Osahon,

 

It depends what you are trying to show and do.

 

1)      For example if you create overviews on your out-db, those will show, so 
then it would only be when you zoom in that you hit the out-db that you'd get 
black.

 

2)      If you are looking to inspect a slice of out-db with QGIS, you can 
create a view that has just the piece you want to show and drag it to your map.

You'd need to apply a function that forces that piece into in-db.  Not all 
raster functions do that and sadly we haven't been good about documenting ones 
that do vs. ones that don't.

 

I know for sure that ST_Resize would force a materialized in-db and that might 
actually be a good one to use anyway since it would lower the res allowing you 
to see more.

 

 

So something like

-- do this with db manager or pgAdmin

 

CREATE OR REPLACE VIEW vw_outdb_sample AS

SELECT rid, ST_Resize(rast,0.8, 0.8) AS rast

FROM some_outdb_table

WHERE ST_Intersects(rast,some_geometry);

 

 

Then drag this view to your Map.

 

 

Hope that helps,

Regina

 

 

From: Osahon Oduware [mailto:[email protected]] 
Sent: Friday, April 28, 2017 10:13 AM
To: PostGIS Users Discussion <[email protected]>
Cc: Regina Obe <[email protected]>; [email protected]
Subject: GDAL OUT-DB RASTER SUPPORT

 

Hi All,

I am getting a black image when I try to display PostGIS out-db rasters. I 
discovered that it has to do with GDAL support for out-db rasters as stated in 
the link below for a similar issue (over 1 year back):
https://hub.qgis.org/issues/12133

The last comment by Jürgen Fischer states "... only black images. So it's a 
dependency issue (GDAL complains ERROR 1: This raster has outdb storage. This 
feature isn't still available)."

I have also been told in the link below that "out-db support is not implemented 
yet in the GDAL PostGISRaster driver.":
https://lists.osgeo.org/pipermail/gdal-dev/2017-April/046512.html

I would like to know how to solve this issue of displaying postgis out-db 
rasters in QGIS?

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