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28 Mar 2024 19:14:49 EDT (-0400)
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From: Tor Olav Kristensen
Subject: Re: The Superellipsoidal Brain
Date: 15 Jan 2019 21:55:01
Message: <web.5c3e9c663a551e31264be49d0@news.povray.org>
"And" <49341109@ntnu.edu.tw> wrote:
>...
>
> Very pretty.

Thank you And !

--
Tor Olav
http://subcube.com


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From: Bald Eagle
Subject: Re: The Superellipsoidal Brain
Date: 15 Jan 2019 23:25:01
Message: <web.5c3eb1113a551e31765e06870@news.povray.org>
"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
> Here's an image I made a while ago.

> All
> these superellipsoids were made with a single isosurface statement.

Whoa!
That's pretty cool!  :)

Have you tried experimenting with making them "supershapes"?

Good to see you dropping in, and dropping more mind-bending [sic] projects on
us.


May 2019 see many more   :)


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From: ingo
Subject: Re: The Superellipsoidal Brain
Date: 16 Jan 2019 02:04:06
Message: <XnsA9D952139821Aseed7@news.povray.org>
in news:web.5c3e1168d8b92d66a09309da0@news.povray.org Tor Olav Kristensen 
wrote:

> Here's an image I made a while ago

Oh yes. A fossilised amber brain.

ingo


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From: Paolo Gibellini
Subject: Re: The Superellipsoidal Brain
Date: 16 Jan 2019 04:19:24
Message: <5c3ef71c$1@news.povray.org>
Tor Olav Kristensen wrote on 15/01/2019 18:06:
> Here's an image I made a while ago.
> 
> I got the data for the brain from Paul Bourke's file mri.df3, that can be found
> in the file mri.tar.gz available at this page:
> http://paulbourke.net/miscellaneous/povexamples/
> 
> All the voxels with a density above a certain threshold are filled with a
> superellipsoid with a color corresponding to the density in each voxel. All
> these superellipsoids were made with a single isosurface statement.
> 
> The colors were borrowed from the Inferno color map in Matplotlib:
> https://matplotlib.org/examples/color/colormaps_reference.html
> 
> --
> Tor Olav
> http://subcube.com
> 
The discrete state of thinking... a nice image,
;-)
  Paolo


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From: Norbert Kern
Subject: Re: The Superellipsoidal Brain
Date: 16 Jan 2019 06:55:01
Message: <web.5c3f1a9f3a551e311fbfafc10@news.povray.org>
"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
> Here's an image I made a while ago.
>
> I got the data for the brain from Paul Bourke's file mri.df3, that can be found
> in the file mri.tar.gz available at this page:
> http://paulbourke.net/miscellaneous/povexamples/
>
> All the voxels with a density above a certain threshold are filled with a
> superellipsoid with a color corresponding to the density in each voxel. All
> these superellipsoids were made with a single isosurface statement.
>
> The colors were borrowed from the Inferno color map in Matplotlib:
> https://matplotlib.org/examples/color/colormaps_reference.html
>
> --
> Tor Olav
> http://subcube.com


Much better than my own approach to depict mri scans.
How did you remove bones, eyes etc.?

Norbert


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From: Tor Olav Kristensen
Subject: Re: The Superellipsoidal Brain
Date: 18 Jan 2019 19:20:01
Message: <web.5c426ca33a551e31264be49d0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
> > Here's an image I made a while ago.
>
> > All
> > these superellipsoids were made with a single isosurface statement.
>
> Whoa!
> That's pretty cool!  :)

Thank you Bill !


> Have you tried experimenting with making them "supershapes"?

I had forgotten about the supershapes, so I searched for them
- and ended up at one of Paul Bourke's web pages again:
http://paulbourke.net/geometry/supershape/

I see now that there's two files there that I've made; ss_macro1.inc &
example1.pov
- So apparently I have been experimenting with them once...

It seems that they are commonly made with parametric meshes. Perhaps it is
possible to model some of them as isosurfaces. But that would be very slow, so I
think I'll wait some years (for more computing power) before looking into that.


> Good to see you dropping in, and dropping more mind-bending [sic] projects on
> us.
>
>
> May 2019 see many more   :)

=)

For a long while I have not had much time to work with POV-Ray, so I hope that I
will have more time for it soon.

--
Tor Olav
http://subcube.com


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From: Tor Olav Kristensen
Subject: Re: The Superellipsoidal Brain
Date: 18 Jan 2019 19:30:00
Message: <web.5c426f143a551e31264be49d0@news.povray.org>
ingo <ing### [at] tagpovrayorg> wrote:
> in news:web.5c3e1168d8b92d66a09309da0@news.povray.org Tor Olav Kristensen
> wrote:
>
> > Here's an image I made a while ago
>
> Oh yes. A fossilised amber brain.

Hehe, you're right, it looks like amber. I hadn't thought about that.

- Then maybe there's some insects somewhere within it...

--
Tor Olav
http://subcube.com


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From: Tor Olav Kristensen
Subject: Re: The Superellipsoidal Brain
Date: 18 Jan 2019 19:40:01
Message: <web.5c4270dc3a551e31264be49d0@news.povray.org>
Paolo Gibellini <p.g### [at] gmailcom> wrote:
>...
>...
> The discrete state of thinking... a nice image,
> ;-)

Yes, that would be a very good title for it.

I'm glad you like it.

--
Tor Olav
http://subcube.com


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From: Tor Olav Kristensen
Subject: Re: The Superellipsoidal Brain
Date: 18 Jan 2019 20:10:01
Message: <web.5c4278043a551e31264be49d0@news.povray.org>
"Norbert Kern" <nor### [at] t-onlinede> wrote:
>
>...
> Much better than my own approach to depict mri scans.

I really like the way you have arranged the glass sheets and how the light
escapes at their edges.

BTW: Where did you find the MRI-data for this ?


> How did you remove bones, eyes etc.?

Luckily I did not have to deal with that. It had already been done, so the
DF3-file only contains the brain.

A while ago I made some (not very successful) attempts at filtering the data (in
Python) for a CT-scan according to a range of Hounsfield units for bone:
https://en.wikipedia.org/wiki/Hounsfield_scale

IIRC the problem was that the range for the bones overlapped the range for some
other tissue. (It might be that it wasn't a high quality scan.) I suspect that
they now use quite advanced techniques to isolate the different organs. I would
guess that some techniques find "gradient surfaces" in the data.

--
Tor Olav
http://subcube.com


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From: Bald Eagle
Subject: Re: The Superellipsoidal Brain
Date: 18 Jan 2019 21:40:00
Message: <web.5c428dd13a551e31765e06870@news.povray.org>
"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:

> I had forgotten about the supershapes, so I searched for them
> - and ended up at one of Paul Bourke's web pages again:
> http://paulbourke.net/geometry/supershape/
>
> I see now that there's two files there that I've made; ss_macro1.inc &
> example1.pov
> - So apparently I have been experimenting with them once...
>
> It seems that they are commonly made with parametric meshes. Perhaps it is
> possible to model some of them as isosurfaces. But that would be very slow, so I
> think I'll wait some years (for more computing power) before looking into that.

I did it in 8/2017 with isosurfaces, so I would imagine you could do an
approximation of some sort to speed it up.

Here's my see-them-all scene if you wanted some code to to run a quick test
scene:


#version 3.71;
global_settings {
 assumed_gamma 1.0
}

#include "colors.inc"





#declare m  =  7;  // number of lobes
#declare n1 =  5;
#declare n2 =  5;
#declare n3 =  5;
#declare a  =  1;
#declare b  =  1;

#declare M = 10;  // iterations

#declare AL = 20;
#declare L = 0.05;
cylinder {<-AL*4, 0, 0>, <AL*4, 0, 0>, L pigment {Red} no_shadow}
cylinder {<0, -AL*4, 0>, <0, AL*4, 0>, L pigment {Green} no_shadow}
cylinder {<0, 0, -AL*4>, <0, 0, AL*4>, L pigment {Blue} no_shadow}

camera {
  location <M*4, 0, -75>
  look_at  <0, 0, 0>
  right x*image_width/image_height
  up 1*y
}

#declare LS = <M*4, M*2, -100>;

light_source {LS color White}
cylinder {LS, <0, 0, 0>, 0.01 pigment {White} no_shadow}

#declare CB = 4;

#for (n1, 1, M)
 #for (n2, 1, M)
  #for (m, 1, M)
   isosurface {
    function {
     pow (
      pow (abs (cos (0.25 * m * acos (y/sqrt(x*x+y*y)) * abs(y)/y) / a), n2)  +
      pow (abs (sin (0.25 * m * acos (y/sqrt(x*x+y*y)) * abs(y)/y) / b), n3)
      , (1/n1)
     )
     //* sqrt (x*x+y*y) - 1 }
     * sqrt ((x*x)+(y*y)+(z*z)) - 1
    }

        contained_by { box { <-CB, -CB, -CB>, <CB, CB, CB> } }
        accuracy 0.01
        max_gradient 12
        scale <1, 1, 1>
        #declare Hue = m * (360/M);
        texture {pigment {color CHSV2RGB (rgb <Hue, 1, 1>)} finish {specular
0.2}}
        translate -x*M
        translate  x*m*3
        translate  y*M
        translate -y*n2*3
        translate -z*M
        translate  z*n1*3
   }

  #end // end for m
 #end // end for n2
#end // end for n1


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