[postgis-users] Raster Points in Polygon (was Re: PostGIS Raster for Met Data)

[Michael Akinde]

Hi,

Sounds interesting. Is your code online anywhere?

All of our source code is GPL and available at https://github.com/wdb. WDB is the backend database server for yr.no, Norway's largest weather site with ~3M visitors a week. It's heavily optimized for point retrieval from grids - which it does very effectively (an average yr.no weather page retrieves approximately 3000 points in <0.2s). We also recently implemented a NetCDF-Java interface to the database, to facilitate easy link up with WMS services (at least in theory).

Our plan now is to extend and optimize the functionality for polygon retrieval and point data, since the system is getting leveraged for a variety of different types of projects.

I don't think we'll be moving our data into PostGIS rasters (our experiments so far haven't shown any encouraging results performance-wise - perhaps not surprising, given that our current algorithms is essentially C code working on flat-files); but I hope that we can leverage the algorithms discussed in the thread to do the geo-spatial calculations for the more nasty queries using PostGIS. Pierre was kind enough to demonstrate that it can be done fairly easily - now I just have to figure out how to do it efficiently enough that our users will be happy.

st_intersect(raster, raster) sounds very interesting, but what would be the result from the function?

Regards,

Michael A.

----- Original Message -----
> Hey Michael,
> 
> I do something similar with meteorological/climate (temperature,
> precipication, ndvi, gpp) datasets but the raw data is stored in
> rasters
> (one image per day per variable) for 50+ years. In the current system,
> the rasters are stored as massive tables with each row containing the
> observation date, grid cell value and grid cell coordinates. I'm in
> the
> process of testing the performance and storage requirements of PostGIS
> Raster with a subset of the rasters for a variety of tile sizes. I
> expect that I'll be moving over to using PostGIS Raster by the end of
> this year.
> 
> I plan on writing a two raster ST_Intersects(raster, raster) function
> as
> PostGIS Raster currently only has ST_Intersects(raster, geometry). The
> additional hope is that I can get the two raster ST_MapAlgebra(raster,
> raster) done by the time PostGIS 2.0 is branched.
> 
> -bborie
> 
> --
> Bborie Park
> Programmer
> Center for Vectorborne Diseases
> UC Davis
> 530-752-8380
> bkpark at ucdavis.edu
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