active map to go from reduce set to full
surfMap = maps.InjectActiveCells(mesh, surf, np.nan)
# Create identity map
idenMap = maps.IdentityMap(nP=nC)
# Create static map
simulation = magnetics.simulation.Simulation3DIntegral(
mesh=mesh,
survey=survey,
chiMap=idenMap,
actInd=surf,
store_sensitivities="ram",
)
simulation.model = mstart
# Create a regularization function, in this case l2l2
reg = regularization.Sparse(mesh,
indActive=surf,
mapping=maps.IdentityMap(nP=nC),
alpha_z=0)
reg.mref = np.zeros(nC)
# Specify how the optimization will proceed, set susceptibility bounds to inf
opt = optimization.ProjectedGNCG(
maxIter=10,
lower=-np.inf,
upper=np.inf,
maxIterLS=5,
maxIterCG=5,
tolCG=1e-3,
)
# Define misfit function (obs-calc)
dmis = data_misfit.L2DataMisfit(simulation=simulation,
data=data_object)
# Create the default L2 inverse problem from the above objects
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# Specify how the initial beta is found
betaest = directives.BetaEstimate_ByEig(beta0_ratio=2)
# Target misfit to stop the inversion,
# try to fit as much as possible of the signal, we don't want to lose anything
IRLS = directives.Update_IRLS(f_min_change=1e-3,
minGNiter=1,
beta_tol=1e-1,
max_irls_iterations=5)
update_Jacobi = directives.UpdatePreconditioner()
# Put all the parts together
inv = inversion.BaseInversion(
invProb, directiveList=[betaest, IRLS, update_Jacobi])
# Run the equivalent source inversion
print("Solving for Equivalent Source")
mrec = inv.run(mstart)
########################################################
# Forward Amplitude Data
# ----------------------
#
# Now that we have an equialent source layer, we can forward model alh three
# components of the field and add them up: :math:`|B| = \sqrt{( Bx^2 + Bx^2 + Bx^2 )}`
#
rxList = magnetics.receivers.Point(rxLoc,
components=["bx", "by", "bz"])
srcField = magnetics.sources.SourceField(receiver_list=[rxList],
parameters=H0)
surveyAmp = magnetics.survey.Survey(srcField)
simulation = magnetics.simulation.Simulation3DIntegral(
mesh=mesh,
survey=surveyAmp,
chiMap=idenMap,
actInd=surf,
is_amplitude_data=True,
store_sensitivities="forward_only",
)
bAmp = simulation.fields(mrec)
######################################################################
# Amplitude Inversion
# -------------------
#
# Now that we have amplitude data, we can invert for an effective
# susceptibility. This is a non-linear inversion.
#
# Create active map to go from reduce space to full
actvMap = maps.InjectActiveCells(mesh, actv, -100)
nC = int(actv.sum())
# Create identity map
idenMap = maps.IdentityMap(nP=nC)
mstart = np.ones(nC) * 1e-4
# Create the forward model operator
simulation = magnetics.simulation.Simulation3DIntegral(
survey=surveyAmp,
mesh=mesh,
chiMap=idenMap,
actInd=actv,
is_amplitude_data=True,
)
data_obj = data.Data(survey, dobs=bAmp, noise_floor=wd)
# Create a sparse regularization
reg = regularization.Sparse(mesh, indActive=actv, mapping=idenMap)
reg.norms = np.c_[1, 0, 0, 0]
reg.mref = np.zeros(nC)
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=simulation, data=data_obj)
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=10,
lower=0.0,
upper=1.0,
maxIterLS=5,
maxIterCG=5,
tolCG=1e-3)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
# Here is the list of directives
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1)
# Specify the sparse norms
IRLS = directives.Update_IRLS(
max_irls_iterations=5,
f_min_change=1e-3,
minGNiter=1,
coolingRate=1,
beta_search=False,
)
# Special directive specific to the mag amplitude problem. The sensitivity
# weights are update between each iteration.
update_SensWeight = directives.UpdateSensitivityWeights()
update_Jacobi = directives.UpdatePreconditioner()
# Put all together
self.inv = inversion.BaseInversion(
invProb,
directiveList=[update_SensWeight, betaest, IRLS, update_Jacobi])
self.mstart = mstart
self.model = model
self.sim = simulation
def setUp(self):
ndv = -100
# Create a self.mesh
dx = 5.0
hxind = [(dx, 5, -1.3), (dx, 5), (dx, 5, 1.3)]
hyind = [(dx, 5, -1.3), (dx, 5), (dx, 5, 1.3)]
hzind = [(dx, 5, -1.3), (dx, 6)]
self.mesh = discretize.TensorMesh([hxind, hyind, hzind], "CCC")
# Get index of the center
midx = int(self.mesh.nCx / 2)
midy = int(self.mesh.nCy / 2)
# Lets create a simple Gaussian topo and set the active cells
[xx, yy] = np.meshgrid(self.mesh.vectorNx, self.mesh.vectorNy)
zz = -np.exp((xx**2 + yy**2) / 75**2) + self.mesh.vectorNz[-1]
# Go from topo to actv cells
topo = np.c_[utils.mkvc(xx), utils.mkvc(yy), utils.mkvc(zz)]
actv = utils.surface2ind_topo(self.mesh, topo, "N")
actv = np.where(actv)[0]
# Create active map to go from reduce space to full
self.actvMap = maps.InjectActiveCells(self.mesh, actv, -100)
nC = len(actv)
# Create and array of observation points
xr = np.linspace(-20.0, 20.0, 20)
yr = np.linspace(-20.0, 20.0, 20)
X, Y = np.meshgrid(xr, yr)
# Move the observation points 5m above the topo
Z = -np.exp((X**2 + Y**2) / 75**2) + self.mesh.vectorNz[-1] + 5.0
# Create a MAGsurvey
locXYZ = np.c_[utils.mkvc(X.T), utils.mkvc(Y.T), utils.mkvc(Z.T)]
rxLoc = gravity.Point(locXYZ)
srcField = gravity.SourceField([rxLoc])
survey = gravity.Survey(srcField)
# We can now create a density model and generate data
# Here a simple block in half-space
model = np.zeros((self.mesh.nCx, self.mesh.nCy, self.mesh.nCz))
model[(midx - 2):(midx + 2), (midy - 2):(midy + 2), -6:-2] = 0.5
model = utils.mkvc(model)
self.model = model[actv]
# Create active map to go from reduce set to full
actvMap = maps.InjectActiveCells(self.mesh, actv, ndv)
# Create reduced identity map
idenMap = maps.IdentityMap(nP=nC)
# Create the forward model operator
sim = gravity.Simulation3DIntegral(
self.mesh,
survey=survey,
rhoMap=idenMap,
actInd=actv,
store_sensitivities="ram",
)
# Compute linear forward operator and compute some data
# computing sensitivities to ram is best using dask processes
with dask.config.set(scheduler="processes"):
data = sim.make_synthetic_data(self.model,
relative_error=0.0,
noise_floor=0.001,
add_noise=True)
print(sim.G)
# Create a regularization
reg = regularization.Sparse(self.mesh, indActive=actv, mapping=idenMap)
reg.norms = np.c_[0, 0, 0, 0]
reg.gradientType = "component"
# reg.eps_p, reg.eps_q = 5e-2, 1e-2
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=sim, data=data)
# Add directives to the inversion
opt = optimization.ProjectedGNCG(maxIter=100,
lower=-1.0,
upper=1.0,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt, beta=1e8)
# Here is where the norms are applied
IRLS = directives.Update_IRLS(f_min_change=1e-4, minGNiter=1)
update_Jacobi = directives.UpdatePreconditioner()
sensitivity_weights = directives.UpdateSensitivityWeights(
everyIter=False)
self.inv = inversion.BaseInversion(
invProb, directiveList=[IRLS, sensitivity_weights, update_Jacobi])
self.sim = sim
def setUp(self):
np.random.seed(0)
# First we need to define the direction of the inducing field
# As a simple case, we pick a vertical inducing field of magnitude
# 50,000nT.
# From old convention, field orientation is given as an
# azimuth from North (positive clockwise)
# and dip from the horizontal (positive downward).
H0 = (50000.0, 90.0, 0.0)
# Create a mesh
h = [5, 5, 5]
padDist = np.ones((3, 2)) * 100
nCpad = [2, 4, 2]
# Create grid of points for topography
# Lets create a simple Gaussian topo and set the active cells
[xx, yy] = np.meshgrid(np.linspace(-200.0, 200.0, 50),
np.linspace(-200.0, 200.0, 50))
b = 100
A = 50
zz = A * np.exp(-0.5 * ((xx / b)**2.0 + (yy / b)**2.0))
# We would usually load a topofile
topo = np.c_[utils.mkvc(xx), utils.mkvc(yy), utils.mkvc(zz)]
# Create and array of observation points
xr = np.linspace(-100.0, 100.0, 20)
yr = np.linspace(-100.0, 100.0, 20)
X, Y = np.meshgrid(xr, yr)
Z = A * np.exp(-0.5 * ((X / b)**2.0 + (Y / b)**2.0)) + 5
# Create a MAGsurvey
xyzLoc = np.c_[utils.mkvc(X.T), utils.mkvc(Y.T), utils.mkvc(Z.T)]
rxLoc = mag.Point(xyzLoc)
srcField = mag.SourceField([rxLoc], parameters=H0)
survey = mag.Survey(srcField)
# self.mesh.finalize()
self.mesh = meshutils.mesh_builder_xyz(
xyzLoc,
h,
padding_distance=padDist,
mesh_type="TREE",
)
self.mesh = meshutils.refine_tree_xyz(
self.mesh,
topo,
method="surface",
octree_levels=nCpad,
octree_levels_padding=nCpad,
finalize=True,
)
# Define an active cells from topo
actv = utils.surface2ind_topo(self.mesh, topo)
nC = int(actv.sum())
# We can now create a susceptibility model and generate data
# Lets start with a simple block in half-space
self.model = utils.model_builder.addBlock(
self.mesh.gridCC,
np.zeros(self.mesh.nC),
np.r_[-20, -20, -15],
np.r_[20, 20, 20],
0.05,
)[actv]
# Create active map to go from reduce set to full
self.actvMap = maps.InjectActiveCells(self.mesh, actv, np.nan)
# Creat reduced identity map
idenMap = maps.IdentityMap(nP=nC)
# Create the forward model operator
sim = mag.Simulation3DIntegral(
self.mesh,
survey=survey,
chiMap=idenMap,
actInd=actv,
store_sensitivities="ram",
)
self.sim = sim
data = sim.make_synthetic_data(self.model,
relative_error=0.0,
noise_floor=1.0,
add_noise=True)
# Create a regularization
reg = regularization.Sparse(self.mesh, indActive=actv, mapping=idenMap)
reg.norms = np.c_[0, 0, 0, 0]
reg.mref = np.zeros(nC)
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=sim, data=data)
# Add directives to the inversion
opt = optimization.ProjectedGNCG(
maxIter=10,
lower=0.0,
upper=10.0,
maxIterLS=5,
maxIterCG=5,
tolCG=1e-4,
stepOffBoundsFact=1e-4,
)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt, beta=1e6)
# Here is where the norms are applied
# Use pick a treshold parameter empirically based on the distribution of
# model parameters
IRLS = directives.Update_IRLS(f_min_change=1e-3,
max_irls_iterations=20,
beta_tol=1e-1,
beta_search=False)
update_Jacobi = directives.UpdatePreconditioner()
sensitivity_weights = directives.UpdateSensitivityWeights()
self.inv = inversion.BaseInversion(
invProb, directiveList=[IRLS, sensitivity_weights, update_Jacobi])
data_vrm = data.Data(dobs=dobs,
survey=survey_vrm,
relative_error=rel_err,
noise_floor=eps)
# Setup and run inversion
dmis = data_misfit.L2DataMisfit(simulation=problem_inv, data=data_vrm)
w = utils.mkvc((np.sum(np.array(problem_inv.A)**2, axis=0)))**0.5
w = w / np.max(w)
w = w
reg = regularization.SimpleSmall(mesh=mesh, indActive=actCells, cell_weights=w)
opt = optimization.ProjectedGNCG(maxIter=20,
lower=0.0,
upper=1e-2,
maxIterLS=20,
tolCG=1e-4)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
directives = [
directives.BetaSchedule(coolingFactor=2, coolingRate=1),
directives.TargetMisfit(),
]
inv = inversion.BaseInversion(invProb, directiveList=directives)
xi_0 = 1e-3 * np.ones(actCells.sum())
xi_rec = inv.run(xi_0)
# Predict VRM response at all times for recovered model
survey_vrm.set_active_interval(0.0, 1.0)
fields_pre = problem_inv.dpred(xi_rec)
# normalized by the data's standard deviation.
dmis = data_misfit.L2DataMisfit(simulation=simulation, data=data_object)
# Define the regularization (model objective function). Here, 'p' defines the
# the norm of the smallness term and 'q' defines the norm of the smoothness
# term.
reg = regularization.Sparse(mesh, mapping=model_map)
reg.mref = starting_model
p = 0
q = 0
reg.norms = np.c_[p, q]
# Define how the optimization problem is solved. Here we will use an inexact
# Gauss-Newton approach that employs the conjugate gradient solver.
opt = optimization.ProjectedGNCG(maxIter=100,
maxIterLS=20,
maxIterCG=20,
tolCG=1e-3)
# Define the inverse problem
inv_prob = inverse_problem.BaseInvProblem(dmis, reg, opt)
#######################################################################
# Define Inversion Directives
# ---------------------------
#
# Here we define any directives that are carried out during the inversion. This
# includes the cooling schedule for the trade-off parameter (beta), stopping
# criteria for the inversion and saving inversion results at each iteration.
#
# Apply and update sensitivity weighting as the model updates
# Define the data misfit. Here the data misfit is the L2 norm of the weighted
# residual between the observed data and the data predicted for a given model.
# Within the data misfit, the residual between predicted and observed data are
# normalized by the data's standard deviation.
dmis = data_misfit.L2DataMisfit(data=data_object, simulation=simulation)
dmis.W = utils.sdiag(1 / uncertainties)
# Define the regularization (model objective function).
reg = regularization.Sparse(mesh, indActive=ind_active, mapping=model_map)
reg.norms = np.c_[0, 2, 2, 2]
# Define how the optimization problem is solved. Here we will use a projected
# Gauss-Newton approach that employs the conjugate gradient solver.
opt = optimization.ProjectedGNCG(maxIter=100,
lower=-1.0,
upper=1.0,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3)
# Here we define the inverse problem that is to be solved
inv_prob = inverse_problem.BaseInvProblem(dmis, reg, opt)
#######################################################################
# Define Inversion Directives
# ---------------------------
#
# Here we define any directiveas that are carried out during the inversion. This
# includes the cooling schedule for the trade-off parameter (beta), stopping
# criteria for the inversion and saving inversion results at each iteration.
#
def run(plotIt=True):
nC = 40
de = 1.0
h = np.ones(nC) * de / nC
M = discretize.TensorMesh([h, h])
y = np.linspace(M.vectorCCy[0], M.vectorCCx[-1], int(np.floor(nC / 4)))
rlocs = np.c_[0 * y + M.vectorCCx[-1], y]
rx = tomo.Rx(rlocs)
source_list = [
tomo.Src(location=np.r_[M.vectorCCx[0], yi], receiver_list=[rx])
for yi in y
]
# phi model
phi0 = 0
phi1 = 0.65
phitrue = utils.model_builder.defineBlock(M.gridCC, [0.4, 0.6], [0.6, 0.4],
[phi1, phi0])
knownVolume = np.sum(phitrue * M.vol)
print("True Volume: {}".format(knownVolume))
# Set up true conductivity model and plot the model transform
sigma0 = np.exp(1)
sigma1 = 1e4
if plotIt:
fig, ax = plt.subplots(1, 1)
sigmaMapTest = maps.SelfConsistentEffectiveMedium(nP=1000,
sigma0=sigma0,
sigma1=sigma1,
rel_tol=1e-1,
maxIter=150)
testphis = np.linspace(0.0, 1.0, 1000)
sigetest = sigmaMapTest * testphis
ax.semilogy(testphis, sigetest)
ax.set_title("Model Transform")
ax.set_xlabel("$\\varphi$")
ax.set_ylabel("$\sigma$")
sigmaMap = maps.SelfConsistentEffectiveMedium(M,
sigma0=sigma0,
sigma1=sigma1)
# scale the slowness so it is on a ~linear scale
slownessMap = maps.LogMap(M) * sigmaMap
# set up the true sig model and log model dobs
sigtrue = sigmaMap * phitrue
# modt = Model.BaseModel(M);
slownesstrue = slownessMap * phitrue # true model (m = log(sigma))
# set up the problem and survey
survey = tomo.Survey(source_list)
problem = tomo.Simulation(M, survey=survey, slownessMap=slownessMap)
if plotIt:
fig, ax = plt.subplots(1, 1)
cb = plt.colorbar(M.plotImage(phitrue, ax=ax)[0], ax=ax)
survey.plot(ax=ax)
cb.set_label("$\\varphi$")
# get observed data
data = problem.make_synthetic_data(phitrue,
relative_error=0.03,
add_noise=True)
dpred = problem.dpred(np.zeros(M.nC))
# objective function pieces
reg = regularization.Tikhonov(M)
dmis = data_misfit.L2DataMisfit(simulation=problem, data=data)
dmisVol = Volume(mesh=M, knownVolume=knownVolume)
beta = 0.25
maxIter = 15
# without the volume regularization
opt = optimization.ProjectedGNCG(maxIter=maxIter, lower=0.0, upper=1.0)
opt.remember("xc")
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt, beta=beta)
inv = inversion.BaseInversion(invProb)
mopt1 = inv.run(np.zeros(M.nC) + 1e-16)
print("\nTotal recovered volume (no vol misfit term in inversion): "
"{}".format(dmisVol(mopt1)))
# with the volume regularization
vol_multiplier = 9e4
reg2 = reg
dmis2 = dmis + vol_multiplier * dmisVol
opt2 = optimization.ProjectedGNCG(maxIter=maxIter, lower=0.0, upper=1.0)
opt2.remember("xc")
invProb2 = inverse_problem.BaseInvProblem(dmis2, reg2, opt2, beta=beta)
inv2 = inversion.BaseInversion(invProb2)
mopt2 = inv2.run(np.zeros(M.nC) + 1e-16)
print("\nTotal volume (vol misfit term in inversion): {}".format(
dmisVol(mopt2)))
# plot results
if plotIt:
fig, ax = plt.subplots(1, 1)
ax.plot(data.dobs)
ax.plot(dpred)
ax.plot(problem.dpred(mopt1), "o")
ax.plot(problem.dpred(mopt2), "s")
ax.legend(["dobs", "dpred0", "dpred w/o Vol", "dpred with Vol"])
fig, ax = plt.subplots(1, 3, figsize=(16, 4))
im0 = M.plotImage(phitrue, ax=ax[0])[0]
im1 = M.plotImage(mopt1, ax=ax[1])[0]
im2 = M.plotImage(mopt2, ax=ax[2])[0]
for im in [im0, im1, im2]:
im.set_clim([0.0, phi1])
plt.colorbar(im0, ax=ax[0])
plt.colorbar(im1, ax=ax[1])
plt.colorbar(im2, ax=ax[2])
ax[0].set_title("true, vol: {:1.3e}".format(knownVolume))
ax[1].set_title("recovered(no Volume term), vol: {:1.3e} ".format(
dmisVol(mopt1)))
ax[2].set_title("recovered(with Volume term), vol: {:1.3e} ".format(
dmisVol(mopt2)))
plt.tight_layout()
# pre-conditioner
update_Jacobi = directives.UpdatePreconditioner()
# iteratively balance the scaling of the data misfits
scaling_init = directives.ScalingMultipleDataMisfits_ByEig(
chi0_ratio=[1.0, 100.0])
scale_schedule = directives.JointScalingSchedule(verbose=True)
# Create inverse problem
# Optimization
# set lower and upper bounds
lowerbound = np.r_[-2.0 * np.ones(actvMap.nP), 0.0 * np.ones(actvMap.nP)]
upperbound = np.r_[0.0 * np.ones(actvMap.nP), 1e-1 * np.ones(actvMap.nP)]
opt = optimization.ProjectedGNCG(
maxIter=30,
lower=lowerbound,
upper=upperbound,
maxIterLS=20,
maxIterCG=100,
tolCG=1e-4,
)
# create inverse problem
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
inv = inversion.BaseInversion(
invProb,
# directives: evaluate alphas (and data misfits scales) before beta
directiveList=[
Alphas,
scaling_init,
beta,
update_smallness,
targets,
scale_schedule,
def run(plotIt=True):
H0 = (50000.0, 90.0, 0.0)
# Create a mesh
dx = 5.0
hxind = [(dx, 5, -1.3), (dx, 10), (dx, 5, 1.3)]
hyind = [(dx, 5, -1.3), (dx, 10), (dx, 5, 1.3)]
hzind = [(dx, 5, -1.3), (dx, 10)]
mesh = discretize.TensorMesh([hxind, hyind, hzind], "CCC")
# Lets create a simple Gaussian topo and set the active cells
[xx, yy] = np.meshgrid(mesh.vectorNx, mesh.vectorNy)
zz = -np.exp((xx ** 2 + yy ** 2) / 75 ** 2) + mesh.vectorNz[-1]
# We would usually load a topofile
topo = np.c_[utils.mkvc(xx), utils.mkvc(yy), utils.mkvc(zz)]
# Go from topo to array of indices of active cells
actv = utils.surface2ind_topo(mesh, topo, "N")
actv = np.where(actv)[0]
# Create and array of observation points
xr = np.linspace(-20.0, 20.0, 20)
yr = np.linspace(-20.0, 20.0, 20)
X, Y = np.meshgrid(xr, yr)
# Move the observation points 5m above the topo
Z = -np.exp((X ** 2 + Y ** 2) / 75 ** 2) + mesh.vectorNz[-1] + 5.0
# Create a MAGsurvey
rxLoc = np.c_[utils.mkvc(X.T), utils.mkvc(Y.T), utils.mkvc(Z.T)]
rxLoc = magnetics.Point(rxLoc)
srcField = magnetics.SourceField([rxLoc], parameters=H0)
survey = magnetics.Survey(srcField)
# We can now create a susceptibility model and generate data
model = np.zeros(mesh.nC)
# Change values in half the domain
model[mesh.gridCC[:, 0] < 0] = 0.01
# Add a block in half-space
model = utils.model_builder.addBlock(
mesh.gridCC, model, np.r_[-10, -10, 20], np.r_[10, 10, 40], 0.05
)
model = utils.mkvc(model)
model = model[actv]
# Create active map to go from reduce set to full
actvMap = maps.InjectActiveCells(mesh, actv, np.nan)
# Create reduced identity map
idenMap = maps.IdentityMap(nP=len(actv))
# Create the forward model operator
prob = magnetics.Simulation3DIntegral(
mesh,
survey=survey,
chiMap=idenMap,
actInd=actv,
store_sensitivities="forward_only",
)
# Compute linear forward operator and compute some data
data = prob.make_synthetic_data(
model, relative_error=0.0, noise_floor=1, add_noise=True
)
# Create a homogenous maps for the two domains
domains = [mesh.gridCC[actv, 0] < 0, mesh.gridCC[actv, 0] >= 0]
homogMap = maps.SurjectUnits(domains)
# Create a wire map for a second model space, voxel based
wires = maps.Wires(("h**o", len(domains)), ("hetero", len(actv)))
# Create Sum map
sumMap = maps.SumMap([homogMap * wires.h**o, wires.hetero])
# Create the forward model operator
prob = magnetics.Simulation3DIntegral(
mesh, survey=survey, chiMap=sumMap, actInd=actv, store_sensitivities="ram"
)
# Make depth weighting
wr = np.zeros(sumMap.shape[1])
print(prob.nC)
# print(prob.M.shape) # why does this reset nC
G = prob.G
# Take the cell number out of the scaling.
# Want to keep high sens for large volumes
scale = utils.sdiag(
np.r_[utils.mkvc(1.0 / homogMap.P.sum(axis=0)), np.ones_like(actv)]
)
for ii in range(survey.nD):
wr += (
(prob.G[ii, :] * prob.chiMap.deriv(np.ones(sumMap.shape[1]) * 1e-4) * scale)
/ data.standard_deviation[ii]
) ** 2.0
# Scale the model spaces independently
wr[wires.h**o.index] /= np.max((wires.h**o * wr))
wr[wires.hetero.index] /= np.max(wires.hetero * wr)
wr = wr ** 0.5
## Create a regularization
# For the homogeneous model
regMesh = discretize.TensorMesh([len(domains)])
reg_m1 = regularization.Sparse(regMesh, mapping=wires.h**o)
reg_m1.cell_weights = wires.h**o * wr
reg_m1.norms = np.c_[0, 2, 2, 2]
reg_m1.mref = np.zeros(sumMap.shape[1])
# Regularization for the voxel model
reg_m2 = regularization.Sparse(mesh, indActive=actv, mapping=wires.hetero)
reg_m2.cell_weights = wires.hetero * wr
reg_m2.norms = np.c_[0, 1, 1, 1]
reg_m2.mref = np.zeros(sumMap.shape[1])
reg = reg_m1 + reg_m2
# Data misfit function
dmis = data_misfit.L2DataMisfit(simulation=prob, data=data)
# Add directives to the inversion
opt = optimization.ProjectedGNCG(
maxIter=100,
lower=0.0,
upper=1.0,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3,
tolG=1e-3,
eps=1e-6,
)
invProb = inverse_problem.BaseInvProblem(dmis, reg, opt)
betaest = directives.BetaEstimate_ByEig()
# Here is where the norms are applied
# Use pick a threshold parameter empirically based on the distribution of
# model parameters
IRLS = directives.Update_IRLS(f_min_change=1e-3, minGNiter=1)
update_Jacobi = directives.UpdatePreconditioner()
inv = inversion.BaseInversion(invProb, directiveList=[IRLS, betaest, update_Jacobi])
# Run the inversion
m0 = np.ones(sumMap.shape[1]) * 1e-4 # Starting model
prob.model = m0
mrecSum = inv.run(m0)
if plotIt:
mesh.plot_3d_slicer(
actvMap * model,
aspect="equal",
zslice=30,
pcolorOpts={"cmap": "inferno_r"},
transparent="slider",
)
mesh.plot_3d_slicer(
actvMap * sumMap * mrecSum,
aspect="equal",
zslice=30,
pcolorOpts={"cmap": "inferno_r"},
transparent="slider",
)