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and also check out vtkGeography where much has already been done.<br>
<a class="moz-txt-link-freetext" href="http://www.cs.uno.edu/~maik/vtkGeography/index.html">http://www.cs.uno.edu/~maik/vtkGeography/index.html</a><br>
<br>
JB<br>
PS. I also have some old (but accurate) code which implements the UK
National grid to <br>
// .NAME vtkGPSToOSGB36 - Convert WGS84 GPS coords to OSGB using OSTN97
transformation correction to give precise OSGB36 coordinates<br>
<br>
<blockquote cite="mid:1198108811.22209.216.camel@beaker.ran.sandia.gov"
type="cite">
<pre wrap="">Hi,
We've been looking at information visualization of graphs with a
"geographic" placement strategy in combination with geographic raster
and vector data and are thus also looking at how to handle various
projections/datums. Have either of you considered PROJ.4
(<a class="moz-txt-link-freetext" href="http://proj.maptools.org/">http://proj.maptools.org/</a> )? It appears to handle many common (and some
uncommon) projections and has an X/MIT-style license.
David
--
David Thompson, MS 9152 (925)294-2537
Sandia National Laboratories <a class="moz-txt-link-abbreviated" href="mailto:dcthomp@sandia.gov">dcthomp@sandia.gov</a>
Distributed Visualization Systems 8963 Bldg/Rm 915/N144
PO Box 969, Livermore, CA 94551-0969
On Wed, 2007-12-19 at 09:19 -0700, Philip Schuchardt wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Tuesday 18 December 2007 6:39 pm, Andrew Maclean wrote:
</pre>
<blockquote type="cite">
<pre wrap="">It may be a good idea but will involve a lot of work.
Are you using Moldensky transforms or Readfern for Lat/Long to UTM?
</pre>
</blockquote>
<pre wrap="">Currently, neither. I only begun to play round with the idea.
</pre>
<blockquote type="cite">
<pre wrap="">Also
for ECEF (Earth-centered fixed Cartesian coordinates) to Lat/Long you may
like to look at K.M.Borkowski's work. He found a closed form solution. Also
UTM to Lat/Long needs to handle the exceptions near Norway and and to
handle coordinates near the edges of the grid.
You will most likley need to also do inverse and forward transforms using
Vincenty's equations.
Remember to be applicable inVTK iit needs to be world wide and there are
meny coordinate systems out there. So you will need the classes to be
extensible.
</pre>
</blockquote>
<pre wrap="">I was planning on designing GeocoordinateProperty to be extendable for any
coordinate system. It does seem that I have a lot of work to do. Thanks for
the insight.
Philip Schuchardt
</pre>
<blockquote type="cite">
<pre wrap="">
You will also need to specify the accuracy of the transforms.
Andrew
On Dec 19, 2007 8:18 AM, Philip Schuchardt <a class="moz-txt-link-rfc2396E" href="mailto:ohc@vt.edu"><ohc@vt.edu></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hello,
I would like to thank you all for all your hard work. I love the well
thought
out vtk pipeline.
I'm developing CaveWhere(<a class="moz-txt-link-abbreviated" href="http://www.cavewhere.org">www.cavewhere.org</a>) and I'm currently using vtk
and
wxWidgets to model underground cave systems. I have also modified and
developed some useful filter and fixes to vtk. I would like to
contribute to
the vtk project. I'm just wonding, if your interested in:
-- Geocoordinate System Filter --
I work with many geographical coordinate systems (UTM, Stateplane, Lat
Long,
etc.). I currently working on a filter that takes polydata and
transforms the data to match current geographic projection(ie. world
coordinates). All
geocoordinate filters work together to scale and offset all the data
around
the origin. Scaling and offsetting the data around the origin, reduces
Z-Buffer persion errors. Filter's properties will modified by a
GeocoordinateProperty*. GeocoordinateProperty allow multiple filters to
share
the same geographical coordinate system. I believe this class would be
useful for anyone doing geo-spatial visualizations.
-- 2D Text Manager --
I've written a class that managers 3D anchored, 2D text actors. It keeps
multiple text actors from overlapping each other. It also support
Z-buffer
checking, which keeps "hidden" 2D text actors from showing.
I've also had performance issues while displaying 100's of 2D text
actors, at
once. I think it's a openGL pipeline issue. Does vtk/ftgl use display
lists
for 2D text actors? If it doesn't, I think display lists would greatly
improved 2D text actors rendering performance.
-- Buffered Hardware Picking --
Also, I've noticed that vtk doesn't support buffered hardware picking.
In vtkOpenGLCamera.cxx
vtkgluPickMatrix(ren->GetPickX(), ren->GetPickY(), 1, 1, lowerLeft,
size);
1,1 - States that the buffer is 1 pixel by 1 pixel. This small buffer
makes
it very difficult to select lines or points. In my project I have
extended
the vtkOpenGLCamera to support buffer greater then 1 by 1 pixels.
If you like one or more of the ideas please email me back. I will
definitely,
work on getting my code up VTK specifications.
Thanks,
Philip Schuchardt
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</pre>
</blockquote>
</blockquote>
<pre wrap="">_______________________________________________
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</pre>
</blockquote>
<pre wrap=""><!---->
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</pre>
</blockquote>
<br>
<br>
<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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