[postgis-users] Mapserver/Postgis connection and WMS query

[David Quinn]

Pierre,

What do you mean by reading the raster layer as a GDAL layer? In the
PostGIS in Action raster example it seemed to just connect to the database,
with no query using :

Data "PG:host=localhost ....."

I tried removing CONNECTION and DATA and using the following:

DATA "PG:host=18.00.00.00 dbname=raster_analysis user=postgres port=5434
password=password schema='myschema' table='pop_800'"

This did not work either. Should I be just connecting to the data, and not
trying to have a query there also?

-David

On Thu, Feb 16, 2012 at 3:31 PM, Pierre Racine
<Pierre.Racine at sbf.ulaval.ca>wrote:

> From what I know there is no way this should work. You have to read the
> raster layer as a GDAL layer. This is what is done in PostGIS in Action.
>
> Pierre
>
> > -----Original Message-----
> > From: postgis-users-bounces at postgis.refractions.net [mailto:
> postgis-users-
> > bounces at postgis.refractions.net] On Behalf Of David Quinn
> > Sent: Thursday, February 16, 2012 3:14 PM
> > To: PostGIS Users Discussion
> > Subject: [postgis-users] Mapserver/Postgis connection and WMS query
> >
> > Hi List,
> >
> > (I did send a very similar question to the mapserver list two days ago
> but I didn't
> > hear any comments or suggestions. This is a problem between mapserver and
> > postgis).
> >
> > I'm using mapserver to display some rasters as WMS layers using
> Openlayers. At
> > the moment I have all my rasters in a web-readable folder and it works
> fine. I
> > want to try accessing the rasters using postgis, but I'm not sure
> exactly how to
> > do this. I've read through this
> http://mapserver.org/input/vector/postgis.html
> > and the relevant part of PostGIS in Action. My original map file (which
> worked)
> > looked like this:
> >
> > LAYER
> > NAME "new_york_pop"
> > DATA    "/home//htdocs/data/new_york_pop.tif"
> > STATUS  OFF
> > TYPE    RASTER
> > METADATA
> > "wms_title"  "WMS new_york Raster"
> > "wms_srs"    "EPSG:900913"
> > END
> > END
> >
> > I tried changing this to the following:
> >
> > LAYER
> > NAME "new_york_pop"
> > TYPE    RASTER
> > CONNECTIONTYPE POSTGIS
> > CONNECTION "host=18.00.00.00 dbname=raster_analysis user=postgres
> > password=mypassword port=5434"
> > DATA "SELECT ST_AsTIFF(ST_Clip(r.rast, 1, p.geom, NULL, TRUE)) FROM
> > us_pop_800 AS r, cities AS p WHERE ST_Intersects(r.rast,  p.geom) AND
> p.name
> > = 'new_york'"
> > STATUS  OFF
> > METADATA
> > "wms_title"  "WMS new_york Raster"
> > "wms_srs"    "EPSG:900913"
> > END
> > END
> >
> > I want to clip my raster to the polygon and to display the clipped
> raster using a
> > WMS query. The SQL query runs fine within the SQL console of Postgresql
> and
> > returns a few tiffs, but it does not work on mapserver. My mapserver
> error log
> > shows the following:
> >
> > [Tue Feb 14 12:16:29 2012].918681 msDrawMap(): Image handling error.
> Failed
> > to draw layer named 'new_york_pop'.
> > [Tue Feb 14 12:16:29 2012].917535 msDrawMap(): rendering using
> > outputformat named png (AGG/PNG).
> > [Tue Feb 14 12:16:29 2012].918757 msDrawRasterLayerLow(): Unable to
> access
> > file. Corrupt, empty or missing file 'SELECT ST_AsTIFF(ST_Clip(r.rast,
> 1, p.geom,
> > NULL, TRUE)) FROM us_pop_raster AS r, cities AS p WHERE
> ST_Intersects(r.rast,
> > p.geom) AND p.name = 'new_york'' for layer 'new_york_pop'.
> > [Tue Feb 14 12:16:29 2012].918766 msDrawMap(): Image handling error.
> Failed
> > to draw layer named 'new_york_pop'.
> >
> > I would appreciate any suggestions for debugging this. I have connected
> to the
> > postgresql database using a php file from the same location so mapserver
> > should have the correct permissions to connect (and my port is 5434,
> rather than
> > the usual 5432).
> >
> > Thank you,
> > David
>
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