stanford-imaging team mailing list archive

[Michael Cardiff <michaelcardiff@xxxxxxxxxxxxxx>]

Hi Hatef -

I have a 3D code, based on the FFT-based methods, that can generate
unconditional realizations with 1million + grid-cells. We can discuss
this if you're interested in using it. Of course, if Arvind has code
for doing unconditional realizations using his techniques, I'd be
curious about those as well!

For the data, I believe in the early inversions I was trying I was
using about half the data. Based on discussions with Baptiste, some of
the datasets are more noisy than others, so I just picked some of the
slices that he had indicated were more reliable.

Another strategy, of course, would be to just randomly select a subset
of the data. 200,000 measurements is a bit much for doing
geostatistical approaches, since the inverted matrices (HQHt+R HX; HX
0) are non-sparse and even a (# measurements x # measurements) matrix
will be quite cumbersome to store. Around 100,000 could be manageable
on a machine with a lot of RAM.

The size of this dataset is actually what got me thinking about
sequential data inclusion methods... perhaps using the techniques you
are planning, you could successively incorporate more and more
measurements?

Feel free to let me know what you're thinking and we can brainstorm further...

-Mike

On Sat, Feb 19, 2011 at 6:12 PM, Hatef Monajemi <monajemi@xxxxxxxxxxxx> wrote:
> Hello ,
>
> I wonder if Arvind has already developed the code for generating
> unconditional realizations in 3D at least for structured grid. 3D
> calculation seems to be more in need of methods that save storage.
>
> Also, Mike, can you give us an estimate of the size of problem you are
> considering for 3D inversion of GPR data in BHRS. There is around 200,000
> measurements of travel time and I wonder if you are using all or a subset of
> that.
>
> Please reply all so that people can keep track of what research is going on
> in the team.
>
> Thanks,
> Hatef
>
> --------------
> Hatef Monajemi
> PhD Student
> Environmental Fluid Mechanics and Hydrology
> Department of Civil and Environmental Engineering
> Stanford University
> 473 Via Ortega, Y2E2 Bldg, Room M25
> Stanford, CA 94305
> Email: monajemi@xxxxxxxxxxxx
> Web: http://www.stanford.edu/~monajemi/
>
>
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-- 
Michael Cardiff, Ph.D.
Assistant Research Professor
Center for Geophysical Investigation of the Shallow Subsurface (CGISS)
Department of Geosciences
1910 University Drive, MS-1536
Boise State University
Boise, ID 83725-1536
phone: 208-426-4678
fax:     208-426-3888
email: michaelcardiff@xxxxxxxxxxxxxx
http://earth.boisestate.edu/michaelcardiff