Ralf,<br><br>Try the -addalpha and -srcnodata options in gdalbuildvrt (<a href="http://www.gdal.org/gdalbuildvrt.html">http://www.gdal.org/gdalbuildvrt.html</a>) to generate a VRT file to represent your files, individually or combined. Mention the RGB values of the white pixels as -srcnodata values. This will add an alpha band to your images and makes all white pixels transparent.<br>
<br>Run gdal_retile.py using the vrt files.<br><br><div class="gmail_quote">2010/2/4 Ralf Wagner <span dir="ltr"><<a href="mailto:rpw@globema.pl">rpw@globema.pl</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hello,<br>
I am creating image pyramid from a bunch of color GeoTIFF files using<br>
"gdal_retile" tool. I have managed to generate pyramid but unfortunately<br>
there is a problem - my GeoTIFFs maps overlap and have white margins<br>
around and I am unable to force GDAL to treat white color as transparent<br>
to avoid covering maps by these margins. I have tried all ideas I could<br>
imagine but to no avail. So my question is: how to tweak "gdal_retile"<br>
to get white color treated as transparent during merging?<br>
I am using GDAL 1.6 on Windows. Any help will be very, very appreciated<br>
- thank you.<br>
<br>
-- <br>
Ralf Wagner<br>
<br>
<br>
<br>
_______________________________________________<br>
gdal-dev mailing list<br>
<a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br>
<a href="http://lists.osgeo.org/mailman/listinfo/gdal-dev" target="_blank">http://lists.osgeo.org/mailman/listinfo/gdal-dev</a><br>
</blockquote></div><br><br clear="all"><br>-- <br>Best regards,<br>Chaitanya kumar CH.<br>/tʃaɪθənjə/ /kʊmɑr/ <br>+91-9848167848<br>17.241582N 80.142635E<br>