Create a PostGIS raster using GDAL and Python?

Question

I'd like to create a PostGIS raster using GDAL and python.

I can get the driver easily:

drv = gdal.GetDriverByName("PostGISRaster")

But how can I create a new raster table? I can't find any information about drv.Create to explain what to put there....?

Answer 1

It looks like the ability to create rasters is not yet available in the driver. However, you can create a layer using your standard PostgreSQL Python driver (i.e. psycopg2) and then open it from GDAL.

So you'd create a layer using ST_MakeEmptyRaster and ST_AddBand:

CREATE TABLE rtest (gid serial primary key, rast raster);
INSERT INTO rtest (rast) VALUES (ST_AddBand(ST_MakeEmptyRaster(100, 100, 1, 1, 2), '8BUI'::text));

Then you'd open and manipulate the raster in GDAL/Python

ds = gdal.Open('PG:host=localhost dbname=mydb table=rtest user=myuser')

I haven't tested this extensively yet, but it (削除) seems to work. (削除ここまで) doesn't work at all. I get the error,

Writing through PostGIS Raster band not supported yet

when I try to write.

You could use Python and psycopg2 to write chunks of your image to a raster table using ST_SetValues.

• James: yeah...but you wouldn't be able to write pixel values to the raster (without explicitly using postgis functions), right?
• Rob Skelly: Hah, you're right. I didn't test that one crucial step. Made a small edit to my answer to reflect that.

Answer 2

Recently came across this and it ended up helping me, so I thought I would share an update.

Adding additional arguments help as well as adding raster constraints to the table you are trying to use.

ds = gdal.Open('PG:host='' dbname='' schema='' table='' user='' port='' password='' column='' mode=2')
SELECT AddRasterConstraints('raster_table'::name, 'column_name'::name);

Hope this helps someone else too with the added details.