[vtkusers] Ray Bounding ...

[Lisa S. Avila]

Hello Hari,

The vtkRayBounder class is abstract. You should use 
vtkProjectedPolyDataBounder. You give the bounder a vtk polydata as the 
input and this will be used to bound the rays (nearest and farthest 
intersection point with the polydata). This means it is an exact clipping 
for convex polyhedra such as a sphere or a box, but can be used for 
space-leaping with non-convex polyhedra. For example, you may use a 
contouring algorithm to extract an isosurface at 50 if you know that your 
transfer function has an opacity of 0.0 for all scalar values below 75. 
There is a pretty good chance that the entire interesting (non-zero) 
portion of the volume lies within the 50 isosurface (that would be a 100% 
chance if the isosurface were exact, but it is only an approximation).

Good luck.

Lisa


At 02:26 PM 12/12/2000, Hari Sundar wrote:
>Hi,
>
>I want to implement a "space-leaping" algorithm so that Volume Ray Casting
>can be made faster. I plan to use the vtkRayBounder or the
>vtkProjectedPolyDataBounder classes. Can someone help me out on this by
>sending a few examples on using vtkRayBounder.
>
>Thanks,
>
>Hari
>
>
>
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