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<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:</DT>
<DD>Force use of thin plate spline transformer based on available GCPs.
</DD></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 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>
<P>
<HR>
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