[vtkusers] Alternatives to vtkCellPicker

[murali dhanakoti]

Hello,


I have a vtkPolyData with ~2000 points and ~4000 triangles that I'm
rendering. I'm using vtkCellPicker to shoot 400 rays and would like to know
the coordinates of the rendered polydata with which these rays intersect and
also I want to know the cells that intersected with these rays.
vtkCellPicker seems to do the right thing (i.e., it returns the correct
intersection points and intersecting cell ids), but it takes a long time to
run. With the use of vtkTimerLog, I find that it takes on an average 1.5
seconds to perform these 400 ray intersections with my 4000 triangle model.
This time is not acceptable since I am working with a sparse data now and
ulitmately my code would likely be running with much larger models.

So, I would like to know a couple of things

a) Normally, does vtkCellPicker's Pick() take this long? (I have verified
that the other parts of my code are not slowing things down)
b) If so, what type of speed up mechanisms do you use in your vtk apps?

I saw vtkCellLocator uses an octree to speed up location queries? Should I
be using it's IntersectWithLine function and avoid vtkCellPicker? Are there
any other alternatives?

-- 
Regards,
Murali Dhanakoti
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