[gdal-dev] gdaladdo very slow

[Pietro Rossin]

Hello
I must mosaic and compress many 1 bit images that should be used mainly by
qgis users and ArcGIS users.
After many attempts I have mosaicked them (983 images/998Mb) by this
procedure

1) make a vrt mosaic
gdalbuildvrt -hidenodata -srcnodata “0” -vrtnodata "0" test.vrt *.tif

2) make a geotiff (result 1060Mb)
gdal_translate -of Gtiff -co SPARSE_OK=TRUE -a_nodata 0 -co NBITS=1 -co
"TILED=YES" -co "COMPRESS=CCITTFAX4" -co "INTERLEAVE=BAND" -co "TFW=YES"
"test.vrt" "test.tif"

3) add overview
I tried many ways..
a) with external pyramids: gdaladdo -r nearest --config COMPRESS_OVERVIEW
deflate  --config USE_RRD YES immagine.tif 4 8 16 32 64 128 256
It works, a big file aux (1.6Gb) is created, qgis can recognize pyramids but
ArcGIS does not. Processing time less than 2 hours
b) with external pyramids using RRD:
gdaladdo -r nearest --config COMPRESS_OVERVIEW deflate --config HFA_USE_RRD
YES --config USE_RRD YES immagine.tif 4 8 16 32 64 128 256
It works, a small file aux (16Kb) is created and a big rrd file (1.6Gb) is
created too, qgis can recognize pyramids but ArcGIS does not. Processing
time less than 2 hours.
c) using internal pyramids
gdaladdo -r nearest --config COMPRESS_OVERVIEW deflate immagine.tif 2 4 8 16
32 64 128 256
With this option gdaladdo start working but right now it hasn't finished (I
added 1 level); imagine.tif is growing to 2.3Gb and the process is at 60%
after 3 days....
In task manager gdaladdo uses less than 10%CPU all the time...

My computer is old but rather powerful (dual opteron 4Gb ram).

What could it be that gdaladdo is so slow?
And
which is the best way to compress these images so they can e used both in
qgis and arcgis?

Thanks for your patience
Pietro



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