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

[Bborie Park]

You could post-process those tiles on the east and south by running them
through ST_Clip.  Since the pixels that are NODATA are consistently
located, the geometry to clip upon shouldn't be hard to make.

And correct to your last sentence.  If you're using released versions of
GDAL and clip the east and south tile, GDAL will fail as this violates
the rules of regular blocking.

-bborie

On 08/27/2012 07:51 AM, Jakub Hettler wrote:
> 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
>>>
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
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>>>
>>
>>
>>
>> --
>> Bborie Park
>> Programmer
>> Center for Vectorborne Diseases
>> UC Davis
>> 530-752-8380
>> bkpark at ucdavis.edu
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
> 
> 
> 
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-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu