[postgis-users] PostGIS WKT Raster

Pierre Racine Pierre.Racine at sbf.ulaval.ca
Mon Jul 14 13:54:58 PDT 2008

>Not sure where Paul is lurking these days, but I wanted to throw out
>the name of an application that can already do half of what Pierre is
>looking for: StarSpan.
>This is the tool I use when ever I need to fuse raster with vector
>data. Since it can use GDAL/OGR datatypes, it is possible to run
>against PostGIS data directly. I commonly use it to cross postgis data
>with rasters stored in GRASS.

Thanks for the suggestion Dylan.

I didn't really consider StarSpan for some reasons:

-I must run it as a (web) server. I could fork a new instance of it for
each query but I don't really like that.
-I must also "extract" information from vector layer. I don't like the
idea of having one piece of (C?) code for vector/raster extraction and
another one (SQL) for vector/vector extraction (using PostGIS).
Vector/vector extraction is commonly done with intersection. The only
piece missing was vector/raster intersection. This is why I came with
the conclusion that I need raster integration in PostGIS. This is
without speaking about the solution this bring to other raster/vector
analysis problems.
-Could StarSpan do it on a Canada wide tiled landsat coverage? I would
probably have to write indexing code to avoid that StarSpan tries to
extract pixel where vector do not intersect. The strenght of doing this
in PostGIS is that it has all the stuff needed to implement large
indexed/tiled coverage. It can do the job little by little without
having to load a 2 GB raster...
-Unfortunately, as you said, it would not do all the other interesting
raster operations.


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