[gdal-dev] Spatial index to raster VRT
jukka.rahkonen at maanmittauslaitos.fi
Thu May 26 06:26:38 PDT 2016
Daniel Morissette <dmorissette <at> mapgears.com> writes:
> On 2016-05-26 8:40 AM, Jukka Rahkonen wrote:
> > Hi,
> > Any thoughts about alternatives to implement the feature request from
> > https://trac.osgeo.org/gdal/ticket/5762?
> > What I dream of is to be able to utilize all the nice on-the-fly tweaks that
> > can be done with VRT at similar speed that Mapserver is reaching with
> That would be a nice enhancement. As usual I guess we need a champion
> and/or some funding to make this happen.
> I came across a similar use case not long ago and realized that to get
> top performance at all zoom levels we'd also need the ability to
> associate overviews with the VRT. I didn't check if creating external
> overviews with gdaladdo would work for a VRT already. Maybe it does?
It does and is even documented in
VRT supports one overview, but that can itself be a VRT, which in turn can
point to next VRT overview and so on. Easier than to explain is to give a
link to this old experiment
Unzip and open the best resolution VRT t0320.vrt with QGIS, zoom in, and you
should see how 5 different tiff files with different pixel size and
rendering styles behave.
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