[Gdal-dev] Thin Plate Spline Warper

[Frank Warmerdam]

Folks,

For some time people have noted that the GDAL polynomial image 
warper does not perform well for some images.  For instance long
AVHRR swaths. 

With code provided by VISRT Inc, and the financial support of the
Centro di Ecologia Alpina I have been able to incorporate a thin plate
spline warper into GDAL.  While I am still doing some testing, it seems
to be performing very well.  This transformer transforms exactly at all
ground control points provided, and between control points gives 
smooth (continuous) results with greatest weight given to nearby 
control points.  

The new thin plate spline warper can be used with gdalwarp by 
providing the -tps commandline switch.  It can be invoked
programatically using an order of -1 with GDALCreateGenImgProjTransformer
or more directly by invoking GDALCreateTPSTransformer(). 

I would encourage people to try it out from nightly snapshots of
GDAL (or from CVS).  Let me know if you run into problems. 

Also, while in working on transformers I have altered the way that
transformers work a bit with the intention of making the serialization
of warper information to XML work properly.  Previously it was broken
on win32 platforms due to problems comparing function pointers in win32
DLL builds.  That should all be resolved now.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent