Il 08/08/2016 16:26, Ari Jolma ha scritto:
08.08.2016, 16:42, Margherita Di Leo kirjoitti:
Ari,
On Mon, Aug 8, 2016 at 3:01 PM, Ari Jolma wrote:
08.08.2016, 15:19, Margherita Di Leo kirjoitti:
Dear all,
is there a simple way to create tiles with a certain overlap?
Do you mean by "overlap" the geographic area the tiles should
cover? gdal2tiles.py creates the tiles for the area the source
dataset covers. So you can control the area through the source
dataset.
Thanks for your answer, sorry I'm not sure I understand the
methodology you are proposing. Let me explain what I'm trying to do so
that the problem is clearer. I have a dataset that is a global
coverage, e.g. GMTED [1]. That is a tiled dataset. However for my
processing chain I need tiles that overlap on each other for a certain
number of pixels. This means that the area at the border of each tile
should be covered by the tile itself and by the adjacent one to
certain extent.
Ok. I've done similar thing when I needed to get overlapping tiles to
produce shaded relief tiles on the fly from a DEM. My processing chain was:
1) define the wanted tile (rectangle)
2) expand it by some amount
3) grab the expanded tile from the source (GDAL Translate)
4) process the expanded tile (in my case DEMProcessing)
5) shrink the wanted tile
6) grab the original wanted tile from the result of the processing (GDAL
Translate again)
7) deliver the final product
(BTW, I'll present this in my FOSS4G 2016 talk)
As the first thought I'd do the same access the source dataset with GDAL
and grab the data as such rectangles as you need (not the native tiles
on the server) - i.e., your overlapping tiles.
My method would be the following. I would create a virtual mosaic and
then create the tiles with this rule. From the manual of
gdal2tiles.py it is not clear to me if i can obtain this result. What
do you mean by "you can control the area through the source dataset"?
I mean simply set the area of the source but it is not relevant here
since your problem is different.
I think you need to write your own code as gdal2tiles is probably not
the solution.
Hi all,
if we have calculated the tileindex with overlaps yet, a simple
approach could consist into restricting the desired cutline features
based on attribute query using gdalwarp. For instance:
gdalwarp -co COMPRESS=DEFLATE -co TILED=YES -cutline basilicata.shp
-crop_to_cutline -overwrite -cwhere NOME_COM='Potenza' -dstnodata
-99999.0 eu_dem_bas.vrt eu_dem_Potenza.tif
where, instead of NOME_COM you can use the tilename or simply an
incremental index. Writing a loop over the index should be the easy
part of the task. ;-) Hope this helps!
ciao
Antonio
--
Antonio Falciano
http://www.linkedin.com/in/antoniofalciano
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