[gdal-dev] overview sizes for COG

[Michael Sumner]

Hi, can we specify overview sizes exactly? I have this odd grid that is
36000x17999, and I get consequently yucky overview sizes:

gdal_create -outsize 36000 17999 -ot Int8 -co SPARSE_OK=YES -a_srs
EPSG:4326 -a_ullr 0 17999 0 36000 weird.tif
gdal_translate weird.tif cog.tif  -of COG
gdalinfo cog.tif | grep Overviews
#  Overviews: 18000x8999, 9000x4499, 4500x2249, 2250x1124, 1125x562,
562x281, 281x14

Should I worry about this?  Can the sizes be specified via Translate? (I
can see how they could be generated externally and bundled, but I'm looking
for a way at this high level).

( Maybe I shouldn't even care about the sizes ... and maybe I should
resample the grid to be a better overall size, but I consider that out of
scope here.)

I'm comparing with other COG creators, e.g. odc which makes tidy overviews
( I will explore how it's getting done).

import xarray
from odc.geo.xr import assign_crs
from odc.geo.cog import write_cog

ds = xarray.open_dataset("weird.tif")
ds = assign_crs(ds, crs="EPSG:4326")  ## do something to tag it as odc


write_cog(ds["band_data"], "odc.tif")
os.system("gdalinfo odc.tif | grep Overviews")
#  Overviews: 18000x9000, 9000x4500, 4500x2250, 2250x1125, 1125x563

Cheers, Mike


-- 
Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20240320/5797667e/attachment.htm>