[postgis-users] raster map algebra question(s)

[Bborie Park]

> I would go with storing all your like data in a single table with
> observation_date similar to what Bborie has described.
> FWIW:  The approach that Bborie has below is pretty much what
>
> ST_Union(rast,'MEAN')  does except ST_Union can do it on more than two
> rasters at a time.

I'll have to try that out!  When I wrote my half-month query, ST_Union
wasn't really ready for testing.

>
> Bborie,
>
> I am curious if you get the same answers using ST_Union as what you are
> doing. Seems like a good test to stress test ST_Union MEAN.
>

I'll do some testing after next week's upgrade of my production
databases to PostGIS trunk.

> Is your data freely downloadable from somewhere.  I was going to pull some
> from weather.gov to experiment with as I suspect moving averages will be a
> common use case and I suspect no one has tried raster in combination with
> window agg constructions. In theory it should work because all aggregates
> are supposed to work in a window agg construct without programming them to
> do so specifically.  At least as I recall all the sql aggs I've custom built
> have worked fine in window constructs.

The data used to be freely available through NASA AMES until recently.
 I plan on making the data available again some time in 2012.  If
there is anything you'd like though, let me know.

-bborie
-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu