[vtkusers] Interpolating point on a surface

[Bill Lorensen]

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.
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