<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt">Chaitanya,<br clear="none"><br clear="none">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!<br clear="none"><br clear="none">Attached are two screen shots showing the difference.<br clear="none"><br clear="none">Thanks again!<br clear="none"><br clear="none">Regards,<br clear="none">Ammar<div><span></span></div><div><br></div> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font face="Arial" size="2"> <b><span style="font-weight:bold;">From:</span></b> Chaitanya kumar CH <chaitanya.ch@gmail.com><br> <b><span style="font-weight: bold;">To:</span></b> ammar83_h@yahoo.com <br><b><span style="font-weight: bold;">Cc:</span></b> gdal dev <gdal-dev@lists.osgeo.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, January 21, 2014 6:27 PM<br> <b><span style="font-weight:
bold;">Subject:</span></b> Re: Question about gdaladdo and raster mosaicking<br> </font> </div> <div class="y_msg_container"><br><div id="yiv2661324825"><div dir="ltr">Ammar,</div>
<div dir="ltr">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.</div>
<div dir="ltr">My suggestion is to use another format with lossless compression for the 21 images or use a mask band if you prefer.</div>
<div dir="ltr">Let me know how it goes.</div>
<div dir="ltr">--<br>
Best regards,<br>
Chaitanya Kumar CH</div>
<div class="yiv2661324825gmail_quote">On 21-Jan-2014 5:31 pm, <<a rel="nofollow" ymailto="mailto:ammar83_h@yahoo.com" target="_blank" href="mailto:ammar83_h@yahoo.com">ammar83_h@yahoo.com</a>> wrote:<br><blockquote class="yiv2661324825gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hello Chaitanya,<br>
<br>
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.<br>
<br>
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:<br>
<br>
gdalbuildvrt -srcnodata 255 -vrtnodata 255 -a_srs EPSG:27700 -input_file_list tiff_list.txt mosaic.vrt<br>
<br>
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<br>
<br>
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<br>
<br>
Any ideas, tips or recommendations would be appreciated!<br>
<br>
Best regards,<br>
Ammar<br>
<br>
_____________________________________<br>
Sent from <a rel="nofollow" target="_blank" href="http://osgeo-org.1560.x6.nabble.com/">http://osgeo-org.1560.x6.nabble.com</a><br>
<br>
</blockquote></div></div><br><br></div> </div> </div> </div></body></html>