Warp wrote:
> lien <nomail@nomail> wrote:
>> what i want is the volume raytracing technique based feature in povray.
>> I know that we can render the implicit iso-surface by using the existing
>> keyword "isosurface" in povray, but it seems that it is based on some
>> technique like Marching Cube, which first extraction the geometry of the
>> iso-surface. But with volume raytracing technique, we can directly raytrace
>> the volume data and save the geometry extracting step.
> 
>   Isosurfaces don't use anything like marching cubes, and I don't really
> understand what is the relation between isosurfaces and volume raytracing.

Volume data from medical imaging techniques measures densities. Everything
else you see, i.e. specific organs, is the result of clever post processing
in conjunction with contrast enhancing substances the human received. Thus,
if you want to extract specific information you can use isosurfaces by
defining their threshold to the desired density.

Regarding the original post, to use the data, it has to be converted to a
POV-Ray density file. This file can then be turned into a pattern, which can
be used in an isosurface for rendering. In fact, the original isosurface
patch website (iirc that page is no longer available) had a sample image of
a human head.

	Thorsten

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