On mardi 21 avril 2020 23:54:03 CEST Denis Rykov wrote: > Hello, > > I'm using *.vrt file that is built atop of COG rasters with internal mask > (PER_DATASET) + external overview file *.vrt.ovr. > These files are stored on Azure Blob Storage and I get access to them using > /vsiaz scheme. > I've found out that when I read data from this VRT GDAL does few requests > to *.vrt.ovr to get data and lots of requests to TIFFs to extract a mask. > > What are the ways to overcome this? I hope I can put mask into > sidecar *.vrt.msk file. Is that correct? > Is there a way to store a mask inside a *.vrt.ovr file?
Hum, given a rgbmask.vrt that has a mask band, the following probably works gdal_translate rgbmask.vrt rgb_with_external_msk.vrt -b 1 -b 2 -b 3 -of VRT gdal_translate rgbmask.vrt rgb_with_external_msk.vrt.msk -b mask -of VRT -mo INTERNAL_MASK_FLAGS_1=2 -mo INTERNAL_MASK_FLAGS_2=2 -mo INTERNAL_MASK_FLAGS_3=2 gdaladdo rgb_with_external_msk.vrt.msk You could probably avoid rgb_with_external_msk.vrt referencing rgbmask.vrt, by making it directly refer to your COG sources. Even -- Spatialys - Geospatial professional services http://www.spatialys.com
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