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

[Philip Schuchardt]

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