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From: Bill Pragnell
Subject: Tetrahedral planetoid revisited
Date: 6 Feb 2008 06:20:00
Message: <web.47a99724ffed9a2731f01d10@news.povray.org>
Some of you may remember my Escher 'Double Planetoid' tribute from a couple of
years back. I've been playing with the rocky part of the planetoid, partly to
improve the realism of the rock and partly to make it render faster, because
I'm trying to render a large version to put on Zazzle (test renders at the
final resolution were starting to take weeks. Damn you, radiosity +
isosurface!)

I got hold of Jaap Frank's tweaking of Kevin Loney's isosurface approximation
macro, see

http://news.povray.org/povray.binaries.images/thread/%3C3f012665%40news.povray.org%3E/

for the original thread on this server. The tetrahedron below is built from
2,400 copies of the demo scene's wrinkled sphere mesh at <100,100,100>
resolution, and rendered in ~30 mins on my Macbook (peak memory ~22MB).

The idea is to suggest a normal spherical planetoid but with mountainous peaks
that more naturally form a tetrahedron shape. I think it's a very nice result
so I thought I'd share it!

Comments are of course welcome

Bill


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Attachments:
Download 'trisosurface.jpg' (200 KB)

Preview of image 'trisosurface.jpg'
trisosurface.jpg


 

From: gonzo
Subject: Re: Tetrahedral planetoid revisited
Date: 6 Feb 2008 16:30:01
Message: <web.47aa25f86181678ca0c272b50@news.povray.org>
"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> Some of you may remember my Escher 'Double Planetoid' tribute from a couple of
> years back. I've been playing with the rocky part of the planetoid, partly to
> improve the realism of the rock and partly to make it render faster, because
> I'm trying to render a large version to put on Zazzle (test renders at the
> final resolution were starting to take weeks. Damn you, radiosity +
> isosurface!)
>
> I got hold of Jaap Frank's tweaking of Kevin Loney's isosurface approximation
> macro, see
>
>
http://news.povray.org/povray.binaries.images/thread/%3C3f012665%40news.povray.org%3E/
>
> for the original thread on this server. The tetrahedron below is built from
> 2,400 copies of the demo scene's wrinkled sphere mesh at <100,100,100>
> resolution, and rendered in ~30 mins on my Macbook (peak memory ~22MB).
>
> The idea is to suggest a normal spherical planetoid but with mountainous peaks
> that more naturally form a tetrahedron shape. I think it's a very nice result
> so I thought I'd share it!
>
> Comments are of course welcome
>
> Bill

Must be a popular vacation planet for the rock climbing crowd!

RG


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From: Thomas de Groot
Subject: Re: Tetrahedral planetoid revisited
Date: 7 Feb 2008 05:41:43
Message: <47aae067$1@news.povray.org>
Your experiment reminds me that I tried Jaap Frank's macro a couple of years 
ago, but without satisfying results. I should experiment again, I guess. 
Good work Bill! ...and thanks for reminding me :-)

Thomas


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From: Jörg 'Yadgar' Bleimann
Subject: Re: Tetrahedral planetoid revisited
Date: 7 Feb 2008 07:28:43
Message: <47aaf97b$1@news.povray.org>
High!

Bill Pragnell schrieb:

> The idea is to suggest a normal spherical planetoid but with mountainous peaks
> that more naturally form a tetrahedron shape. I think it's a very nice result
> so I thought I'd share it!

Not very convincing - real asteroids, especially medium-sized to large, 
are far less rugged, as their shapes are smoothed by a thick layer of 
dust produced by billions of years worth of micrometeorite impacts.
Small asteroids, especially when they are "rubble piles" loosely held 
together by microgravity rather than massive solid bodies, can have a 
somewhat rougher surface, but still not as rough as your tetrahedron.

Just look here:

Asteroid (433) Eros:
http://nssdc.gsfc.nasa.gov/planetary/mission/near/near_eros.html

Asteroid (25143) Itokawa - only about 500 metres long!
http://www.bernd-leitenberger.de/hayabusa.shtml (German, but several 
good close-up photos of Itokawa!)

See you on www.khyberspace.de !

Yadgar


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid revisited
Date: 7 Feb 2008 07:45:01
Message: <web.47aafcd66181678c731f01d10@news.povray.org>
=?ISO-8859-1?Q?J=F6rg_=27Yadgar=27_Bleimann?= <yaz### [at] gmxde> wrote:
> Not very convincing - real asteroids, especially medium-sized to large,
> are far less rugged, as their shapes are smoothed by a thick layer of
> dust produced by billions of years worth of micrometeorite impacts.
> Small asteroids, especially when they are "rubble piles" loosely held
> together by microgravity rather than massive solid bodies, can have a
> somewhat rougher surface, but still not as rough as your tetrahedron.

Yes I know! :) The intention is not to portray a proper asteroid but a
fantastical representation. It is based on this image:

http://www.mcescher.com/Gallery/back-bmp/LW365.jpg

My goal was a 'realistic' terrestrial rock formation in a
situation that could never arise in (our) reality.

Bill


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid revisited
Date: 7 Feb 2008 09:10:03
Message: <web.47ab11276181678c731f01d10@news.povray.org>
"Thomas de Groot" <t.d### [at] internlDOTnet> wrote:
> Your experiment reminds me that I tried Jaap Frank's macro a couple of years
> ago, but without satisfying results.

It works well for small, low-detail surfaces, or, I guess, very smoothly varying
isosurfaces, but takes far too long to parse for proper detail. I guess its
chief use is for test renders, to sort out camera angles, object placement and
so on.


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From: nemesis
Subject: Re: Tetrahedral planetoid revisited
Date: 7 Feb 2008 09:20:00
Message: <web.47ab12be6181678ca9518f020@news.povray.org>
=?ISO-8859-1?Q?J=F6rg_=27Yadgar=27_Bleimann?= <yaz### [at] gmxde> wrote:
> Not very convincing - real asteroids

perhaps not much realist -- difficult to see that coming from a tetrahedron
planetoid -- but definitely impressive! :)


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From: Sven Littkowski
Subject: Re: Tetrahedral planetoid revisited
Date: 11 Feb 2008 13:22:33
Message: <47b09269$2@news.povray.org>
Use a plain white texture, and it could go perfectly as Guano!   :-)
Make an entire island out of it! Nyam!!!

Sven


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From: Sven Littkowski
Subject: Re: Tetrahedral planetoid revisited
Date: 11 Feb 2008 13:22:34
Message: <47b0926a@news.povray.org>
Besides that it could easily go as Guano, it is good as asteroid, too. Could 
you post the macro inside the Collectible Objects section?

Sven



"Bill Pragnell" <bil### [at] hotmailcom> schrieb im Newsbeitrag 
news:web.47a99724ffed9a2731f01d10@news.povray.org...
> Some of you may remember my Escher 'Double Planetoid' tribute from a 
> couple of
> years back. I've been playing with the rocky part of the planetoid, partly 
> to
> improve the realism of the rock and partly to make it render faster, 
> because
> I'm trying to render a large version to put on Zazzle (test renders at the
> final resolution were starting to take weeks. Damn you, radiosity +
> isosurface!)
>
> I got hold of Jaap Frank's tweaking of Kevin Loney's isosurface 
> approximation
> macro, see
>
>
http://news.povray.org/povray.binaries.images/thread/%3C3f012665%40news.povray.org%3E/
>
> for the original thread on this server. The tetrahedron below is built 
> from
> 2,400 copies of the demo scene's wrinkled sphere mesh at <100,100,100>
> resolution, and rendered in ~30 mins on my Macbook (peak memory ~22MB).
>
> The idea is to suggest a normal spherical planetoid but with mountainous 
> peaks
> that more naturally form a tetrahedron shape. I think it's a very nice 
> result
> so I thought I'd share it!
>
> Comments are of course welcome
>
> Bill
>


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid revisited
Date: 14 Feb 2008 06:40:00
Message: <web.47b427746181678c731f01d10@news.povray.org>
"Sven Littkowski" <sven [] jamaica-focus [] com> wrote:
> Besides that it could easily go as Guano, it is good as asteroid, too. Could
> you post the macro inside the Collectible Objects section?

By guano do you mean batsh*t? :-) I guess it does a little!

I'm still tinkering with it to minimise memory, maximise speed, the usual. I may
post it when I'm done.

Bill


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