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 tileindex. > > > > 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 http://www.gdal.org/gdal_vrttut.html#gdal_vrttut_overviews. 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 http://latuviitta.org/documents/GDAL_Scale_dependent_VRT_test.zip 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. -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
