As was suggested, you could try using a mask instead.
On Thu, Jan 23, 2014 at 7:52 AM, Ammar <[email protected]> wrote: > Chaitanya, > > Thank you very much for your reply and suggestion. I have used LZW with > predictor 2 compression and added external overviews compressed in LZW too > and the image came perfect. The only downside is the size of each of the > images has expanded from approx. 2 GB to 18-20 GB. So now I have to choose > between quality and size! > > Attached are two screen shots showing the difference. > > Thanks again! > > Regards, > Ammar > > ------------------------------ > *From:* Chaitanya kumar CH <[email protected]> > *To:* [email protected] > *Cc:* gdal dev <[email protected]> > *Sent:* Tuesday, January 21, 2014 6:27 PM > *Subject:* Re: Question about gdaladdo and raster mosaicking > > Ammar, > You are using lossy JPEG compression. I'm guessing that the white lines > are are actually pixels with values near but not equal to 255. So, they are > not treated as nodata pixels. > My suggestion is to use another format with lossless compression for the > 21 images or use a mask band if you prefer. > Let me know how it goes. > -- > Best regards, > Chaitanya Kumar CH > On 21-Jan-2014 5:31 pm, <[email protected]> wrote: > > Hello Chaitanya, > > I was looking online for solutions to my problem and I cam across some of > your posts so I thought you might help me with my problem. > > I have 10,000+ TIFF files that I want to merge into one big Image and > serve using GeoServer. I merged every 500 images at a time creating using > gdalbuildvrt and gdal_translate along with JPEG compression creating 21 > TIFF files. I added overviews then to each of the new 21 files. When adding > the images together, once directly as files using QGIS and another time as > WMSs using GeoServer, I got white lines/gaps precisely at the border of > ever 2 images. I thought the problem is with no data values but I decided > to take another approach and merged all the 10,000 files into one huge > image and this time I got one perfect image with no lines or gaps. I failed > to create overviews for the big image because the process took days or > gdaladdo running with no progress. I tested then on smaller images with and > without overviews and the ones with no overview came perfect while the one > with gdaladdo overviews came with the same problem of lines and gaps. The > commands I m using are the following: > > gdalbuildvrt -srcnodata 255 -vrtnodata 255 -a_srs EPSG:27700 > -input_file_list tiff_list.txt mosaic.vrt > > gdal_translate -of GTiff -co TILED=YES -co BIGTIFF=YES -co COMPRESS=JPEG > -co JPEG_QUALITY=80 -co BLOCKXSIZE=512 -co BLOCKYSIZE=512 -co > PHOTOMETRIC=YCBCR mosaic.vrt mosaic.tif > > gdaladdo mosaic.tif -r average --config COMPRESS_OVERVIEW JPEG --config > JPEG_QUALITY_OVERVIEW 60 --config INTERLEAVE_OVERVIEW PIXEL --config > PHOTOMETRIC_OVERVIEW YCBCR 2 4 8 16 32 64 128 256 512 > > Any ideas, tips or recommendations would be appreciated! > > Best regards, > Ammar > > _____________________________________ > Sent from http://osgeo-org.1560.x6.nabble.com > > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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