ehizcara@agrogex.com wrote:
Eduardo, thanks a lot. Before I decide what will I use - what about applying
fault lines? Is it possible to incorporate those as lines where stops
interpolations?
The only FOSS I know that supports fault lines (if that's what you
mean) is Surfit http://surfit.sourceforge.net
Examples: http://surfit.sourceforge.net/surfit/examples.html.
Maciek
Maciej Sieczka wrote on 09/25/2006 12:12 PM:
ehizcara@agrogex.com wrote:
Eduardo, thanks a lot. Before I decide what will I use - what about applying
fault lines? Is it possible to incorporate those as lines where stops
interpolations?
The only FOSS I know that supports fault lines (if that's what you
mean) is Surfit http://surfit.sourceforge.netExamples: http://surfit.sourceforge.net/surfit/examples.html.
Maciek
Luckily GRASS can do that, too:
http://mpa.itc.it/markus/grass61/demos/gully_surf_rst.jpg
... taken from our GRASS book,
section 7.3.5 Surfaces with faults.
(if you have the 1st edition, see also related erratum:
http://mpa.itc.it/grasstutor/errata_menu.phtml)
Cheers
Markus
Markus Neteler wrote:
Maciej Sieczka wrote on 09/25/2006 12:12 PM:
ehizcara@agrogex.com wrote:
Eduardo, thanks a lot. Before I decide what will I use - what about applying
fault lines? Is it possible to incorporate those as lines where stops
interpolations?
The only FOSS I know that supports fault lines (if that's what you
mean) is Surfit http://surfit.sourceforge.netExamples: http://surfit.sourceforge.net/surfit/examples.html.
Maciek
Luckily GRASS can do that, too:
http://mpa.itc.it/markus/grass61/demos/gully_surf_rst.jpg
.. taken from our GRASS book,
section 7.3.5 Surfaces with faults.
Markus,
That's not the same. I don't you can achieve this:
http://surfit.sourceforge.net/surfit/fault_8tcl-example.html
http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.html
using Grass. In Grass you can't use lines as interpolation faults. The
method you refer to uses area masking, and it can't reproduce the
Surfit examples.
Maciek
Hi Maciek,
I will disagree with You - as
http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.html says:
"The main idea of fault curves is that parts of resulting surface between
fault curve are independent of each other."
It's like masking areas between fault lines, interpolating them seperatly and
patching together. Only difference - in GRASS you must do it manualy for each
fault-enclosed area.
Maris.
On Monday 25 September 2006 15:35, Maciej Sieczka wrote:
Markus,
That's not the same. I don't you can achieve this:
http://surfit.sourceforge.net/surfit/fault_8tcl-example.html
http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.htmlusing Grass. In Grass you can't use lines as interpolation faults. The
method you refer to uses area masking, and it can't reproduce the
Surfit examples.Maciek
Māris Nartišs wrote:
Hi Maciek,
I will disagree with You - as
http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.html says:
"The main idea of fault curves is that parts of resulting surface between
fault curve are independent of each other."
It's like masking areas between fault lines, interpolating them seperatly and
patching together. Only difference - in GRASS you must do it manualy for each
fault-enclosed area.
Māris,
OK, I don't know anything about Surfit, so maybe I shouldn't argue. But
I'll tease it for fun :). Please, tell me how you think it is possible
to reproduce the effect of the fault line in the center of the image at:
http://surfit.sourceforge.net/surfit/fault_8tcl-example.html
by "masking areas between fault lines, interpolating them seperatly and
patching together".
This fault line there makes the surface discontinuos only on that
limited distance where it's present, accross a single, consistent area.
I can't imagine how I would achieve the same interpolating separate
areas and merging them afterwards.
Also mind the shorter fault line here:
http://surfit.sourceforge.net/surfit/trend_8tcl-example.html
What do you think now?
Maciek
Hi Maris,
Using interpolation breaklines (in the actual discussion, 'faults') does not provide the same results as patching two partly-masked interpolations. Do no forget breaklines can be non-strait complex curves, that's why is does not give you the same results as using masks.
Say you have:
xxxxx
xxoxx
x1o2x
ooooo
where o = land, your breakline, and x = water. 1 and 2 are two 'x' water points. When masking land 'o' and interpolating, 1 and 2 will influence each side of the land arm (the 'o' land that goes north) while they shouldn't since there is land between them. I do not know the exact algorythm, but this can't happen when using breaklines. I hope this example I was clear enough to convince you the result of masks and breaklines is not the same... 
Cheers,
Alex
MÄris NartiÅ¡s wrote:
Hi Maciek,
I will disagree with You - as http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.html says:
"The main idea of fault curves is that parts of resulting surface between fault curve are independent of each other." It's like masking areas between fault lines, interpolating them seperatly and patching together. Only difference - in GRASS you must do it manualy for each fault-enclosed area.Maris.
On Monday 25 September 2006 15:35, Maciej Sieczka wrote:
Markus,
That's not the same. I don't you can achieve this:
http://surfit.sourceforge.net/surfit/fault_8tcl-example.html
http://surfit.sourceforge.net/surfit/fault__approx_8tcl-example.htmlusing Grass. In Grass you can't use lines as interpolation faults. The
method you refer to uses area masking, and it can't reproduce the
Surfit examples.Maciek
--
Alexandre Leroux, M.Sc., Ing.
Environnement Canada / Environment Canada
Centre météorologique canadien / Canadian Meteorological Centre
Division de la réponse aux urgences environnementales /
Environmental Emergency Response Division
alexandre.leroux@ec.gc.ca
