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<DIV><SPAN class=388594717-28102010><FONT size=2>When you use "gdalwarp -tps"
what is the practical limit to the number of GCPs useable in the thin plate
spline algorithm before the program bogs down.</FONT></SPAN></DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2>I would like to use it
with over 1600 spline knots spread over the image.</FONT></SPAN></DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2>Currently on a X86_64 smp linux
system with 4 cores and 8 cpus and "-multi" turned on, 1600 knots takes
about 30 min. As far as I can gather from experimenting with the
# of knots, most of this time is spent with either solving for the spline
weights or generating the spline kernel.</FONT></SPAN></DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2>Who can shed some light on what
is going on under the hood here? Is the spline kernel being calculated
on-the-fly for every pixel in the image? What method of solving for the weights
is being used, and can it handle very large sparse matrices?</FONT></SPAN></DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2>Thanks,</FONT></SPAN></DIV>
<DIV><SPAN class=388594717-28102010><FONT size=2>
Max</FONT></SPAN></DIV>
<DIV><SPAN style="FONT-SIZE: 10pt"></SPAN> </DIV>
<DIV><SPAN style="FONT-SIZE: 10pt">------------------<BR>Max Buchheit<BR>Canada
Centre for Remote Sensing / Centre <SPAN class=SpellE>Canadien</SPAN> de <SPAN
class=SpellE>Télédétection</SPAN><BR>Earth Sciences Sector / <SPAN
class=SpellE>Secteur</SPAN> des Sciences de la Terre<BR>Natural Resources Canada
/ <SPAN class=SpellE>Ressources</SPAN> <SPAN class=SpellE>Naturelles</SPAN>
Canada<BR>4th Floor, 588 Booth Street / 4-ieme <SPAN
class=SpellE>étage</SPAN>, 588 rue Booth<BR>Ottawa, Ontario, K1A 0Y7<BR>Phone:
(613) 943-7444/ Email: mbuchhei at nrcan.gc.ca<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></DIV>
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