[postgis-devel] [PostGIS] #498: Gdal export of some files gives blank image

[PostGIS]

#498: Gdal export of some files gives blank image
-----------------------+----------------------------------------------------
 Reporter:  robe       |       Owner:  pracine        
     Type:  defect     |      Status:  new            
 Priority:  medium     |   Milestone:  WKTRaster 0.1.6
Component:  wktraster  |     Version:  trunk          
 Keywords:             |  
-----------------------+----------------------------------------------------
 I think my mapserver problems may be related to my export issues, and I'm
 not quite sure where the problem lies.

 I tried this example from
 http://trac.osgeo.org/gdal/wiki/frmts_wtkraster.html
 {{{
 C:\python25\python gdal2wktraster.py -r small_world.tif -t
 ch13.small_world -l 1 -k 40x20 -o small_world.sql -s 4326
 }}}

 Then tried to export it with

 {{{
 gdal_translate -of PNG PG:"host=localhost dbname=
 'wktraster_postgis15' user='postgres' password='whatever' schema='ch13'
 table=sm
 all_world" C:\small_world.png

 gdal_translate -of JPEG -band 1 PG:"host=localhost dbname=
 'wktraster_postgis15' user='postgres' password='whatever' schema='ch13'
 table=sm
 all_world" C:\small_world_bw.jpg
 }}}

 And those both work fine, but if I try to do the same thing with the
 PostGIS elepant, I just get a blank or black screen output.


 {{{
 C:\python25\python gdal2wktraster.py -r pele.png -t ch13.pele2 -l 1 -k
 40x20 -o pele2.sql
 psql -h localhost -d wktraster_postgis15 -U postgres -f pele2.sql

 gdal_translate -of PNG PG:"host=localhost dbname=
 'wktraster_postgis15' user='postgres' password='whatever' schema='ch13'
 table=pele2" C:\pelefromdb.png
 }}}

 Just gives me a black box or blank image of the right dimensions.

 I had the same issue with a georefenced MrSID file I had converted to
 georeferenced JPEG and then loaded in, but I thought maybe it was my
 conversion statement.

 I tried on an ArcView Raster file (BIL) and exported that and that seemed
 to work fine.

 So now I'm beginning to thinks its either the pixel types or original file
 type.  Quick scan of pixel values in db look right to me well they are
 definitely all differnt numbers.

 Attached is the PostGIS elephant to test with.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/498>
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