Re: Postgis Spatial Interpolation
Jan Hartmann <j.l.h.hartmann <at> uva.nl>
2009-03-03 16:47:28 GMT
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
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.
Hope that helps,
Regina
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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