[vtk-developers] Geocoordinate System Filter, 2D Text Manager,2D Text Preformance, and Buffered Hardware Picking

[Thompson, David C]

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
(http://proj.maptools.org/ )? 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           dcthomp at sandia.gov
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:
> On Tuesday 18 December 2007 6:39 pm, Andrew Maclean wrote:
> > 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?
>
> Currently, neither.  I only begun to play round with the idea.
>
> > 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.
>
> 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
>
> >
> >
> > You will also need to specify the accuracy of the transforms.
> >
> >
> >
> > Andrew
> >
> > On Dec 19, 2007 8:18 AM, Philip Schuchardt <ohc at vt.edu> wrote:
> > > 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(www.cavewhere.org) 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
> > > _______________________________________________
> > > vtk-developers mailing list
> > > vtk-developers at vtk.org
> > > http://www.vtk.org/mailman/listinfo/vtk-developers
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