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cite="mid:1C9079C90336A64BBF5612428BC98E1F1F726838FA@ES04SNLNT.srn.sandia.gov"
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<pre wrap="">I was (naively?) hoping to hide all the different coordinate systems in
a utility library like PROJ.4 instead of implementing each one (there are
*tons* of them) as its own distinct subclass of vtkCoordinateSystem the
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Absolutely. I made the class that I referred to because we needed to
drive around in a van with a GPS receiver and display the map data
around us, including the 3D buildings etc for measurements - where all
was specified in OSGB coords. The UK transformation is annoying because
the 1997 version includes special 'lookuptables' which correct for
errors which were made in the 1936 'official' mapping where grids were
not completely regular. This kind of 'exception' to the standard
projection/ellipsoid/nonsense makes it hard to create a very general
purpose <i>any to any</i> coordinate transformation.<br>
<br>
My experience with proj.4 is limited I remember reviewing it in the
late 1990s when I was working in that field - I suspect it can do most
stuff that the majority of users need. If you poke around with any of
these vtkGeography classes etc and there is a swiss grid transformation
implemented, please let me know. We have terrain data and climate stuff
that would look good blended.<br>
<br>
cheers<br>
<br>
JB<br>
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cite="mid:1C9079C90336A64BBF5612428BC98E1F1F726838FA@ES04SNLNT.srn.sandia.gov"
type="cite">
<pre wrap="">way vtkGeography appears to. My (to date cursory) review of PROJ.4
made me think that many of these datums can be compiled into the library
but perhaps it doesn't choose the most numerically stable way to transform
coordinates from one system to another?
David
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<pre class="moz-signature" cols="78">--
John Biddiscombe, email:biddisco @ cscs.ch
<a class="moz-txt-link-freetext" href="http://www.cscs.ch/about/BJohn.php">http://www.cscs.ch/about/BJohn.php</a>
CSCS, Swiss National Supercomputing Centre | Tel: +41 (91) 610.82.07
Via Cantonale, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82</pre>
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