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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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