Gridding with breaklines?

Dear GMT developers,

Some time back (2010) there was a discussion on gridding with
breaklines (such as faults) and Joaquim Luis mentioned (see two
e-mails from him below) that he had his own code (gmtmbgrid.c) that
could implement this, and that GMT5 would implement this feature
inside surface command. However, when reading the documentation of
GMT5's surface, I could not find anything in this sense.

So my question is, will this feature be available in GMT5.? Or is it
beyond the present development of GMT?

Best wishes

Juan Diaz-Naveas


*Subject:*Re: contouring with faults
*From:*J Luis <[log in to unmask]
<https://listserv.hawaii.edu/cgi-bin/wa?LOGON=A2%3Dind1002%26L%3DGMT-HELP%26D%3D0%26T%3D0%26P%3D21782>>
*Reply-To:*World-Wide GMT Usage and Help Mailing List <[log in to
unmask] <https://listserv.hawaii.edu/cgi-bin/wa?LOGON=A2%3Dind1002%26L%3DGMT-HELP%26D%3D0%26T%3D0%26P%3D21782>>
*Date:*Wed, 3 Feb 2010 19:01:56 +0000
*Content-Type:*text/plainCarlos,

I'm afraid things can be a bit more complicated in what regards the
minimum curvature algorithm. It is not only a question of ignoring
what's in the other side of the fault because the solution is global (it
always fits a a surface over the entire domain). To have a real break
one would have to compute separate "side solutions", crop them along
each "not your zone side" and paste them together at the end.
As I said, I don't know how Surfer does it but it does it very well.

For ones who want to try the Soft breakline that I mentioned before, I
added it also to my gmtmbgrid mix. I have it temporarily at
http://w3.ualg.pt/~jluis/ftp/candi_data/gmtmbgrid.c

to compile, just save it in the the GMT src dir and add its name in the
makefile. The option of interest is -D<breakline_file.xyz>

Joaquim


*Subject:*Re: contouring with faults
*From:*J Luis <[log in to unmask]
<https://listserv.hawaii.edu/cgi-bin/wa?LOGON=A2%3Dind1002%26L%3DGMT-HELP%26D%3D0%26T%3D0%26P%3D20581>>
*Reply-To:*World-Wide GMT Usage and Help Mailing List <[log in to
unmask] <https://listserv.hawaii.edu/cgi-bin/wa?LOGON=A2%3Dind1002%26L%3DGMT-HELP%26D%3D0%26T%3D0%26P%3D20581>>
*Date:*Wed, 3 Feb 2010 18:28:26 +0000
*Content-Type:*text/plain

Mohan,

I'm not sure I understood what type of "with faults" you are referring
to. You also mention "surfer" but you say it "has become inactive". If
it is Golden Software Surfer, it has not become inactive and it has two
different types of operations of this kind:
- Breaklines and Faults
The first one, AKA soft breaklines, consists in inserting extra data on
each final grid node location coming from an external x,y,z data before
interpolation. As for the second one, I have no idea how it works. The
Surfer man just says that the interpolation algorithm does not cross the
fault lines.
The good news is that the soft breaklines is already implemented ... in
GMT5's surface, which is not yet ready for daylight.

BTW, which freeware program were you referring to as being capable to
"handle contours in presence of faults"?

Joaquim Luis

On 03-02-2010 02:45, V.C.Mohan wrote:
> I am trying to find if there is a way to contouring subsurface
> geological data  with faults. I tried to introduce by appending to
>  xyz data  some profiles of fault lines setting all z to NaN. Then I
> took a block mean. The output has no NaN fault trace at all but
> probably did not consider data across the NaN locations. Next running
> either surface or triangulate did not show up the fault. Then I tried
> once again appending the fault trace xyz (Nan) to the block mean data
> ensuring that the grid interval is same. Triangulate then produced
> some contouring with many blank regions, but not the way the faults
> come out in a normal contour map. surface as expected complained about
> duplicates and advised to run blockmean.
>
> Is there any other procedure I should try? Or should I give up faults
> altogether. There are commercial packages as well as atleast one
> freeware under sourceforge viz surfer that can handle contours in
> presence of faults. It appears that surfer has become inactive for
> several years. Will GMT consider implementing such an option?
> mohan
>

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