Thanks for the suggestion, Pierre. I turned out to be a mistake on my part as I used the first Albers Equal Area Conic listing I found on http://spatialreference.org. It turns out there are two..... ESRI:102003 <http://spatialreference.org/ref/esri/102003/>: USA Contiguous Albers Equal Area Conic ESRI:102008 <http://spatialreference.org/ref/esri/102008/>: North America Albers Equal Area Conic
-David On Thu, Feb 9, 2012 at 12:16 PM, Pierre Racine <pierre.rac...@sbf.ulaval.ca>wrote: > I generally display things in OpenJump to make sure they align correctly > before doing anything instead of assuming they do. Do the projected > geometries align properly with the rasters? > > You can display the raster extents easily in OpenJump by casting the > raster to geometry (rast::geometry)... > > You can also do this easily in QGIS or ArcGIS 10. > > Pierre > > > -----Original Message----- > > From: postgis-users-boun...@postgis.refractions.net [mailto: > postgis-users- > > boun...@postgis.refractions.net] On Behalf Of David Quinn > > Sent: Thursday, February 09, 2012 10:45 AM > > To: PostGIS Users Discussion > > Subject: [postgis-users] Question about using ST_Transform() > > > > Hello All, > > > > I'm trying to understand how to use ST_Transform() on a query. When I > have > > everything in the same projection (in this case Albers Equal Area Conic) > my query > > returns the correct result: > > > > SELECT > > SUM((stats).sum) > > FROM ( > > select > > ST_SummaryStats(ST_Clip(r.rast, 1, p.geom, NULL, TRUE)) as stats > > FROM > > ny_albers as r, > > cities_albers as p > > WHERE > > p.name = 'new_york' > > AND > > ST_Intersects(r.rast, p.geom) > > ) as foo; > > > > If I use a table with polygons in a different projection (in this case > Web > > Mercator), I do not get any values returned: > > > > SELECT > > SUM((stats).sum) > > FROM ( > > select > > ST_SummaryStats(ST_Clip(r.rast, 1, ST_Transform(p.geom,102003), > NULL, > > TRUE)) as stats > > FROM > > ny_albers as r, > > cities_webMercator as p > > WHERE > > p.name = 'new_york' > > AND > > ST_Intersects(r.rast, ST_Transform(p.geom,102003)) > > ) as foo; > > > > I added the projection SRID:102003 using the following lines: > > > > INSERT into > > spatial_ref_sys ( > > srid, > > auth_name, > > auth_srid, > > srtext, > > proj4text > > ) > > values ( > > 102003, -- I changed this line as it was originally 9102003 which > did not satisfy > > the constraints > > 'esri', > > 102003, > > 'PROJCS["USA_Contiguous_Albers_Equal_Area_Conic",GEOGCS["GCS_North_A > > merican_1983",DATUM["North_American_Datum_1983",SPHEROID["GRS_1980 > > ",6378137,298.257222101]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453 > > 292519943295]],PROJECTION["Albers_Conic_Equal_Area"],PARAMETER["False_ > > Easting",0],PARAMETER["False_Northing",0],PARAMETER["longitude_of_center > > ",- > > 96],PARAMETER["Standard_Parallel_1",29.5],PARAMETER["Standard_Parallel_2 > > ",45.5],PARAMETER["latitude_of_center",37.5],UNIT["Meter",1],AUTHORITY["E > > PSG","102003"]]', > > '+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=37.5 +lon_0=-96 +x_0=0 > +y_0=0 > > +ellps=GRS80 +datum=NAD83 +units=m +no_defs '); > > > > I had some problems when I tried to add this projection from > > http://spatialreference.org/ref/esri/102003/postgis/ > > The names and values of srtext, and proj4text were reversed, and the SRID > > seemed incorrect so I changed it. I don't know if this is related to my > question > > above, but I thought it worth mentioning. I did import the raster and > polygon > > using this SRID on the query that worked. > > > > Thank you, > > David > > > > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users >
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