[gdal-dev] Should we make also GTiff to use TILED=YES as default?

[Darafei "Komяpa" Praliaskouski]

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 <j1 at 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.rahkonen at 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 <j1 at jimenezshaw.com>
>> *Lähetetty:* tiistai 30. marraskuuta 2021 11.09
>> *Vastaanottaja:* Rahkonen Jukka (MML) <
>> jukka.rahkonen at maanmittauslaitos.fi>
>> *Kopio:* gdal-dev at 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.rahkonen at 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-
>>
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