[Qgis-developer] Kriging interpolation functionality in QGIS?

[Stefan Keller]

Werner: I'm with you.
Victor: Thanks for the pointer to SAGA tools in Processing.

The background of my questions is, that I'm having a research project
in mind where we need to implement Kriging for predefined agricultural
soil samples.
Here the farmer does not need to know what's under the hood.
Now I'm thinking to give back something to the QGIS community like
parameter suggestions calculated from cross validation.
And I'm reluctant to implement this using something other than a QGIS
extension (nothing against SAGA).

Any one who has experiences on how estimate any Kriging parameters?
E.g. these SAGA tool parameters look especially "frightening" :-)
Power function A/B (in Universal K.) and Variogram Model (in Ordinary K.)

:Stefan

2015-09-28 21:36 GMT+02:00 Werner Macho <werner.macho at gmail.com>:
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> Hi Stefan,
>
> My post was in no way meant offending. I replied to Victor and Barry
> just because of the nice joke about "wizards".
> My experience at university is just that a lot of students use
> "wizards" without knowing what they are doing and Barrys post
> described exactly what I saw at university.
>
> I hope you will find (or already found) what you are looking for.
> With Kriging unfortunately I cannot help you because I just did not
> understand it ;)
>
> regards,
> Werner
>
> On 28/09/15 20:32, Stefan Keller wrote:
>> Werner, Barry
>>
>> I just wrote to have Kriging in QGIS with less external
>> *dependencies* like GRASS, SAGA (or R). That's what I meant by
>> "easier to use" in my initial thread.
>>
>> Then I challenged the benefit of Kriging versus IDW just because I
>> don't want to use it because it's cool. Thanks to Barry and others
>> for the explanations.
>>
>> The use case you obviously have in mind, is to do data analytics as
>> a researcher or informed user - which requires the steps Sjur
>> mentioned (many thanks too).
>>
>> On the other hand, to me it's still worth thinking of a helper
>> dialog (in whatever implementation and whatever you call it) which
>> suggests parameters calculated on cross validation.
>>
>> ... Unless you are saying that only statisticians can ever master
>> Kriging :-O
>>
>> :Stefan
>>
>>
>>
>> 2015-09-28 17:34 GMT+02:00 Werner Macho <werner.macho at gmail.com>:
>>> Well written and I fully support that. Sometimes it seems that
>>> people want a wizard for everything (and a computer that can read
>>> their mind). I am against imitating everything that "commercial
>>> software" provides. Sometimes it is better to treat users to
>>> switch on their brain. For me that is still the point that
>>> separates Opensource Software from proprietary one. I am not sure
>>> if we should try to get more users at all cost. Let's do things
>>> correct - even if that is not always popular (because it is not
>>> in reach with one click).
>>>
>>> just my 2c Werner
>>>
>>> On Mon, Sep 28, 2015 at 1:37 PM, Barry Rowlingson
>>> <b.rowlingson at lancaster.ac.uk> wrote:
>>>> On Mon, Sep 28, 2015 at 10:35 AM, Victor Olaya
>>>> <volayaf at gmail.com> wrote:
>>>>
>>>>> From the point of view of user-friendliness, the Processing
>>>>> implementation (wrapping the corresponding SAGA modules),
>>>>> might not be as easy to use as some people would like, but
>>>>> for tools such as kriging I am strongly against wizard-like
>>>>> UI's and similar elements. ArcGIS's Statistical Analyst is
>>>>> great and has a wizard with a fantastic "next" button that
>>>>> allows you to interpolate using all sort of esoteric methods
>>>>> and will make you believe that you are creating sound raster
>>>>> layers...when the truth is that, without knowledge, you are
>>>>> creating rubish. I don't like to give users that wrong
>>>>> sensation.
>>>>
>>>> Agreed. Anything claiming to be a "wizard" for Kriging really
>>>> needs to be a psychic wizard that can read your thoughts and
>>>> understand your data. A better device would be an
>>>> "Interrogator":
>>>>
>>>> *ping* Your data seems to be discrete small integers, are you
>>>> sure you want to model it as a Gaussian? [*yes*/no]
>>>>
>>>> *ping* So you want to model your data with Gaussian cofactor
>>>> response p-value thresholds from an underlying Bayesian
>>>> surface? [*yes*/no]
>>>>
>>>> *ping* That last question was nonsense. You're just clicking
>>>> "yes" until you get a surface model - any surface model -
>>>> right? [*yes*/no]
>>>>
>>>> *ping* okay, at least you are honest. I'm deleting the kriging
>>>> module now, go find a statistician.
>>>>
>>>> Barry _______________________________________________
>>>> Qgis-developer mailing list Qgis-developer at lists.osgeo.org
>>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>> _______________________________________________ Qgis-developer
>>> mailing list Qgis-developer at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
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