[postgis-users] Postgis Spatial Interpolation

Stephen Woodbridge woodbri at swoodbridge.com
Mon Mar 2 14:52:34 PST 2009

Greg King wrote:
> 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?

Hi Greg,

There a bunch of people here that can probably help. If you had a 
working function what would be some sample input and output you would 
expect and describe the process of computing it. We can probably work 
out the details of the math and code a pl/pgsql function.


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