[R-sig-Geo] Best approach to implement Spatial Interpolations

[Thomas Adams]

Edzer,

Not to deflate Cesar's project, but from our past email exchanges you 
are aware that I have been very pleased with the standalone version of 
your gstat program and feel that it interfaces wonderfully with GRASS 
6.x; I would highly recommend this approach to anyone. Also, for those 
who may not be aware, use of the R gstat package is usable with GRASS 
GIS as well. This is not to say that the gstat-GRASS interface employs a 
modern GUI; it does not, but the interface is straightforward and very 
usable.

I also look forward to seeing the results of Cesar's development project.

Regards,
Tom


Edzer J. Pebesma wrote:
> Cesar Martinez Izquierdo wrote:
>   
>> Hello list,
>> we are trying to implement spatial interpolations (IDW and several types 
>> of  Kriging) in our open source GIS application, which is written in Java.
>>
>> We plan to use JRI to connect with R from Java, and then use the 
>> features of "gstat" R-package to calculate the interpolations.
>>
>> However, we don't want R to draw the results of interpolations, we just 
>> want to get the raw result which we will draw in our GIS client.
>>
>> Now, the questions:
>> - Do you think gstat is the best R package for this task?
>>   
>>     
> As the author, I will refrain from commenting on this. It has a large 
> user base, a code that has been open source and stable for a long time, 
> and it has several options not found in other packages, notably block 
> kriging, cokriging, and kriging in a local neighbourhood with an 
> efficient search algorithm (quadtrees) for huge/massive data sets.
>   
>> I've read that it doesn't allow not-projected data. Is there a package 
>> which provides similar algorithms and works with not-projected data?
>>   
>>     
> Recently, this functionality has been added, only the quadtree algorithm 
> does not work in this case; I'm still in doubt whether quadtrees are 
> useful on a sphere. Consider this code somewhat experimental, but I'm 
> willing to help debug it if needed. It does, for example not check 
> whether covariance functions provided are positive definite on a sphere, 
> and has little (if any) functions specifically dedicated for this 
> purpose. It does compute great circle distances though.
>
> Another package that seems to deal with unprojected coordinates that you 
> may want to look into is package fields.
>   
>> - Do you have some documentation regarding this topics (more exactly: 
>> documentation about how to get the results of a kriging, etc with JRI)?
>>
>>   
>>     
> Perhaps the JGR user interface is an example?
>
> I'm very interested in your developments and experiences; please keep 
> me/us updated on this mailing list.
> --
> Edzer
>   
>> Any comments and suggestions are welcome.
>>
>> Regards,
>>
>>
>>     
>
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>   


-- 
Thomas E Adams
National Weather Service
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