Geophysics functions [was Re: [GRASS-user] use pi number]

2008/8/23 José María Michia <jose.maria.michia@gmail.com>:

2008/8/23 Glynn Clements <glynn@gclements.plus.com>:

r.mapcalc doesn't have a definition for pi; you'll need to enter a
literal value.

Thanks Glynn. This sounds like a weak point for me.

I need to introduce "Pi" several times. Not for converting degrees to
radians. It is another class of applications. In this case to
calculate gravity anomalies.

José,

I have been interested in implementing potential fields function in
GRASS since long,
but I don't have the necessary background (I mean, I don't know the
equations) or the coding skills.
However, I can help you test/debug.

Maybe that could be the starting point for me to learn something about
it. Pointers to interesting sites/books/papers would be nice. =D
At my current job I have access to plenty of datasets and experts, so
we could use (borrow) further help =]

Glynn, ALL,
I would like to know where all these geophysics modules would fit.
I guess not in the i.* series, maybe in r.grav.* for gravity
data/functions or r.mag.* for magnetometry data.
--
Paulo Marcondes = PU1/PU2PIX
-22.915 -42.224 = GG86jc

2008/8/23 Paulo Marcondes <paulomarcondes@gmail.com>:

I have been interested in implementing potential fields function in
GRASS since long,
but I don't have the necessary background (I mean, I don't know the
equations) or the coding skills.

As for gravity equations, the Geological Survey of Canada has a
informative page: http://gsc.nrcan.gc.ca/gravity/formulae_e.php

However, we still don't have an answer to this:

I would like to know where all these geophysics modules would fit.
I guess not in the i.* series, maybe in r.grav.* for gravity
data/functions or r.mag.* for magnetometry data.

What do you think?
--
Paulo Marcondes = PU1/PU2PIX
-22.915 -42.224 = GG86jc

On Monday 25 August 2008 08:59:33 am Paulo Marcondes wrote:

2008/8/23 Paulo Marcondes <paulomarcondes@gmail.com>:
> I have been interested in implementing potential fields function in
> GRASS since long,
> but I don't have the necessary background (I mean, I don't know the
> equations) or the coding skills.

As for gravity equations, the Geological Survey of Canada has a
informative page: http://gsc.nrcan.gc.ca/gravity/formulae_e.php

However, we still don't have an answer to this:
> I would like to know where all these geophysics modules would fit.
> I guess not in the i.* series, maybe in r.grav.* for gravity
> data/functions or r.mag.* for magnetometry data.

Adding some more support behind geophysical routines / examples in GRASS, here
is a simple post illustrating some work with magnetic data in GRASS. See the
link to Stefan Maus' page for detailed descriptions and magnetic models.

http://casoilresource.lawr.ucdavis.edu/drupal/node/560

Cheers,

Dylan

--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341

2008/8/25 Dylan Beaudette <dylan.beaudette@gmail.com>:

On Monday 25 August 2008 08:59:33 am Paulo Marcondes wrote:

2008/8/23 Paulo Marcondes <paulomarcondes@gmail.com>:
> I have been interested in implementing potential fields function in
> GRASS since long,
> but I don't have the necessary background (I mean, I don't know the
> equations) or the coding skills.

As for gravity equations, the Geological Survey of Canada has a
informative page: http://gsc.nrcan.gc.ca/gravity/formulae_e.php

I've created a wiki page:

http://grass.osgeo.org/wiki/Gravity

At this moment, is only a first step. The info is not related directly
to GRASS, but I think that is correct to publish here. I look forward
to working alongside Paulo and others to add more information. Please,
correct me if I wrong

However, we still don't have an answer to this:
> I would like to know where all these geophysics modules would fit.
> I guess not in the i.* series, maybe in r.grav.* for gravity
> data/functions or r.mag.* for magnetometry data.

Adding some more support behind geophysical routines / examples in GRASS, here
is a simple post illustrating some work with magnetic data in GRASS. See the
link to Stefan Maus' page for detailed descriptions and magnetic models.

http://casoilresource.lawr.ucdavis.edu/drupal/node/560

I've created another wiki page and published this link:

http://grass.osgeo.org/wiki/Geomagnetism

Cheers,

Dylan

--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341
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On Tuesday 26 August 2008, José María Michia wrote:

2008/8/25 Dylan Beaudette <dylan.beaudette@gmail.com>:
> On Monday 25 August 2008 08:59:33 am Paulo Marcondes wrote:
>> 2008/8/23 Paulo Marcondes <paulomarcondes@gmail.com>:
>> > I have been interested in implementing potential fields function in
>> > GRASS since long,
>> > but I don't have the necessary background (I mean, I don't know the
>> > equations) or the coding skills.
>>
>> As for gravity equations, the Geological Survey of Canada has a
>> informative page: http://gsc.nrcan.gc.ca/gravity/formulae_e.php

I've created a wiki page:

http://grass.osgeo.org/wiki/Gravity

At this moment, is only a first step. The info is not related directly
to GRASS, but I think that is correct to publish here. I look forward
to working alongside Paulo and others to add more information. Please,
correct me if I wrong

Thanks. Another person/place to consult are Walter Smith / GMT mailing list.

Cheers,

Dylan

--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341

2008/8/26 José María Michia <jose.maria.michia@gmail.com>:

I've created a wiki page:

http://grass.osgeo.org/wiki/Gravity
http://grass.osgeo.org/wiki/Geomagnetism

I've edited them both. please check.

Dylan, quite informative pages, thanks. As for the GMT info, it is a
shame I am not much into GMT, maybe that is a grave fault on my part?

--
Paulo Marcondes = PU1/PU2PIX
-22.915 -42.224 = GG86jc

On Thursday 28 August 2008, Paulo Marcondes wrote:

2008/8/26 José María Michia <jose.maria.michia@gmail.com>:
> I've created a wiki page:
>
> http://grass.osgeo.org/wiki/Gravity
> http://grass.osgeo.org/wiki/Geomagnetism

I've edited them both. please check.

Dylan, quite informative pages, thanks. As for the GMT info, it is a
shame I am not much into GMT, maybe that is a grave fault on my part?

Thanks Paolo. I'll post any new material directly in the wiki. GMT is tough to
get into, it took me a while to become comfortable with it. I would
reccommend looking over lots of examples if you are interested in learning.

Cheers,

Dylan

--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341

2008/8/29 Dylan Beaudette <dylan.beaudette@gmail.com>:

Thanks Paolo. I'll post any new material directly in the wiki. GMT is tough to
get into, it took me a while to become comfortable with it. I would
reccommend looking over lots of examples if you are interested in learning.

I was just minutes ago talking to a friend, he was showing to me his
stuff done in GMT... really hard.
I guess I'll sometime have to learn it.

--
Paulo Marcondes = PU1/PU2PIX
-22.915 -42.224 = GG86jc