[Gdal-dev] optimum overview settings?

[Frank Warmerdam]

Xiaodong Zhang wrote:
> Hi Frank,
> 
> Hope you don't mind my jumping into this discussion. Just want to double check
> with you. I run overview at 2 4 8 16 for all the images using crontab. I noticed
> the crontab did not run for a period of time and I don't know which images have
> or not have overview. So I just run the overview again to all the images with
> the same overview scheme 2 4 8 16. Will this create a duplicate overview of 2 4
> 8 16 2 4 8 16 as suggested by Martin, or as you have indicated it will simply
> replace the existing matching overview layer.

Zhang,

It should be fine to run gdaladdo on all the files, and it should just overwrite
existing overviews if they are there.  It worked for me.  But it is possible
that in older versions of GDAL or for some particular arrangements it will
be broken.  I would suggest experimenting.

Note that gdalinfo will report the overviews that existing down in the
per-band area.

Best regards,
-- 
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