[postgis-users] irregular tiling with raster2pgsql - imported raster has nodata value on the edge

[Pierre Racine]

This is ticket #826

http://trac.osgeo.org/postgis/ticket/826

Pierre

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> bounces at postgis.refractions.net] On Behalf Of Jakub Hettler
> Sent: Monday, August 27, 2012 10:51 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] irregular tiling with raster2pgsql - imported raster
> has nodata value on the edge
> 
> Hi Bborie,
> I think, that not all rasters are divisible without remainder (except 1x1 tile) :)
> 
> My problem is this (this is my raster after raster2psql displayed with tiles)
> 
> http://sdrv.ms/OjbhoD
> 
> I need to cut the last tiles on the east and south a make it smaller by the red line
> 
> But I think it is impossible now, but i will find the solution :)
> 
> I think about the function which will find the line of nodata value and then I
> make the polygon and intersect it with this polygon. :D
> 
> But if I understand it, if I cut last tiles and these will be smaller than others, I
> wont be able to load this raster into QGIS (PostGIS raster driver)
> 
> Thanks
> 
> Jakub
> 
> 
> 
> 
> 
> 
> 2012/8/26 Bborie Park <bkpark at ucdavis.edu>
> 
> 
> 	Currently, that behavior is as expected due to the application of the
> 	specified tile size from the upper-left corner.  To minimize the tiles
> 	with large swaths of NODATA, you should try to use a tile size that is
> 	cleanly divisible (no remainder) by the raster's width and height or a
> 	size with a large remainder.  I usually recommend tile sizes of
> 	100x100 or smaller though sizes around 50x50 are even faster.  In
> 	terms of performance, the smaller the time size, the better the
> 	performance.
> 
> 	-bborie
> 
> 
> 	On Sun, Aug 26, 2012 at 10:22 AM, Jakub Hettler
> <jakub.hettler at gmail.com> wrote:
> 	> Hi all,
> 	> I would like to ask if there is a way how to import tiled raster into
> 	> PostGIS through raster2pgsql, but I need to make tiled raster, say
> 256x256,
> 	> but at the end of raster I have last tiles (on the east and south side)
> 	> which is on half out of the original raster (raster ends fe in the middle
> of
> 	> last tile). If I try to load imported raster into QGIS or use
> gdal_translate
> 	> I have nodata value on this place in the raster. Is there a way how to
> 	> import the raster with the smaller last tiles on the east and south
> edges?
> 	>
> 	> Thanks
> 	>
> 	> Jakub
> 	>
> 
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> 
> 
> 
> 	--
> 	Bborie Park
> 	Programmer
> 	Center for Vectorborne Diseases
> 	UC Davis
> 	530-752-8380
> 	bkpark at ucdavis.edu
> 
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