[vtkusers] Interpolating point on a surface

[David Doria]

On Thu, Jan 21, 2010 at 2:13 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> Ken,
>
> I enhanced David D's example:
> http://www.vtk.org/Wiki/VTK/Examples/InterpolateTerrain
> to use the vtkCellLocator as well as the vtkProbeFilter. If your data
> is uniformly spaced in a grid, then the ProbeFilter is appropriate. If
> it is not uniform in x,y, then the CellLocator is what you want.
>
> Bill
>
> On Thu, Jan 21, 2010 at 11:13 AM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
> > Ken,
> >
> > I think you want:
> > Filtering/vtkCellLocator. It has a method:
> >  // Description:
> >  // Return intersection point (if any) AND the cell which was intersected
> by
> >  // the finite line. The cell is returned as a cell id and as a generic
> cell.
> >  // For other IntersectWithLine signatures, see vtkAbstractCellLocator
> >  virtual int IntersectWithLine(double a0[3], double a1[3], double tol,
> >                                double& t, double x[3], double pcoords[3],
> >                                int &subId, vtkIdType &cellId,
> >                                vtkGenericCell *cell);
> >
> > Just specify a large positive and negative Z for your lines.
> >
> > BTW, the sample looks like a golf green It it is, you may enjoy this
> > paper I wrote with a colleague in 1992.
> >
> > Lorensen, W. E. and B. Yamrom, Golf Green Visualization, IEEE Computer
> > Graphics and Applications, vol. 12, no. 4, pp. 35-44, 1992.
> > http://marchingcubes.org/images/6/6f/GolfGreenVisualization.pdf
> >
> > Bill
> >
> > On Tue, Jan 19, 2010 at 7:02 PM, Kenneth Porter <shiva at sewingwitch.com>
> wrote:
> >> --On Tuesday, January 19, 2010 1:21 AM -0500 Darshan Pai
> >> <darshanpai at gmail.com> wrote:
> >>
> >>> I am not exactly sure what you are asking .
> >>> maybe you can try the FindPoint() function in vtkPolyData....
> >>
> >> Imagine that I'm given a topo map and know latitude and longitude, and
> need
> >> to calculate the altitude.
> >>
> >> It looks like FindCell might do what I need:
> >>
> >> <
> http://www.vtk.org/doc/nightly/html/classvtkDataSet.html#a2221c10d3c4cca44e82c5ef70e4e1cbd
> >
> >>
> >> I need to find the triangle that contains an X/Y point, where the Z is
> >> unknown, so that I can compute the Z.
> >> _______________________________________________
> >> Powered by www.kitware.com
> >>
> >> Visit other Kitware open-source projects at
> >> http://www.kitware.com/opensource/opensource.html
> >>
>
>
Why does the data have to be uniformly spaced on a grid for the
vtkProbeFilter? The documentation (
http://www.vtk.org/doc/nightly/html/classvtkProbeFilter.html#_details) says
"For example, an unstructured grid
(vtkUnstructuredGrid<classvtkUnstructuredGrid.html>)
can be probed with a volume
(three-dimensionalvtkImageData<classvtkImageData.html>
)"

Thanks,

David
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20100121/112bb137/attachment.htm>