[gdal-dev] Problem fixing the Starting point of a tiling job

[M. LATTES]

Hi Moses, 

 

when starting coordinate is shifted, is it a large shift ?

Are you using gdalwarp command only for tiling or did you change SRS
(-t_srs) too ?

 


Regards.

 

Mathieu LATTES

 <http://www.interatlas.fr/> http://www.interatlas.fr
 <http://www.urbimap.com/> http://www.ubick.net

 

 

De : gdal-dev-bounces at lists.osgeo.org
[mailto:gdal-dev-bounces at lists.osgeo.org] De la part de
Moses.Gone at t-systems.com
Envoyé : mercredi 12 mars 2014 11:22
À : gdal-dev at lists.osgeo.org
Objet : [gdal-dev] Problem fixing the Starting point of a tiling job

 

Dear Experts,

 

When tiling datasets, we want to specifically define custom windows. To do
this, we are using -te option during warping. The warped output is then
tiled. 

 

The problem though is that after tiling and checking the bbox of the first
tile, we have noticed that the starting coordinate is shifted and do not
correspond to the defined starting coordinates as illustrated below:

 



*	The blue grid represent the original dataset with cellsize (a).
*	The black grid represent the new dataset with cellsize (b).
*	The cellsize of both datasets can be the same or not [(a) .eq. (b)
or (a) .ne. (b)].
*	The red polygon represent the bbox which fit to the new cellsize and
tilesize.

 

We would like to start tiling exactly at the upper left corner of the red
polygon.How we can force gdal to clip the raster exactly according to our
well defined bbox?

 

In some cases, GDAL picks the right Bbox startpoint, in other cases it
doesnt. Is this somehow related to the difference in the input and output
data resolution(cellsize)?

 

We can’t figure out why it is ignoring our definitions. Could someone help
shade some light to what is happening here?

 

Thanks in advance,

Moses

 



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