[postgis-devel] [PostGIS] #895: [raster]: FV.01 functions

PostGIS trac at osgeo.org
Fri Apr 1 07:45:56 PDT 2011

#895: [raster]: FV.01 functions
 Reporter:  dustymugs       |       Owner:  pracine              
     Type:  patch           |      Status:  new                  
 Priority:  medium          |   Milestone:  PostGIS Raster Future
Component:  postgis raster  |     Version:  trunk                
 Keywords:                  |  

Comment(by dustymugs):

 Replying to [comment:3 pracine]:
 > Some questions:
 > -Would it not be more useful to provide PostGIS users with flexible but
 more user friendly parameters for Tiff, JPEG, and PNG so that we don't
 have to copy or refer to the GDAL doc? It would be our job to wrap those
 to the option strings provided to _st_asgdalraster(). We could provide
 both the wrapped ones and the generic ones (in case our wrapped one are
 not yet aligned to GDAL or we do not provide a very specific option).

 Yes, you are correct.  I plan on writing the appropriate ST_AsPNG,
 ST_AsJPEG and ST_AsTIFF variations today and over the weekend.  Most of
 the ones I've written thus far are generic and meant to provide a raw

 > -How will 1, 2, 4 or more band rasters be converted to JPEG and/or PNG?

 I know that 1 and 3 band rasters work fine.  I'm thinking of raising a
 notice for rasters with 2, 4 or more bands and only using the first band.

 > -What is the use of the "srs text" parameter?

 I couldn't find a way to get the srtext (or proj4text if srtext isn't
 available) in rt_pg.c for a raster's srid to embed as the GDAL raster's
 srs.  GeoTIFF does support this while PNG and JPEG do not.  If there is a
 correct way to get the srtext from rt_pg.c, please let me know.

Ticket URL: <http://trac.osgeo.org/postgis/ticket/895#comment:4>
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