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<font size=3>Frank,<br><br>
I downloaded and installed FWTools 1.0.0 Win. The gdalwarp
transparency problem did not happen with this new version. I tested
on two images that I would get blue spots on the overlapping areas.
The new version did the transparency without the blue spots. I'll
let you know if it happens with other mosaics.<br><br>
Thanks a lot.<br><br>
Reinaldo.<br><br>
At 03:37 PM 6/5/2006, Frank Warmerdam wrote:<br>
<blockquote type=cite class=cite cite="">Reinaldo Escada Chohfi
wrote:<br>
<blockquote type=cite class=cite cite="">Hello,<br>
I'm runing gdalwarp (FWTools 1.0.0a7) to mosaic geotiff images because
the images are large and I run into memory problems with gdal_merge.<br>
I get some strange results in several mosaics in the overlapping areas
between images. I use -srcnodata 0 to have gdalwarp do the
transparency in these overlapping areas.<br>
My question is, if am using -scrnodata 0, will the transparency be made
when all 3 pixel values are 0, 0, 0 (RGB) or whenever any of the bands
has a pixel value equal to 0? It looks like I get a transparency
only in the Blue, sometimes only in the Red or Green bands and the image
has blue, red or green spots. Do I have to use -scrnodata value
"0 0 0" in order to get transparency only when RGB are equal to
0, 0, 0?<br>
Thanks in advance for the help.</blockquote><br>
Reinaldo,<br><br>
Looking at the code, it seems I implemented UNIFIED_SRC_NODATA as
the<br>
default for gdalwarp circa September 2005. A quick checks shows
FWTools<br>
1.0.0a7 as being built in early November of 2005. So it should
include this.<br><br>
The UNIFIED_SRC_NODATA enabling forces gdalwarp to only consider a pixel
as<br>
nodata if the values match for all bands. So, gdalwarp *should* do
what<br>
you want already. That it is not may be a bug in one or more of
the<br>
warping logic cases.<br><br>
Could you first try a newer FWTools and see if the problem
persists? If it<br>
does, could you submit a bug report detailing how to reproduce your
problem?<br><br>
Best regards,<br>
-- <br>
---------------------------------------+--------------------------------------<br>
I set the clouds in motion - turn up | Frank Warmerdam,
warmerdam@pobox.com<br>
light and sound - activate the windows |
<a href="http://pobox.com/~warmerdam" eudora="autourl">
http://pobox.com/~warmerdam</a><br>
and watch the world go round - Rush | President OSGF,
<a href="http://osgeo.org/" eudora="autourl">http://osgeo.org</a><br>
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