[gdal-dev] Request for clarification on SPARSE_OK=TRUE and empty tiles relation

Daniele Romagnoli daniele.romagnoli at geo-solutions.it
Mon May 16 05:56:12 PDT 2016

Hi list,
I have seen a recent email on that list about filling empty tiles and
SPARSE_OK creation option (titled "Geotiff FillEmptyTiles with no data
I would like to understand a little better how it works.

Suppose I have 2 isolated GeoTiff files of the same datatype, let's say one
covering California and the other covering France.
I do a gdalbuildvrt to mosaic them together and then I convert the VRT to
At which level the SPARSE_OK flag and void blocks management are taken into
I was "hoping" that using the SPARSE_OK=TRUE create option when translating
VRT to GeoTiff would have resulted into having an output smaller with
respect to an output generated without that creation option since there is
a wide void area in the middle.
Why I get the same size in both cases? Shouldn't it avoid filling void
blocks in the gap?
Is the VRT Driver iterating on all the tiles involved in the final bounding
box so that it forces a write of each block even if there is no source
dataset for that tile?

Please, let me know.
Best Regards,

GeoServer Professional Services from the experts! Visit
http://goo.gl/it488V for more information.

Ing. Daniele Romagnoli
Senior Software Engineer

GeoSolutions S.A.S.
Via di Montramito 3/A
55054  Massarosa (LU)
phone: +39 0584 962313
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