I have now found the source for Marching Cubes on the Web, written by Mike
Chupa.
Unusually for 'acquired' code it only needed minor mods to get it to run on
Windoze
and to produce mesh2 data instead of OpenInventor. So, here is the MR scan
from
http://graphics.stanford.edu/data/voldata/ rendered as an iso-surface at
depth 80.
The mesh2 ascii file is 63.8MB and takes over 1 1/2 minutes to parse but
only
seconds to render, very impressive!
Both subjects are male, I believe, but I've named them both Edna anyway  8-)

Andy

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Attachments:
Download 'MRHeadIso.jpg' (11 KB)

Preview of image 'MRHeadIso.jpg'

Very impressive.  I do stuff like this only in my dreams.

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in news:3e3dab7a@news.povray.org A J Le Couteur Bisson wrote:

> The mesh2 ascii file is 63.8MB and takes over 1 1/2 minutes to parse but
> only

Have you also tried to render the df3 as an isosurface directly?

Ingo

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"ingo" <ing### [at] tagpovrayorg> wrote in message
news:Xns### [at] povrayorg...
> in news:3e3dab7a@news.povray.org A J Le Couteur Bisson wrote:
>
> > The mesh2 ascii file is 63.8MB and takes over 1 1/2 minutes to parse but
> > only
>
> Have you also tried to render the df3 as an isosurface directly?
>
> Ingo

Thought about it, then thought about getting the precise syntax right and
how long it
would take to render and started looking for marching cubes code.....

Heres the last image of this series (honest.)
The CT head rendered at an iso-surface level of 100 (out of 255) and
sectioned.
Good for checking the inside of Edna's skull!

Enjoy, (if you like this sort of thing!)

Andy

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Attachments:
Download 'Sectioned-CTHeadIso-100.jpg' (37 KB)

Preview of image 'Sectioned-CTHeadIso-100.jpg'

> Thought about it, then thought about getting the precise syntax right and
> how long it
> would take to render and started looking for marching cubes code.....

Oh, and I didn't know if the .df3 interpolation would provide a suitable
gradient for the iso-surface calculations to work properly.  Has anyone
tried this?

Andy

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in news:3e3e47f1@news.povray.org A J Le Couteur Bisson wrote:

> Oh, and I didn't know if the .df3 interpolation would provide a
> suitable gradient for the iso-surface calculations to work properly. 
> Has anyone tried this?
> 

Below is a snippet of code I used on frog dataset:


#declare F1=   function {
      pattern {
         density_file df3 "frog.df3"
         interpolate 1
         translate -0.5
      }
   }


isosurface{
   function {
      -F1(x,y,z)
   }
   contained_by {box{-0.5,0.5}}
   threshold -0.515
   accuracy 0.0000001
   max_gradient 145
   scale<500/500,470/500,138/500>
   scale 4
   pigment {rgb 1}
}


Ingo

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A J Le Couteur Bisson wrote:
> Enjoy, (if you like this sort of thing!)

You have *got* to animate this :)


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Rick

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"ingo" <ing### [at] tagpovrayorg> wrote in message
news:Xns### [at] povrayorg...
> in news:3e3e47f1@news.povray.org A J Le Couteur Bisson wrote:
>
> > Oh, and I didn't know if the .df3 interpolation would provide a
> > suitable gradient for the iso-surface calculations to work properly.
> > Has anyone tried this?
> >
>
> Below is a <snip>      :)

Thanks, I'll give it a go.

Andy

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"Rick [Kitty5]" <ric### [at] kitty5com> wrote in message
news:3e3e591c$1@news.povray.org...
> A J Le Couteur Bisson wrote:
> > Enjoy, (if you like this sort of thing!)
>
> You have *got* to animate this :)

I can see it now, the head rotating and the sectioning plane static.....

I have a web-site (currently suffering from 5 years neglect!) which I am
revamping at this very
moment (so it will be ready in 5 yrs time :)
I am including a POVRay section so I will put the df3 files and the Marching
Cubes code there
along with some images.

Its www.abisson.co.uk but I really wouldn't bother at the mo unless you are
interested in my own
'Aurora raytracer classes for C++' and even these will have minor updates.
Check it in a week or two.

Andy

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"A J Le Couteur Bisson" <and### [at] virginnet> wrote in message
news:3e3e76d1@news.povray.org...
>
> "Rick [Kitty5]" <ric### [at] kitty5com> wrote in message
> news:3e3e591c$1@news.povray.org...
> > A J Le Couteur Bisson wrote:
> > > Enjoy, (if you like this sort of thing!)
> >
> > You have *got* to animate this :)
>
> I can see it now, the head rotating and the sectioning plane static.....
>
> I have a web-site (currently suffering from 5 years neglect!) which I am
> revamping at this very
> moment (so it will be ready in 5 yrs time :)
> I am including a POVRay section so I will put the df3 files and the
Marching
> Cubes code there
> along with some images.
>
Its up!  But for the time being its at www.btinternet.com/~ajlcb/povray.html
I 'm not sure I have room for the .df3 files but the Marching Cubes code,
including a Windows binary, are there.

Andy

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