[postgis-users] Postgis Spatial Interpolation

[Jan Hartmann]

There is a second solution, PL/R: the complete R system embedded in a 
PostgreSQL server, exactly the other way round from RGdal. On Unix you 
have to compile it with PostgreSQL, about the same way as you include 
PostGIS. There are Windows executables for PostgreSQL with PostGIS and 
PostgreSQL with PL/R, but not a complete combined system, I believe, 
although that should not be difficult to produce. I do not know what is 
easier, working in the R environment and doing GIS with RGDAL, or 
working in PostGIS and doing statistics with PL/R. Probably both. I have 
done some work with PL/R, and I have been flabbergasterd (is that 
English?) with the power of such a combined system. Problem is, I just 
haven't enough time to really explore it. You need to know a little 
about many things: SQL, R, MapScript, a bit of JavaScript, and so forth, 
all quite complex languages, more complex than they look at first sight. 
I *do* know a little about all that, but then you need the time and 
concentration to actually do something useful with it. I don't think 
there is anyone near me here in Amsterdam who knows even as little as 
me, so Regina's page will really help me, there should be more of them 
(Regina's, I mean). 

Anyway, give it a try (www.joeconway.com).  Joe is one of the leading 
PostgreSQL developers, certainly on a par with Steve, Frank, Daniel and 
Paul,  and equally courteous and helpful as they always have been on his 
mailing list. I was surprised to see how small the code is, with which 
he linked those two massive Open Source packages. That alone is a 
triumph of Open Source.

Greetings from a cloudy Amsterdam (but spring is near).

Jan

Paragon Corporation wrote:
> I'm not sure if the RGDAL package would help you.
>  
> Here is a bit about it
>  
> http://www.bostongis.com/PrinterFriendly.aspx?content_name=postgresql_plr_tut03
>  
> I have a somewhat complex example that reads data from tiff files and 
> inserts into the database.  Though work on the WKT Raster project may 
> be right up your alley.
> http://postgis.refractions.net/support/wiki/index.php?WKTRasterHomePage
>  
>  
> Hope that helps,
> Regina
>
> ------------------------------------------------------------------------
> *From:* postgis-users-bounces at postgis.refractions.net 
> [mailto:postgis-users-bounces at postgis.refractions.net] *On Behalf Of 
> *Greg King
> *Sent:* Monday, March 02, 2009 5:06 PM
> *To:* postgis-users at postgis.refractions.net
> *Subject:* [postgis-users] Postgis Spatial Interpolation
>
> Hi,
>
> I'm fairly new to postgis and spatial databases but have been very 
> pleased with the results I'm getting from postgis to date.  One of my 
> projects is using postgis to load weather data from a 0.5 x 0.5 degree 
> lat/long grid.  I'm looking to  interpolate data values that fall 
> between that grid point I have values for.  A bit of googling has 
> revealed a number of applications that interface to postgis and can do 
> what I need (eg GRASS), but I don't need their full functionality or 
> the overhead of interfacing with them.  My project needs simply to 
> return interpolated values to a web page and I would rather just have 
> a pl/pgsql procedure that gives me interpolated values for a given 
> point.  My initial thoughts are to feed the necessary point data from 
> my database into a custom pl/R function and get R to interpolate the 
> data for my point.  However, that is going to involve a fair amount of 
> custom code and for me to learn more about R.  I don't want to 
> reinvent the wheel, so I'd be grateful for any thoughts on solutions 
> that meet my needs?
>
> Thanks,
>
> G
>
> PS In my googling I also saw references to PGRaster, but it looks like 
> that's still under consideration for development in postgis?
> ------------------------------------------------------------------------
>
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