# Get unique geo units
geoUnits = np.unique(mgeo).tolist()
# Compute an a median value for each homogeneous units
mUnit = np.asarray([np.median(mgeo[mgeo == unit]) for unit in geoUnits])
# Build list of indecies for the geounits
index = []
nCunit = []
for unit in geoUnits:
index += [mgeo == unit]
nCunit += [int((mgeo == unit).sum())]
nC = len(index)
# Creat reduced identity map
homogMap = Maps.SurjectUnits(index)
# Create a wire map to link the homogeneous and heterogeneous spaces
wires = Maps.Wires(('h**o', nC), ('hetero', int(actv.sum())))
# Create Sum map for the global inverse
sumMap = Maps.SumMap([homogMap*wires.h**o, wires.hetero])
# LOOP THROUGH TILES
surveyMask = np.ones(survey.nD, dtype='bool') # Keep track of locs used
wrGlobal = np.zeros(int(nC + actv.sum())) # Global sensitivity weights
if tileProblem:
# Loop over different tile size and break
# problem to fit in memory
usedRAM = np.inf
def run(plotIt=True):
H0 = (50000., 90., 0.)
# Create a mesh
dx = 5.
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 = Mesh.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 actv cells
actv = Utils.surface2ind_topo(mesh, topo, 'N')
actv = np.asarray([inds for inds, elem in enumerate(actv, 1) if elem],
dtype=int) - 1
# Create active map to go from reduce space to full
actvMap = Maps.InjectActiveCells(mesh, actv, -100)
nC = len(actv)
# Create and array of observation points
xr = np.linspace(-20., 20., 20)
yr = np.linspace(-20., 20., 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.
# Create a MAGsurvey
rxLoc = np.c_[Utils.mkvc(X.T), Utils.mkvc(Y.T), Utils.mkvc(Z.T)]
rxLoc = PF.BaseMag.RxObs(rxLoc)
srcField = PF.BaseMag.SrcField([rxLoc], param=H0)
survey = PF.BaseMag.LinearSurvey(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.ModelBuilder.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)
# Creat reduced identity map
idenMap = Maps.IdentityMap(nP=nC)
# Create the forward model operator
prob = PF.Magnetics.MagneticIntegral(mesh, chiMap=idenMap, actInd=actv)
# Pair the survey and problem
survey.pair(prob)
# Compute linear forward operator and compute some data
d = prob.fields(model)
# Add noise and uncertainties
# We add some random Gaussian noise (1nT)
data = d + np.random.randn(len(d))
wd = np.ones(len(data)) * 1. # Assign flat uncertainties
survey.dobs = data
survey.std = wd
survey.mtrue = model
# Plot the data
rxLoc = survey.srcField.rxList[0].locs
# Creat 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 = PF.Magnetics.MagneticIntegral(mesh, chiMap=sumMap, actInd=actv)
# Pair the survey and problem
survey.unpair()
survey.pair(prob)
# Make depth weighting
wr = np.zeros(sumMap.shape[1])
# Take the cell number out of the scaling.
# Want to keep high sens for large volumnes
scale = Utils.sdiag(np.r_[Utils.mkvc(1. / 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) /
survey.std[ii])**2.
# 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 = Mesh.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 = DataMisfit.l2_DataMisfit(survey)
dmis.W = 1 / wd
# Add directives to the inversion
opt = Optimization.ProjectedGNCG(maxIter=100,
lower=0.,
upper=1.,
maxIterLS=20,
maxIterCG=10,
tolCG=1e-3,
tolG=1e-3,
eps=1e-6)
invProb = InvProblem.BaseInvProblem(dmis, reg, opt)
betaest = Directives.BetaEstimate_ByEig()
# 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, 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')
