Pierre, the issue must be "-srcnodata b4". You probably intended b4 to be understood as band 4, but the value expected is a numeric value so b4 is actually understood as 0. I've just added validation of those arguments, so that this doesn't get unnoticed.
You should just remove "-srcnodata b4" and try again. On a very simple artificial example, I get the expected result. Note however than gdalbuildvrt has no particular handling for alpha bands, If you have 2 rasters that overlap partially, it will not do any blending. i.e. a transparent area of the raster listed in last position in the gdalbuildvrt command line will completely override the raster beneath. You need gdalwarp for better handling of transparency. Even > Hi list, > > Im trying to assembly some RGBA tiff in one with gdalbuildvrt and then to > translate them to a RGB TIFF tiled file YCBCR jpeg compressed. > > No problem But now, I would like to get a white color in the background > instead of the black. > > > > The following commands work but I get nodata (and so, black) on any white > pixels whereas I just wanted to convert alpha to white The problem in on > the vrt. > > > > gdalbuildvrt assembly.vrt -srcnodata b4 hidenodata -vrtnodata 255 *.tif > > gdal_translate -of GTIFF -b 1 -b 2 -b 3 -co COMPRESS=JPEG -co > JPEG_QUALITY=95 -co TFW=YES -co BIGTIFF=YES -co ALPHA=NO -co TILED=YES -co > PHOTOMETRIC=YCBCR -co PROFILE=BASELINE assembly.vrt assembly_JPG.tif > > gdaladdo -r gauss -ro --config COMPRESS_OVERVIEW JPEG --config > JPEG_QUALITY_OVERVIEW 95 --config BIGTIFF_OVERVIEW YES --config > PHOTOMETRIC_OVERVIEW YCBCR --config INTERLEAVE_OVERVIEW PIXEL --config > NODATA_VALUES 255 assembly_JPG.tif 2 4 8 16 32 64 128 256 > > > > Do you have an idea? The problem is the is not init option, just > -vrtnodata 255 255 255 to fix both background color but also the nodata > bandper band > > > > Pierre CARREAUD > > Spécialiste en imagerie numérique > > > > > carte_voeux_2014 > > LINGÉNIERIE DE LA DURABILITÉ > > > > SITES Entité Île-de-France > > Division du Développement Technique > > 2 bis avenue du Centre > > 92500 Rueil-Malmaison, France > > Tel : 01 41 39 02 00 / Fax : 01 41 39 02 01 > > <http://www.sites.fr/> www.sites.fr > > > > CARRES EXPERTISE cid:image002.jpg@01CB7A74.CDE1E680 INSTRUMENTATION / > MESURES cid:image002.jpg@01CB7A74.CDE1E680 INGENIERIE -- Geospatial professional services http://even.rouault.free.fr/services.html _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev