Hi all !

I am trying to play with the parameters of gdalwarp.

It seems that the tps option gives better output result than omitting this 
parameter.
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.

By the way, could someone explain what it really does ? 
Is this a better/different algorithm ?

-tps:
Force use of thin plate spline transformer based on available GCPs. 

Benoît

  ----- Original Message ----- 
  From: Benoît Andrieu 
  To: mapserver-users@lists.osgeo.org 
  Sent: Tuesday, September 23, 2008 9:24 AM
  Subject: [mapserver-users] Reprojection image quality


  Hello guys !

  I currently have some problems in the quality of the images produced by 
GDAL/Mapserver.

  We are using MapServer to serve raster imagery to NASA Worldwind.
  Our files are in UTM and Worldwind needs WGS84 images so we do reprojection 
on the fly.
  Using this, we can clearly see image quality artefacts between Worldwind 
(using WGS84, no choice) and a custom internal tool (showing original data).

  I can reproduce the problem using gdalwarp tool using a very simple command 
line :
  gdalwarp -multi -t_srs EPSG:4326 -srcnodata 0 -dstnodata 0 -r near 
%FileSrc%/*_p_*8bit.tif %FileDest%

  You can see the result on 
http://benoit.andrieu.free.fr/mapserver/Clipboard02.png : on the right, the 
original image and on the left, the resulting output.

  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...

  So if anyone could help or suggest anything, he will be welcome !!!

  Thanks in advance,

  Benoît


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