[gdal-dev] Stop gdalladdo eating fillets

[Carlo A. Bertelli (Charta s.r.l.)]

Hallo,
I have a set of very detailed b&w needing an overlay. But when I run
gdaladdo, no matter what option I choose, fillets are spitefully
deleted.
I don't know if there is a better solution, I tried to get a thicker
trace on a copy of the original image, make the pyramids and rename
the resulting file.
To make the fillets grow I used ImageMagick, like this
convert -blur 3 -threshold 20 ORIGINAL.tif THICKER.tif
(the treshold is less than 50 because the original image is white on black)
gdaladdo --config COMPRESS_OVERVIEW DEFLATE -r average  --config
INTERLEAVE_OVERVIEW PIXEL --config NODATA 0 -ro THICKER.tif 2 4 8 16
than I renamed THICKER.tif.ovr as ORIGINAL.tif.ovr.
Well, it doesn't work well, I should have made a thicker version while
I was reducing the image. There is always a size where fillets
disappear.
The problem seems to ask for a resize method that keeps the thickness
of the lines while reducing the objects. There should be a procedure
like mine but carefully adapted to any scale reduction.
Am I missing something or this is really a problem?
Carlo
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