[postgis-users] ST_AsRaster and gdal_translate

[Bborie Park]

For exporting, instead of using the rasters in
"bdtq_20k_hydro_so_gfsm_aea_subset_1000m", you may want to try something
like...

CREATE TABLE foo AS
SELECT 1 AS rid, ST_AsRaster((
	SELECT
		ST_Collect(geom)
	FROM hydrology.bdtq_20k_hydro_so_gfsm_aea_subset
), 1000.0, 1000.0
) AS rast

The above creates one raster using the collection of geometries, which
can then be exported with gdal_translate.

-bborie

On 07/25/2012 12:57 PM, Guillaume Drolet DRF wrote:
> Hi,
> 
> I have been struggling with this since yesterday and now I think it is
> time for me to request some help from the community :
> 
> I am trying to convert a geometry table (polygons) to a raster that will
> have 1000 m-pixels, and then export that raster to a TIF file using
> gdal_translate.
> I've tried loads of different queries but nothing seems to work... Here
> are examples of some the queries I tried:
> 
> CREATE TABLE rasters.bdtq_20k_hydro_so_gfsm_aea_subset_1000m AS
>     SELECT ST_AsRaster(hyd.geom, 1000.0, 1000.0) AS rast
>     FROM hydrology.bdtq_20k_hydro_so_gfsm_aea_subset AS hyd;
> 
> ALTER TABLE rasters.bdtq_20k_hydro_so_gfsm_aea_subset_1000m ADD COLUMN
> rid serial PRIMARY KEY;
> 
> CREATE INDEX
>     ON rasters.bdtq_20k_hydro_so_gfsm_aea_subset_1000m
>     USING gist(st_convexhull(rast));
> 
> SELECT AddRasterConstraints('rasters'::name,
>         'bdtq_20k_hydro_so_gfsm_aea_subset_1000m'::name,
>         'rast'::name);
> 
> Then at the command line:
> 
>>gdal_translate "PG:host=localhost port=5432 dbname=testspdb
> user=postgres password=*** schema=rasters
> table=bdtq_20k_hydro_so_gfsm_aea_subset_1000m mode=2"
> E:\temp\hydro1000m.tif
> 
> I get this error:
> 
> ERROR 1: Error, the table
> rasters.bdtq_20k_hydro_so_gfsm_aea_subset_1000m contains tiles with
> different size, and irregular blocking is not supported yet
> GDALOpen failed - 1
> Error, the table rasters.bdtq_20k_hydro_so_gfsm_aea_subset_1000m
> contains tiles
> with different size, and irregular blocking is not supported yet
> 
> My problem seems to be related to the irregular blocking of my raster. I
> though I could create a raster with regular block and pixel size but I
> didn't figure how to do this yet. I tried to achieve this by creating an
> empty raster:
> 
> CREATE TABLE rasters.test_rasterize (
>     rid serial PRIMARY KEY,
>     rast raster
> );
> 
> INSERT INTO rasters.test_rasterize VALUES (
>     1,
>     ST_MakeEmptyRaster(45, 62, 1828552.00, 1422569.00, 1000.0, 1000.0,
> 0.0, 0.0, 3175)
> );
> -- 45 and 62 are the approximate numbers of 1000 m pixels in x and y
> that fit inside the extent of my geometry layer
> UPDATE rasters.test_rasterize
>     SET rast = ST_AsRaster(geom, 1000.0, 1000.0)
>         FROM hydrology.bdtq_20k_hydro_so_gfsm_aea_subset;
> 
> 
> When I call gdal_translate with rasters.test_rasterize, I get this:
> 
> Input file size is 2, 4
> 0...10...20...30...40...50...60...70...80...90...100 - done.
> 
> I'm getting desperate and will greatly appreciate any hints!
> 
> If that can help, I'm using PostGIS 2.0.0 r9605 and GDAL 1.9.0
> 
> Many thanks,
> 
> Guillaume
> 
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> 

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