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Question about structural constrain inversion technique structural weighting adjustment #658
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This is indeed a very good question of both practical and methodological relevance. As for any other data, structural information also bears uncertainty that should be accounted for. A few ideas:
or any combination of it. I'd be interested in other peoples experience, knowing about existing papers. Maybe we should make a discussion about this issue? |
One can set such an interface weight of a forward operator by
(The marker should maybe have a marker different from 1 to be distinguished from the outer boundary.) In case of a manager, the forward operator is
Please try it and report back, because I've never used it. |
Thank you very much for the useful advice! I found that the forward operator of ERT Manager has no setting for the # Set such an interface weight of a FORWARD OPERATOR
fop = ert.ERTModelling()
fop.setMesh(mesh3)
fop.regionManager().setInterfaceConstraint(2, 0.5)
fop.setData(data)
inv3 = pg.Inversion(fop=fop, verbose=True)
transLog = pg.trans.TransLog()
inv3.modelTrans = transLog
inv3.dataTrans = transLog
# Run the inversion with the preset data. The Inversion mesh will be created
# with default settings.
constrained_model = inv3.run(data['rhoa'], data['err'],lam=100) |
And after the SEG webinar I saw the demonstration of the same inversion setting of the forward operator directly using # The same inversion setting can be done with the ERTManager
mgr3 = ert.ERTManager(data)
mgr3.setMesh(mesh3)
mgr3.fop.regionManager().setInterfaceConstraint(2, 0.5)
mgr3.invert(lam=100, verbose=True) |
Exactly! So in this case it is not necessary to create the fop by yourself. In the next version, we will provide
just like
|
Thanks! I'm appreciate and look forward to it! |
Would be interesting to see a systematic study how the strength influences the results. I just saw that your synthetic modelling includes severe modelling errors showing unrealistically low apparent resistivities for larger dipole separations. Reason are wrong boundary conditions. You should append a triangle boundary with "world boundary conditions" around your model to avoid this. There are several examples, just search for |
Great! Thank you for sharing this comparison. |
Question about structural constrain inversion technique structural weighting adjustment
Problem description
I conducted a synthetic test of a slope model with a curved slip surface case with the structural constrain technique. Based on the example of the website about the structural constrains. I created a model with two layers: the regolith layer and the bedrock of the slope. Between these two layers is a curved slip interface.
According to (2011, Rucker) and (2020, Jiang), the settings for sharp boundary weighting suggest that the program should directly set the smoothness weighting of that boundary to 0, creating a very apparent resistivity contrast.
However, I'm curious if there's a way to manually adjust the structural weighting of the inversion smoothness constraint matrix$\bold{C}$ to a specific quantity, which could lead to a resistivity model with less "sharp" structural contrast. When we are not entirely confident in our structural interface from seismic or GPR.
Your environment
Steps to reproduce (my code)
The results
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