Really, that issue with "TILED" geotiffs on overview is a problem of selecting cache size for GDAL. I wish that GDAL_CACHEMAX will be automatically expanded to contain at least one row of unpacked tiles, then the performance issue talked about here will go away.
On Tue, Nov 30, 2021 at 9:44 PM Javier Jimenez Shaw <j...@jimenezshaw.com> wrote: > Yes, that is true. It happened to me once. > What I mean is that the plain vanilla without all defaults (no overviews, > no tiles) is currently manageable. Changing only the "tiled" default would > make the vanilla case unmanageable. And some not expert users will complain. > > Maybe it is good to document that behavior. > > Btw, how spread is the support for tiled TIFFs among other viewers? > > Cheers > > El mar., 30 nov. 2021 19:29, Rahkonen Jukka (MML) < > jukka.rahko...@maanmittauslaitos.fi> escribió: > >> Hi, >> >> >> >> On the other hand those QGIS users pay the price every time when they >> zoom close to the same image because then QGIS must read many super wide >> rows of data instead of just the tiles that intersect the view. Not even >> overviews which are created on top of striped image do not help when user >> hit the native resolution. But perhaps it is not so important what is the >> default, experienced users maybe know what they want. >> >> >> >> -Jukka Rahkonen- >> >> >> >> *Lähettäjä:* Javier Jimenez Shaw <j...@jimenezshaw.com> >> *Lähetetty:* tiistai 30. marraskuuta 2021 11.09 >> *Vastaanottaja:* Rahkonen Jukka (MML) < >> jukka.rahko...@maanmittauslaitos.fi> >> *Kopio:* gdal-dev@lists.osgeo.org >> *Aihe:* Re: [gdal-dev] Should we make also GTiff to use TILED=YES as >> default? >> >> >> >> Hi Jukka >> >> >> >> I don't think it is a good option. >> >> TL;DR: tiled without overviews is extremely slow for a global view. >> >> >> >> If you have a (big) image with TILED=YES but without overviews, it is >> really really slow in QGIS (from seconds to many minutes). >> >> The reason (I guess) is that QGIS is by default sub-sampling the image >> using nearest neighbor. If the image is not tiled, then it has to read only >> every nth line. However, when tiled, at the end has to read the full image >> from file. >> >> The bigger the zoom level, the faster it goes. But waiting 5 minutes to >> see the global view of your image to know where to zoom in... you close >> QGIS and blame somebody. >> >> >> >> That changes dramatically if there are (proper) overviews available, of >> course. >> >> >> >> Cheers >> >> .___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ... .... ._ .__ >> Entre dos pensamientos racionales >> hay infinitos pensamientos irracionales. >> >> >> >> >> >> On Tue, 30 Nov 2021 at 08:04, Rahkonen Jukka (MML) < >> jukka.rahko...@maanmittauslaitos.fi> wrote: >> >> Hi, >> >> >> >> There are loads of questions in the stack.exchange site where users have >> problems with performance when they do something with reading and writing >> very large image files. Big files have obviously become much more common >> now due to clouds. Users try to solve the problem by increasing >> GDAL_CACHEMAX and using multithreading etc. but they use the default >> GeoTIFF settings and keep on writing huge striped TIFFs. I wonder if we >> should make tiling the default also for the GTiff driver like it is in the >> COG driver. >> >> >> >> -Jukka Rahkonen- >> >> _______________________________________________ >> gdal-dev mailing list >> gdal-dev@lists.osgeo.org >> https://lists.osgeo.org/mailman/listinfo/gdal-dev >> >> _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/gdal-dev >
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