[R-sig-Geo] Weird experimental 3D spatiotemporal variogram

[Edzer Pebesma]

Thanks Piero; this report revealed a bug in the gstat spatio-temporal
variogram computation, which should be fixed in the development version.
gstat source code has move to r-forge, development binaries can be
downloaded from https://r-forge.r-project.org/projects/gstat/


On 01/15/2013 04:09 PM, Piero Campalani wrote:
> Edzer, Ben,
> (I was missing the vignette on spatio-temporal analysis with gstat.. !!)
> 
> I'm attaching a clearer figure of the experimental variogram: the /origin/
> at 0 spatio-temporal lag is not zero actually.
> 
> Yes, I am using **variogramST** on a STFDF: the spacetime object looks ok,
> then I simply call:
>> variogramST(pm~1, mySTFDF, tlags=0:6)
> 
> Ben, out of band I can give you my .Rdata cutout with the STFDF if you're
> interested.
> (It seems from the ST vignette that `variogramST` is now merged into
> `variogram` ?)
> 
> --------------------------
>> R.version.string
> [1] "R Under development (unstable) (2012-10-03 r60866)"
> --------------------------
> 
> Thanks,
> Piero
> 
> On 15 January 2013 15:15, Benedikt Gräler <ben.graeler at uni-muenster.de>wrote:
> 
>> Dear Piero,
>>
>> how did you compute these variograms, using variogramST in gstat (which
>> version?)?
>>
>> Figures 4-7 in gstat's vignette "Spatio-temporal geostatistics using
>> gstat" on CRAN show the missing value for the zero temporal and zero
>> spatial lag class. I could not identify this property in your wireframe
>> plots.
>>
>> To me, the temporal effect looks like being "upside-down". I'll be happy
>> to take a quick look at your script/data in case your problem still remains.
>>
>> Best,
>>
>>  Ben
>>
>>
>>
>>
>> On 15.01.2013 11:51, Edzer Pebesma wrote:
>>
>>> Piero,
>>>
>>> from the orientation of your graph, I could not see very well what
>>> happens at zero-time, zero-space lag.
>>>
>>> Did you compute a pure-time variogram, i.e. with zero space distance?
>>> This one should have a missing zero-value, unless you have duplicate
>>> measurements.
>>>
>>> On 01/10/2013 03:20 PM, Piero Campalani wrote:
>>>
>>>> Dear list,
>>>>
>>>> I am predicting PM measurements on a spatiotemporal grid with monthly
>>>> intervals in time.
>>>> At modeling time, I am looking at the experimental 3D variograms
>>>> (`wireframes`) but I see that weird decreasing behavior in time (see
>>>> wireframes_2008-1.eps for January 2008): there is a peak at 0 time lags,
>>>> then correlation in time is much higher over different days.
>>>> How can I interpret such variogram?
>>>> Would it mean that there is a very high spatial variability for values on
>>>> the same day, whereas temporal variability is significantly lower?
>>>>
>>>> Thanks for any hint,
>>>> (I can provide implementation details in case of need)
>>>>
>>>> Piero
>>>>
>>>>
>>>>
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>>>>
>>>>
>>>
>> --
>> Benedikt Gräler
>>
>> ifgi - Institute for Geoinformatics
>> University of Muenster
>>
>> http://ifgi.uni-muenster.de/**graeler<http://ifgi.uni-muenster.de/graeler>
>>
>> Phone: +49 251 83-33082
>> Mail: ben.graeler at uni-muenster.de
>>
>>
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> 
> 
> 
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de