ray casting with surface geometry

[Dimitris Agrafiotis]

Dear All

I have the following question.

I have two different volumetric datasets (both structured points) and 
using the sane renderer I render one of them using ray casting and from
the other I extract an opaque surface (triangles) using a contouring 
filter (e.g. marching cubes). I am not sure about the result I am 
taking. Are the rays bounded by the surface? Or does the renderer just 
ray cast the whole volume, produces the pixel values, then constructs 
the surface geometry and the pixel values for the other dataset and 
then composites the resulting pixel arrays? And wouldn't the second 
case be incorrect since the rays would have taken in consideration 
points that are not actually visible?

If I want to bound the rays do I have to use the 
vtkProjectedPolyDataRayBounder object?

Finally, I am using vtk 2.4. If I switched to vtk 3.1 and used the 
TextureMapper2D for the ray casting part would then everything be OK?

Please forgive me if there is something fundamentally wrong in what I am
saying. 

Thanks in Advance 
Dimitris


----------------------
Dimitris Agrafiotis
University of Bristol
Department of Electrical & Electronic Engineering
Merchant Venturers Building 
Woodland Road, Bristol BS8 1UB, UK
Phone:  (+ 44 117) 9545194
E-mail: d.agrafiotis at bristol.ac.uk

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