[postgis-users] FW: Postgis raster data display

[Mauricio de Paulo]

Hi Pierre and Celati,
First, I should explain that the GDAL driver may have a reported bug 
when trying to read overviews. You may experience performance issues on 
GDAL 1.9.
I've reported the bug and it should be fixed on  GDAL 1.9.1
http://trac.osgeo.org/gdal/ticket/4649


1/What do you think about overviews values ?
Usually, overviews are assigned dividing the image size by 2. I really 
don't know what to expect with custom overviews. GDAL cannot read it at 
the moment.

2/According to you, the plugin is abble to display a sql file with a 
size of 679 MO ?
It may display with a huge delay. When GDAL's bug is fixed it should be 
no problem at all.

3/In native, these data have 5 bands but we need display only 3 bands. 
According to you, is it better before importing these data in database 
to remove 2 useless bands in order to speed up the display ?
That's probably helpfull. I don't really know about how much it's going 
to improve, but if you can avoid 66% table size increase, why not?

4/Is there update regarding the speed problem ( Gdal driver issue).
 From the link above I assume that it's under development.

5/Is there another way faster (Gvsig for instance) in displaying postgis 
raster data?
I'm not really following GvSIG's development. If they use the same 
driver it's most likely that they are running into the same bug.


All the Best,
Mauricio de Paulo

On 07/10/2012 12:24 PM, Pierre Racine wrote:
> Mauricio,
>
> We receive many questions regarding the QGIS plugin in the PostGIS user list. Would you prefer us to tell them to ask their question in the QGIS list (now GIS Stack Exchange) or would you we willing to follow postgis-users and answer them when appropriate?
>
> I never use the plugin myself so I am of no help.
>
> Pierre
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of celati laurent
> Sent: Tuesday, July 10, 2012 7:03 AM
> To: postgis-users at postgis.refractions.net
> Subject: [postgis-users] Postgis raster data display
>
> Hello,
>
> I'm trying to display "Raster postgis data" via Qgis ("Load Postgis
> Raster Layer"). It works but it's a bit slow!
> These raster are 11 Rapideye satellite images with 5 bands in native. I
> defined following overviews for each data : 3,9,27,81,243
> Size of smallest SQL file : 270 MO
> Size of biggest SQL file : 679 MO
>
> 1/What do you think about overviews values ?
> 2/According to you, the plugin is abble to display a sql file with a
> size of 679 MO ?
> 3/In native, these data have 5 bands but we need display only 3 bands.
> According to you, is it better before importing these data in database
> to remove 2 useless bands in order to speed up the display ?
> 4/Is there update regarding the speed problem ( Gdal driver issue).
> 5/Is there another way faster (Gvsig for instance) in displaying postgis
> raster data?
> Thank you to throw light for me.
>
> Regards.
>
> Laurent Celati.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20120710/9296cd0e/attachment.html>