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  Sphere inversions (1/3) [112K] (Message 1 to 25 of 25)  
From: Florian Brucker
Subject: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 11:10:40
Message: <45d5d780@news.povray.org>
Hi!

Here are some sphere inversions I've done recently, of course inspired
by what scam [1] and Paul Bourke [2] did. I've used isosurfaces, meshes
and sphere sweeps, depending on the original geometry. Aside from the 3
I'm posting here, there are some more on [3], including my version of
the "RSOCP of sphere inversion", the Truchet tiling :)

Comments welcome!


[1]http://news.povray.org/web.447c45efc019fdb45c947f990%40news.povray.org
[2]http://local.wasp.uwa.edu.au/~pbourke/surfaces_curves/truchet/
[3]http://www.torfbold.com/external/si.html


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From: Florian Brucker
Subject: Sphere inversions (2/3) [112K]
Date: 16 Feb 2007 11:11:35
Message: <45d5d7b7@news.povray.org>



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From: Florian Brucker
Subject: Re: Sphere inversions (3/3) [82K]
Date: 16 Feb 2007 11:12:02
Message: <45d5d7d2@news.povray.org>



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From: Jim Charter
Subject: Re: Sphere inversions (2/3) [112K]
Date: 16 Feb 2007 14:36:06
Message: <45d607a6$1@news.povray.org>
Florian Brucker wrote:
> 
> ------------------------------------------------------------------------
> 
Wow! I have always disliked Menger Sponge renders,... until now.  Superb!


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From: Orchid XP v3
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 14:39:58
Message: <45d6088e@news.povray.org>
...now in the name of God do you "invert" a sphere?


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From: Charles C
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 15:25:00
Message: <web.45d6124e2d8cd81b7d5894630@news.povray.org>
Orchid XP v3 <voi### [at] devnull> wrote:
> ...now in the name of God do you "invert" a sphere?

Roll over Pluto!  Good boy.


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From: Charles C
Subject: Re: Sphere inversions (2/3) [112K]
Date: 16 Feb 2007 15:25:01
Message: <web.45d612ceb46ebe1a7d5894630@news.povray.org>
#2 of 3 makes me somehow want to see a fly-through :)

Florian Brucker <tor### [at] torfboldcom> wrote:
>


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From: Ross
Subject: Re: Sphere inversions (2/3) [112K]
Date: 16 Feb 2007 16:15:19
Message: <45d61ee7$1@news.povray.org>
"Charles C" <nomail@nomail> wrote in message
news:web.45d612ceb46ebe1a7d5894630@news.povray.org...
> #2 of 3 makes me somehow want to see a fly-through :)
>

or pour water through it


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From: Florian Brucker
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 16:40:04
Message: <45d624b4$1@news.povray.org>



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From: stm31415
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 18:15:00
Message: <web.45d63a202d8cd81bcf1900cc0@news.povray.org>
OOH! I like these. I think my favorites are the grid (#1) and the toruses
(#4 on the site).

Orchid XP v3: As I recall, a spherical inversion is not actually inverting
the *sphere*, as it is reflecting points across the surface of a sphere.
It's easier to imagine in two dimensions (see Escher); but the idea is that
for any point outside the sphere, there is a corresponding point inside the
circle. The closer to the surface of the sphere on the outside, the closer
tot eh surface of the sphere on the inside. The further away (i.e. closer
to infinite distance) the closer you get to the center of the sphere. So
infinite space is represented inside a finite volume --- so number one, if
you un-inverted it (same as re-inverting) would --- correct me if I'm wrong
--- be a rectangular grid stretching across all of space. The others
actually began with objects inside the spherical radius, so they end up
outside the sphere, and as none of the affected points were at the center
of the circle, there are no infinites involved.
A funny idea I just had --- a spherical inversion of a sufficiently small
concentric sphere (that started on the inside) would contain any given
point outside. So you could be outside the original, and inside the
inversion --- but still only see one side of the sphere. I think that means
that infinity only has one side ;)


Sam Bleckley
http://enso.freeshell.org/


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From: scam
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 21:15:00
Message: <web.45d664852d8cd81be4ce1bd60@news.povray.org>
Hi Florian, these are very nice, well done! Glad to see I wasn't the only
one mesmerized by these objects.

You've inspired me to have another look at these things, so I'll try and
come up with something interesting to post.

By the way, if anyone is interested in the code I used to generate my
version Florian referenced above, it's available here:
http://news.povray.org/web.447d804452ae62aa5c947f990%40news.povray.org

Cheers,

Sam (aka scam)


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From: Tor Olav Kristensen
Subject: Re: Sphere inversions (1/3) [112K]
Date: 16 Feb 2007 22:25:34
Message: <45d675ae$1@news.povray.org>
Florian Brucker wrote:
> Hi!
> 
> Here are some sphere inversions I've done recently, of course inspired
> by what scam [1] and Paul Bourke [2] did. I've used isosurfaces, meshes
> and sphere sweeps, depending on the original geometry. Aside from the 3
> I'm posting here, there are some more on [3], including my version of
> the "RSOCP of sphere inversion", the Truchet tiling :)
> 
> Comments welcome!
...

Here's two similar ones:

http://home.online.no/~t-o-k/POV-Ray_Images/Isosurface_Sphere_Inversion.jpg
http://home.online.no/~t-o-k/POV-Ray_Images/Isosurface_Circle_Inversion.jpg

-But I like your texture and light setting better !

-- 
Tor Olav
http://subcube.net


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From: Florian Brucker
Subject: Re: Sphere inversions (1/3) [112K]
Date: 17 Feb 2007 04:53:26
Message: <45d6d096$1@news.povray.org>



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From: Florian Brucker
Subject: Re: Sphere inversions (2/3) [112K]
Date: 17 Feb 2007 04:56:34
Message: <45d6d152$1@news.povray.org>



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From: Orchid XP v3
Subject: Re: Sphere inversions (1/3) [112K]
Date: 17 Feb 2007 06:11:12
Message: <45d6e2d0$1@news.povray.org>
So... is that something like taking the reciprocol of a complex number?


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From: scam
Subject: Re: Sphere inversions (1/3) [112K]
Date: 17 Feb 2007 06:35:01
Message: <web.45d6e7d12d8cd81be4ce1bd60@news.povray.org>
Orchid XP v3 <voi### [at] devnull> wrote:
> So... is that something like taking the reciprocol of a complex number?

Here's a good introduction in 2D:
http://mathworld.wolfram.com/Inversion.html


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From: Orchid XP v3
Subject: Re: Sphere inversions (1/3) [112K]
Date: 17 Feb 2007 07:24:12
Message: <45d6f3ec$1@news.povray.org>
>> So... is that something like taking the reciprocol of a complex number?
> 
> Here's a good introduction in 2D:
> http://mathworld.wolfram.com/Inversion.html

http://mathworld.wolfram.com/Reciprocal.html

Seems to indicate that the reciprocal of a complex number is indeed an 
inversion with respect to the unit circle in the complex plane.


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From: Tor Olav Kristensen
Subject: Re: Sphere inversions (1/3) [112K]
Date: 18 Feb 2007 19:45:17
Message: <45d8f31d$1@news.povray.org>
Florian Brucker wrote:
> Hi Tor!
> 
> Tor Olav Kristensen wrote:
>> Here's two similar ones:
> Ah, I've seen them before, but I forgot about them! The geometry is
> nice, what's the original structure?

It's a "straight" version of the isosurface used in this image:
http://hof.povray.org/Isosurface-Cubic_Space_Division.html

That structure looks similar to the one in the image in this post:

http://news.povray.org/3A21093C.4D45881A%40online.no
"Cubic Sphere Inversion" (21 Jan. 2004 to p.b.i.)

-- 
Tor Olav
http://subcube.net


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From: Eero Ahonen
Subject: Re: Sphere inversions (2/3) [112K]
Date: 19 Feb 2007 11:02:00
Message: <45d9c9f8@news.povray.org>
Florian Brucker wrote:
> The water would be the ultimate render time killer, I guess.

Transparency, ior and radiosity -compilation is also pretty good one ;).

-- 
Eero "Aero" Ahonen
   http://www.zbxt.net
      aer### [at] removethiszbxtnetinvalid


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From: bob from oz
Subject: Re: Sphere inversions (2/3) [112K]
Date: 21 Feb 2007 05:19:24
Message: <45dc1cac@news.povray.org>
Florian Brucker wrote:
> 
> ------------------------------------------------------------------------
> 

nice. this is quite pleasing to the eye

bob


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From: Florian Brucker
Subject: Re: Sphere inversions (2/3) [112K]
Date: 23 Feb 2007 05:48:44
Message: <45dec68c$1@news.povray.org>



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From: Eero Ahonen
Subject: Re: Sphere inversions (2/3) [112K]
Date: 23 Feb 2007 11:09:14
Message: <45df11aa$1@news.povray.org>
Florian Brucker wrote:
> Eero Ahonen wrote:
>> Florian Brucker wrote:
>>> The water would be the ultimate render time killer, I guess.
>> Transparency, ior and radiosity -compilation is also pretty good one ;).
> 
> Yep, but that's you Aero, nobody else is that crazy :P
> 

But hey, craziness is my trademark in such things. May I show the
textured versions of your inversions (well, I only have Torinet so far,
but I _will_ trace more:) here?

BTW, I'm still tracing my CGSphere draft's next version, THIS is getting
a bit too slow to get something done...

232:09:11 Rendering line 116 of 768, 4896 supersamples, 22577 rad. samples

-- 
Eero "Aero" Ahonen
   http://www.zbxt.net
      aer### [at] removethiszbxtnetinvalid


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From: Florian Brucker
Subject: Re: Sphere inversions (2/3) [112K]
Date: 23 Feb 2007 12:15:43
Message: <45df213f$1@news.povray.org>



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From: Eero Ahonen
Subject: Re: Sphere inversions (2/3) [50KiB]
Date: 23 Feb 2007 17:40:59
Message: <45df6d7b@news.povray.org>
Florian Brucker wrote:
> 
> Sure, show it! It's always interesting to see what different people make
> out of the same underlying concept :)
> 

Great :). Here's the red and transparent version of Torinet...

-- 
Eero "Aero" Ahonen
   http://www.zbxt.net
      aer### [at] removethiszbxtnetinvalid


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From: Eero Ahonen
Subject: Re: Sphere inversions (2/3) [51KiB]
Date: 23 Feb 2007 17:41:10
Message: <45df6d86@news.povray.org>



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