RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Hi, They are currently writing a book that would be similar to Gslib user manual but tailored to S-GeMS features. In the meantime, you can find some help in the user manual available at http://sgems.sourceforge.net/doc/sgems_manual.pdf Cheers, Pierre Pierre Goovaerts Chief Scientist at BioMedware 516 North State Street Ann Arbor, MI 48104 Voice: (734) 913-1098 (ext. 8) Fax: (734) 913-2201 http://home.comcast.net/~goovaerts/ From: Mach Nife [mailto:[EMAIL PROTECTED] Sent: Wed 3/1/2006 3:36 PM To: Pierre Goovaerts; AI Geostats mailing list Subject: RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation It would be very nice if there would be a tutorial on how to use the variogram modeler. machnife --- Pierre Goovaerts <[EMAIL PROTECTED]> wrote: > Hi Susan, > > I would recommend the Stanford Geostatistical > Modeling Software (S-GeMS) > that is public domain and that I use in all my short > courses (some of your > colleagues have actually be trained by me). The > software can be downloaded from > http://pangea.stanford.edu/~nremy/GEMS/ > > Cheers, > > Pierre > > Pierre Goovaerts > Chief Scientist at BioMedware > 516 North State Street > Ann Arbor, MI 48104 > Voice: (734) 913-1098 (ext. 8) > Fax: (734) 913-2201 > http://home.comcast.net/~goovaerts/ > > > > From: Hohner, Susan [mailto:[EMAIL PROTECTED] > Sent: Tue 2/28/2006 1:28 PM > To: AI Geostats mailing list > Subject: RE: [ai-geostats] Re: Software for > Automatic Semivariogram Estimation > > > > Yikes! > > > > I was working through the tutorial for the > Geostatistical Analyst Extension when this email > discussion popped up. Any recommendations for a > "traditional geostatistics software package"? > > > > Thanks, > > Susan > > > > Susan Hohner, Senior Geographer > > Everglades Division, Mail Stop 4440 > > South Florida Water Management District > > 3301 Gun Club Road, West Palm Beach, FL 33406 > > (561) 682-6801 phone > > (561) 682-0100 fax > > [EMAIL PROTECTED] > > http://www.sfwmd.gov > > > > ____ > > From: Chaosheng Zhang > [mailto:[EMAIL PROTECTED] > Sent: Tuesday, February 28, 2006 12:25 PM > To: AI Geostats mailing list > Subject: Re: [ai-geostats] Re: Software for > Automatic Semivariogram Estimation > > > > Dear all, > > > > I have the same concerns with ArcGIS Geostatistical > Analyst Extension (v.9.1). I would use a traditional > geostatistics software package to fit the variogram > models in a very traditional way, and input the > parameters to ArcGIS for kriging. It seems that > ArcGIS has its own reasons to show variograms in a > non-traditional way, but I find it almost impossible > to fit the variograms mannually. You can change the > parameters, but it is very hard to see how well they > fit. By the way, you can change the lag distance or > interval in ArcGIS (it is called "lag size" there). > > > > Cheers, > > > > Chaosheng > > -- > Dr. Chaosheng Zhang > Lecturer in GIS > Department of Geography > National University of Ireland, Galway > IRELAND > Tel: +353-91-492375 > Fax: +353-91-495505 > E-mail: [EMAIL PROTECTED] > Web1: www.nuigalway.ie/geography/zhang.html > Web2: www.nuigalway.ie/geography/gis > > > > > > > > * By using the ai-geostats mailing list you agree to > follow its rules > ( see > http://www.ai-geostats.org/help_ai-geostats.htm ) > > * To unsubscribe to ai-geostats, send the following > in the subject or in the body (plain text format) of > an email message to [EMAIL PROTECTED] > > Signoff ai-geostats __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
It would be very nice if there would be a tutorial on how to use the variogram modeler. machnife --- Pierre Goovaerts <[EMAIL PROTECTED]> wrote: > Hi Susan, > > I would recommend the Stanford Geostatistical > Modeling Software (S-GeMS) > that is public domain and that I use in all my short > courses (some of your > colleagues have actually be trained by me). The > software can be downloaded from > http://pangea.stanford.edu/~nremy/GEMS/ > > Cheers, > > Pierre > > Pierre Goovaerts > Chief Scientist at BioMedware > 516 North State Street > Ann Arbor, MI 48104 > Voice: (734) 913-1098 (ext. 8) > Fax: (734) 913-2201 > http://home.comcast.net/~goovaerts/ > > > > From: Hohner, Susan [mailto:[EMAIL PROTECTED] > Sent: Tue 2/28/2006 1:28 PM > To: AI Geostats mailing list > Subject: RE: [ai-geostats] Re: Software for > Automatic Semivariogram Estimation > > > > Yikes! > > > > I was working through the tutorial for the > Geostatistical Analyst Extension when this email > discussion popped up. Any recommendations for a > "traditional geostatistics software package"? > > > > Thanks, > > Susan > > > > Susan Hohner, Senior Geographer > > Everglades Division, Mail Stop 4440 > > South Florida Water Management District > > 3301 Gun Club Road, West Palm Beach, FL 33406 > > (561) 682-6801 phone > > (561) 682-0100 fax > > [EMAIL PROTECTED] > > http://www.sfwmd.gov > > > > ________ > > From: Chaosheng Zhang > [mailto:[EMAIL PROTECTED] > Sent: Tuesday, February 28, 2006 12:25 PM > To: AI Geostats mailing list > Subject: Re: [ai-geostats] Re: Software for > Automatic Semivariogram Estimation > > > > Dear all, > > > > I have the same concerns with ArcGIS Geostatistical > Analyst Extension (v.9.1). I would use a traditional > geostatistics software package to fit the variogram > models in a very traditional way, and input the > parameters to ArcGIS for kriging. It seems that > ArcGIS has its own reasons to show variograms in a > non-traditional way, but I find it almost impossible > to fit the variograms mannually. You can change the > parameters, but it is very hard to see how well they > fit. By the way, you can change the lag distance or > interval in ArcGIS (it is called "lag size" there). > > > > Cheers, > > > > Chaosheng > > -- > Dr. Chaosheng Zhang > Lecturer in GIS > Department of Geography > National University of Ireland, Galway > IRELAND > Tel: +353-91-492375 > Fax: +353-91-495505 > E-mail: [EMAIL PROTECTED] > Web1: www.nuigalway.ie/geography/zhang.html > Web2: www.nuigalway.ie/geography/gis > > > > > > > > * By using the ai-geostats mailing list you agree to > follow its rules > ( see > http://www.ai-geostats.org/help_ai-geostats.htm ) > > * To unsubscribe to ai-geostats, send the following > in the subject or in the body (plain text format) of > an email message to [EMAIL PROTECTED] > > Signoff ai-geostats __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Hi all, for S or R users, GeoR is worth a look for auto-fitting procedures. This R package allows fitting of variograms (with the option of trend removal) via least squares (equal weights, n_pairs weights, or 'Cressie' weights), or computationally using maximum liklihood or REML. If you go for the latter you can produce profile liklihood plots for parameters etc. The package also will do most of the conventional flavors of kriging, but the main focus of the package is model based geostatistics, and is well demonstrated in: DIGGLE, P.J., RIBEIRO Jr, P.J. & CHRISTENSEN, O.F. (2003) An introduction to model based geostatistics. /In/ Möller, J. (ed) *Spatial statistics and computational methods*. Lecture notes in statistics, vol. 173, p. 43-86, Springer. The package website is here: http://www.est.ufpr.br/geoR/ and it can also be obtained from here: http://cran.r-project.org/ Hope that helps Luke begin:vcard fn:Luke Spadavecchia n:Spadavecchia;Luke org:University of Edinburgh;Biosphere Atmosphere Modelling Group adr;dom:Mayfield Rd.;;Crew Labs; Kings Buildings;Edinburgh email;internet:[EMAIL PROTECTED] tel;home:0131 5166243 x-mozilla-html:FALSE version:2.1 end:vcard * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Title: Message
Sorry.. I was meaning GeMS, not
GMES.
Gregoire
__ Gregoire Dubois (Ph.D.)
European Commission (EC)
Joint Research Centre
(JRC) WWW: http://www.ai-geostats.org
"The views expressed are purely
those of the writer and may not in any circumstances be regarded as stating an
official position of the European Commission."
-Original Message-From: Gregoire Dubois
[mailto:[EMAIL PROTECTED] Sent: 01 March 2006
09:16To: 'Hohner, Susan'Cc:
'ai-geostats@unil.ch'Subject: RE: [ai-geostats] Re: Software for
Automatic Semivariogram Estimation
GSLIB, Gstat and GMES (the last is not yet broadly used but time
will come) are free tools that can be considered nowadays as "reference
material".
Main
reason for this is that source codes are available and can be properly
checked, this is not the case for commercial packages.
...
see the software section of ai-geostats (a bit old but I will work on it
soon)
Best
regards,
Gregoire
__ Gregoire Dubois (Ph.D.)
European Commission
(EC) Joint Research
Centre (JRC) WWW:
http://www.ai-geostats.org
"The views expressed are purely
those of the writer and may not in any circumstances be regarded as stating an
official position of the European Commission."
-Original Message-From: Hohner, Susan
[mailto:[EMAIL PROTECTED] Sent: 28 February 2006
19:28To: AI Geostats mailing listSubject: RE:
[ai-geostats] Re: Software for Automatic Semivariogram
Estimation
Yikes!
I was working
through the tutorial for the Geostatistical Analyst Extension
when this email discussion popped up. Any recommendations for a
“traditional geostatistics software
package”?
Thanks,
Susan
Susan
Hohner, Senior Geographer
Everglades
Division, Mail Stop 4440
South
Florida Water Management District
3301
Gun Club Road, West
Palm Beach, FL 33406
(561)
682-6801 phone
(561)
682-0100 fax
[EMAIL PROTECTED]
http://www.sfwmd.gov
From:
Chaosheng Zhang [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 28, 2006 12:25
PMTo: AI Geostats mailing
listSubject: Re:
[ai-geostats] Re: Software for Automatic Semivariogram
Estimation
Dear
all,
I have the same concerns with
ArcGIS Geostatistical Analyst Extension (v.9.1). I would use a
traditional geostatistics software package to fit the variogram models
in a very traditional way, and input the parameters to ArcGIS for
kriging. It seems that ArcGIS has its own reasons to show variograms in
a non-traditional way, but I find it almost impossible to fit the
variograms mannually. You can change the parameters, but it is very hard to
see how well they fit. By the way, you can change the lag distance or
interval in ArcGIS (it is called "lag size"
there).
Cheers,
Chaosheng
--Dr.
Chaosheng ZhangLecturer in GISDepartment of GeographyNational
University of Ireland, GalwayIRELANDTel:
+353-91-492375Fax: +353-91-495505E-mail: [EMAIL PROTECTED]Web1:
www.nuigalway.ie/geography/zhang.htmlWeb2:
www.nuigalway.ie/geography/gis
* By using the ai-geostats mailing list you agree to follow its rules
( see http://www.ai-geostats.org/help_ai-geostats.htm )
* To unsubscribe to ai-geostats, send the following in the subject or in the
body (plain text format) of an email message to [EMAIL PROTECTED]
Signoff ai-geostats
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Title: Message GSLIB, Gstat and GMES (the last is not yet broadly used but time will come) are free tools that can be considered nowadays as "reference material". Main reason for this is that source codes are available and can be properly checked, this is not the case for commercial packages. ... see the software section of ai-geostats (a bit old but I will work on it soon) Best regards, Gregoire __ Gregoire Dubois (Ph.D.) European Commission (EC) Joint Research Centre (JRC) WWW: http://www.ai-geostats.org "The views expressed are purely those of the writer and may not in any circumstances be regarded as stating an official position of the European Commission." -Original Message-From: Hohner, Susan [mailto:[EMAIL PROTECTED] Sent: 28 February 2006 19:28To: AI Geostats mailing listSubject: RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Yikes! I was working through the tutorial for the Geostatistical Analyst Extension when this email discussion popped up. Any recommendations for a “traditional geostatistics software package”? Thanks, Susan Susan Hohner, Senior Geographer Everglades Division, Mail Stop 4440 South Florida Water Management District 3301 Gun Club Road, West Palm Beach, FL 33406 (561) 682-6801 phone (561) 682-0100 fax [EMAIL PROTECTED] http://www.sfwmd.gov From: Chaosheng Zhang [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 28, 2006 12:25 PMTo: AI Geostats mailing listSubject: Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Dear all, I have the same concerns with ArcGIS Geostatistical Analyst Extension (v.9.1). I would use a traditional geostatistics software package to fit the variogram models in a very traditional way, and input the parameters to ArcGIS for kriging. It seems that ArcGIS has its own reasons to show variograms in a non-traditional way, but I find it almost impossible to fit the variograms mannually. You can change the parameters, but it is very hard to see how well they fit. By the way, you can change the lag distance or interval in ArcGIS (it is called "lag size" there). Cheers, Chaosheng --Dr. Chaosheng ZhangLecturer in GISDepartment of GeographyNational University of Ireland, GalwayIRELANDTel: +353-91-492375Fax: +353-91-495505E-mail: [EMAIL PROTECTED]Web1: www.nuigalway.ie/geography/zhang.htmlWeb2: www.nuigalway.ie/geography/gis * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Dear Prof. Clark Here is the paper: http://www.ansinet.org/fulltext/jas/jas581405-1407.pdf Formula (4) is the weight factor. King regards. Behrang. - Original Message - From: Isobel Clark To: Behrang Kushavand Cc: AI Geostats mailing list Sent: Tuesday, February 28, 2006 9:53 PM Subject: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Behrang What weighting do you use in the weighted least squares? Isobel http://www.kriging.comBehrang Kushavand <[EMAIL PROTECTED]> wrote: hi,I have a software for Variogram AUTO Modeling (winvam) that works with gslib(GAMV.exe).First you must calculate experimental variogram (omni or directional) withgamv.exe and then by using winvam, you can fit the best model by leastsquare and weights least square criteria for given model(s),You can find it at:http://www.ai-geostats.org/software/Geostats_software/WinVAM.htmKing regards.Behrang.- Original Message -From: "Edzer J. Pebesma" <[EMAIL PROTECTED]>To: "Mach Nife" <[EMAIL PROTECTED]>Cc: "ai-geostats" Sent: Tuesday, February 28, 2006 7:59 PMSubject: Re: [ai-geostats] Software for Automatic Semivariogram Estimation> Mach Nife wrote:>> >Hi,> >> >I'm hunting for a software (freeware/openSource if> >possible), that would help estimating the best> >possible semivariogram curve in a non-interactive way.> >As an example, ArcGis Geostatistical Analyst does a> >pretty good job at this when we accept the defaults.> >It does some automatic calculations for the parameters> >of the selected model. I've tried Gstat "Fit" method> >(in the command-line version), but the results aren't> >what I expected. What I need is a command line> >software or one that can be controlled by programming.> >> >Any ideas?> >> >>> Some. I did have a look at your data, and at the> ArcGIS fit window you sent me. Clearly, we do not> fully agree on what is to be considered a "good" job.> ArcGIS calculates semivariances up to the largest> distances present in your data set; afaik the general> recommendation is not to look further than half the> longest distance (compare acf computation in time> series); the gstat default is one third the diagonal> of the area spanned. Have you tried modifying any> of these defaults? Interval widths?>> When looking at the fit, it seems that ArcGIS shows> a couple (4?) directional variograms in a single> plot, but apart from that, the sample variogram suggests> a linear model. It is obvious that fitting three parameters> (exponential model with nugget) to something that> tends to be linear will lead to problems -- an infinite> set of solutions, for instance. When you insist on> having an exponential model, you could for> instance force the range to a certain (large) value.> I suspect ArcGIS stops adjusting the range of the> exponential model when it exceeds the data extent> (Constantin, are you with us?), but should that be> considered good practice?>> My experience with automatic, general-purpose> automatic variogram fitting are not very positive;> if it were, gstat would probably have such a function.>> Are there other ai-geostats readers who have positive or> negative experiences with, or who routinely trust,> automatically fitted variograms? Which software?>> Looking forward to a heated debate,> --> Edzer>> >machnife> >> >__> >Do You Yahoo!?> >Tired of spam? Yahoo! Mail has the best spam protection around> >http://mail.yahoo.com> >> >> >> >> >> >* By using the ai-geostats mailing list you agree to follow its rules> >( see http://www.ai-geostats.org/help_ai-geostats.htm )> >> >* To unsubscribe to ai-geostats, send the following in the subject or inthe body (plain text format) of an email message to [EMAIL PROTECTED]> >> >Signoff ai-geostats> >>>>> * By using the ai-geostats mailing list you agree to follow its rules> ( see http://www.ai-geostats.org/help_ai-geostats.htm )>> * To unsubscribe to ai-geostats, send the following in the subject or inthe body (plain text format) of an email message to [EMAIL PROTEC
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Hi Susan, I would recommend the Stanford Geostatistical Modeling Software (S-GeMS) that is public domain and that I use in all my short courses (some of your colleagues have actually be trained by me). The software can be downloaded from http://pangea.stanford.edu/~nremy/GEMS/ Cheers, Pierre Pierre Goovaerts Chief Scientist at BioMedware 516 North State Street Ann Arbor, MI 48104 Voice: (734) 913-1098 (ext. 8) Fax: (734) 913-2201 http://home.comcast.net/~goovaerts/ From: Hohner, Susan [mailto:[EMAIL PROTECTED] Sent: Tue 2/28/2006 1:28 PM To: AI Geostats mailing list Subject: RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Yikes! I was working through the tutorial for the Geostatistical Analyst Extension when this email discussion popped up. Any recommendations for a "traditional geostatistics software package"? Thanks, Susan Susan Hohner, Senior Geographer Everglades Division, Mail Stop 4440 South Florida Water Management District 3301 Gun Club Road, West Palm Beach, FL 33406 (561) 682-6801 phone (561) 682-0100 fax [EMAIL PROTECTED] http://www.sfwmd.gov From: Chaosheng Zhang [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 28, 2006 12:25 PM To: AI Geostats mailing list Subject: Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Dear all, I have the same concerns with ArcGIS Geostatistical Analyst Extension (v.9.1). I would use a traditional geostatistics software package to fit the variogram models in a very traditional way, and input the parameters to ArcGIS for kriging. It seems that ArcGIS has its own reasons to show variograms in a non-traditional way, but I find it almost impossible to fit the variograms mannually. You can change the parameters, but it is very hard to see how well they fit. By the way, you can change the lag distance or interval in ArcGIS (it is called "lag size" there). Cheers, Chaosheng -- Dr. Chaosheng Zhang Lecturer in GIS Department of Geography National University of Ireland, Galway IRELAND Tel: +353-91-492375 Fax: +353-91-495505 E-mail: [EMAIL PROTECTED] Web1: www.nuigalway.ie/geography/zhang.html Web2: www.nuigalway.ie/geography/gis * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
[ai-geostats] Re: Software for Automatic Semivariogram Estimation
Ed I use the Cressie statistic to four significant figures as a guide in the interactive fitting, but generally end up using a visual judgement. It tracks as you drag the model around, so you can watch it change. I think the 'real' visual objective function is probably the perpendicular (to tangent) distance to the model line, which is effectively the combination of both gamma and h. One should then be able to alter the relative weighting between distance and height. Haven't tried this yet. Isobel http://www.kriging.com* By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Isobel Clark wrote: Behrang What weighting do you use in the weighted least squares? Isobel I have found choosing suitable weights always a frustrating event. Cressie's weights, let's say N_h/[(gamma(h))^2], has attractive properties, both intuitively and statistically. Here, gamma(h) is the model value, not the sample variogram value (because that might be zero; think of binary data). N_h is the number of point pairs used to estimate semivariance at lag (interval) h. It's downside is that while fitting the variogram, gamma(h) changes, and so the weights change. This has consequences: while fitting, the criterion you try to minimize may actually increase while the fit gets better. This is hard to deal with. If you calculate e.g. a weighted R^2, and look at the trace, it will go up, down, and then up, down, etc. The context changes. If you fix gamma(h), say to it's starting values, then the final fit may very much depend on which starting values you used. Isobel, how do you deal with this? As an alternative, (and the default value in gstat under R or S-Plus), I now tend to use N_h/h^2 [*], which is equivalent to Cressie's weights for a linear variogram with no nugget. It works often, but will give rediculusly large weight to a semivariance value with h very close to zero (think duplicate measurements). Besides these two, gstat has the options of weights N_h, and of no (=constant) weights. -- Edzer [*] If I'm correct, this was first suggested in a paper by Zhang and ... in Computers & Geosciences, early nineties. I strongly disliked it then, but consider it acquired taste. * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
RE: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Yikes! I was working through the tutorial for the Geostatistical Analyst Extension when this email discussion popped up. Any recommendations for a “traditional geostatistics software package”? Thanks, Susan Susan Hohner, Senior Geographer Everglades Division, Mail Stop 4440 South Florida Water Management District 3301 Gun Club Road, West Palm Beach, FL 33406 (561) 682-6801 phone (561) 682-0100 fax [EMAIL PROTECTED] http://www.sfwmd.gov From: Chaosheng Zhang [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 28, 2006 12:25 PM To: AI Geostats mailing list Subject: Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation Dear all, I have the same concerns with ArcGIS Geostatistical Analyst Extension (v.9.1). I would use a traditional geostatistics software package to fit the variogram models in a very traditional way, and input the parameters to ArcGIS for kriging. It seems that ArcGIS has its own reasons to show variograms in a non-traditional way, but I find it almost impossible to fit the variograms mannually. You can change the parameters, but it is very hard to see how well they fit. By the way, you can change the lag distance or interval in ArcGIS (it is called "lag size" there). Cheers, Chaosheng -- Dr. Chaosheng Zhang Lecturer in GIS Department of Geography National University of Ireland, Galway IRELAND Tel: +353-91-492375 Fax: +353-91-495505 E-mail: [EMAIL PROTECTED] Web1: www.nuigalway.ie/geography/zhang.html Web2: www.nuigalway.ie/geography/gis * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
[ai-geostats] Re: Software for Automatic Semivariogram Estimation
Behrang What weighting do you use in the weighted least squares? Isobel http://www.kriging.comBehrang Kushavand <[EMAIL PROTECTED]> wrote: hi,I have a software for Variogram AUTO Modeling (winvam) that works with gslib(GAMV.exe).First you must calculate experimental variogram (omni or directional) withgamv.exe and then by using winvam, you can fit the best model by leastsquare and weights least square criteria for given model(s),You can find it at:http://www.ai-geostats.org/software/Geostats_software/WinVAM.htmKing regards.Behrang.- Original Message -From: "Edzer J. Pebesma" <[EMAIL PROTECTED]>To: "Mach Nife" <[EMAIL PROTECTED]>Cc: "ai-geostats" Sent: Tuesday, February 28, 2006 7:59 PMSubject: Re: [ai-geostats] Software for Automatic Semivariogram Estimation> Mach Nife wrote:>> >Hi,> >> >I'm hunting for a software (freeware/openSource if> >possible), that would help estimating the best> >possible semivariogram curve in a non-interactive way.> >As an example, ArcGis Geostatistical Analyst does a> >pretty good job at this when we accept the defaults.> >It does some automatic calculations for the parameters> >of the selected model. I've tried Gstat "Fit" method> >(in the command-line version), but the results aren't> >what I expected. What I need is a command line> >software or one that can be controlled by programming.> >> >Any ideas?> >> >>> Some. I did have a look at your data, and at the> ArcGIS fit window you sent me. Clearly, we do not> fully agree on what is to be considered a "good" job.> ArcGIS calculates semivariances up to the largest> distances present in your data set; afaik the general> recommendation is not to look further than half the> longest distance (compare acf computation in time> series); the gstat default is one third the diagonal> of the area spanned. Have you tried modifying any> of these defaults? Interval widths?>> When looking at the fit, it seems that ArcGIS shows> a couple (4?) directional variograms in a single> plot, but apart from that, the sample variogram suggests> a linear model. It is obvious that fitting three parameters> (exponential model with nugget) to something that> tends to be linear will lead to problems -- an infinite> set of solutions, for instance. When you insist on> having an exponential model, you could for> instance force the range to a certain (large) value.> I suspect ArcGIS stops adjusting the range of the> exponential model when it exceeds the data extent> (Constantin, are you with us?), but should that be> considered good practice?>> My experience with automatic, general-purpose> automatic variogram fitting are not very positive;> if it were, gstat would probably have such a function.>> Are there other ai-geostats readers who have positive or> negative experiences with, or who routinely trust,> automatically fitted variograms? Which software?>> Looking forward to a heated debate,> --> Edzer>> >machnife> >> >__> >Do You Yahoo!?> >Tired of spam? Yahoo! Mail has the best spam protection around> >http://mail.yahoo.com> >> >> >> >> >> >* By using the ai-geostats mailing list you agree to follow its rules> >( see http://www.ai-geostats.org/help_ai-geostats.htm )> >> >* To unsubscribe to ai-geostats, send the following in the subject or inthe body (plain text format) of an email message to [EMAIL PROTECTED]> >> >Signoff ai-geostats> > * By using the ai-geostats mailing list you agree to follow its rules> ( see http://www.ai-geostats.org/help_ai-geostats.htm )>> * To unsubscribe to ai-geostats, send the following in the subject or inthe body (plain text format) of an email message to [EMAIL PROTECTED]>> Signoff ai-geostats * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
Re: [ai-geostats] Re: Software for Automatic Semivariogram Estimation
Dear all, I have the same concerns with ArcGIS Geostatistical Analyst Extension (v.9.1). I would use a traditional geostatistics software package to fit the variogram models in a very traditional way, and input the parameters to ArcGIS for kriging. It seems that ArcGIS has its own reasons to show variograms in a non-traditional way, but I find it almost impossible to fit the variograms mannually. You can change the parameters, but it is very hard to see how well they fit. By the way, you can change the lag distance or interval in ArcGIS (it is called "lag size" there). Cheers, Chaosheng --Dr. Chaosheng ZhangLecturer in GISDepartment of GeographyNational University of Ireland, GalwayIRELANDTel: +353-91-492375Fax: +353-91-495505E-mail: [EMAIL PROTECTED]Web1: www.nuigalway.ie/geography/zhang.htmlWeb2: www.nuigalway.ie/geography/gis * By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
[ai-geostats] Re: Software for Automatic Semivariogram Estimation
Hi All It is difficult to have an automatic best fit semi-variogram until you define what you mean by "best fit". Noel Cressie's goodness of fit statistic goes a long way towards the ideal, but is very insensitive to changes in nugget effect and pretty insensitive to fairly large changes in the ranges. Optimal Cressie fits aren't always optimal visually, either. None of the automated methods I've heard of will choose the type of semi-variogram model and/or the number of nested components. Or anisotropy for the most part. As Ed says, if we knew the criteria we'd all write software for it (and retire!). I also look forward to varied opinions. Semi-variogram fitting is one of the most subjective stages of a geostatistical analysis. Isobel http://www.kriging.com* By using the ai-geostats mailing list you agree to follow its rules ( see http://www.ai-geostats.org/help_ai-geostats.htm ) * To unsubscribe to ai-geostats, send the following in the subject or in the body (plain text format) of an email message to [EMAIL PROTECTED] Signoff ai-geostats
