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<DIV><FONT face=Arial size=2>Hi all !</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Once again, I'm here !!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So my results :</FONT></DIV>
<DIV><FONT face=Arial size=2>- tps has no effects at all,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>- generating a merge with gdalwarp on a small
number of files </FONT></DIV>
<DIV><FONT face=Arial size=2> or</FONT></DIV>
<DIV><FONT face=Arial size=2>generating a merge with gdalwarp on all the files
plus specifying the same extent of the small number of files</FONT></DIV>
<DIV><FONT face=Arial size=2>does not give me the same result.</FONT></DIV>
<DIV><FONT face=Arial size=2>In the first case, the image is great with no
artefacts, in the second case the image is not good at all with duplicated
groups of pixels along vertical and horizontal lines. One could see the results
on the same files as previously : <A
href="http://benoit.andrieu.free.fr/mapserver/Clipboard02.png">http://benoit.andrieu.free.fr/mapserver/Clipboard02.png</A></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Has anyone any tips for me ?? ^^</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Benoît</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bea@ixsea.com href="mailto:bea@ixsea.com">Benoît Andrieu</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mapserver-users@lists.osgeo.org
href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 23, 2008 10:33
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [mapserver-users]
Reprojection image quality</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>
<DT>Hi all !</DT></DIV>
<DIV> </DIV>
<DIV>I am trying to play with the parameters of gdalwarp.</DIV>
<DIV> </DIV>
<DIV>It seems that the tps option gives better output result than omitting
this parameter.</DIV>
<DIV>I just tried on a subset of my data and the resulting picture is very
nice comparing to the previous. Right now, I am trying it on the whole
dataset.</DIV>
<DIV> </DIV>
<DIV>By the way, could someone explain what it really does ? </DIV>
<DIV>Is this a better/different algorithm ?</DIV>
<DIV> </DIV>
<DIV>
<DT>-tps:
<DD>Force use of thin plate spline transformer based on available GCPs.
</FONT></DD></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Benoît</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bea@ixsea.com href="mailto:bea@ixsea.com">Benoît Andrieu</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mapserver-users@lists.osgeo.org
href="mailto:mapserver-users@lists.osgeo.org">mapserver-users@lists.osgeo.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 23, 2008 9:24
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [mapserver-users] Reprojection
image quality</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>
<DIV>
<DIV><FONT face=Arial size=2>Hello guys !</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I currently have some problems in the quality
of the images produced by GDAL/Mapserver.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>We are using MapServer to serve raster imagery
to NASA Worldwind.</FONT></DIV>
<DIV><FONT face=Arial size=2>Our files are in UTM and Worldwind needs WGS84
images so we do reprojection on the fly.</FONT></DIV>
<DIV><FONT face=Arial size=2>Using this, we can clearly see image quality
artefacts between Worldwind (using WGS84, no choice) and a custom internal
tool (showing original data).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I can reproduce the problem using gdalwarp tool
using a very simple command line :</FONT></DIV>
<DIV><FONT face=Arial size=2>gdalwarp -multi -t_srs EPSG:4326 -srcnodata 0
-dstnodata 0 -r near %FileSrc%/*_p_*8bit.tif %FileDest%</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You can see the result on <A
href="http://benoit.andrieu.free.fr/mapserver/Clipboard02.png">http://benoit.andrieu.free.fr/mapserver/Clipboard02.png</A> :
on the right, the original image and on the left, the resulting
output.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>I suspect that using some others settings,
I could improve the quality on gdalwarp's output in a first time and on
mapserver's output in a second time but I don't know where to
start...</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So if anyone could help or suggest anything, he
will be welcome !!!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks in advance,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Benoît</FONT></DIV></DIV></FONT></DIV>
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