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From: Andrew C on Mozilla
Subject: Not a little gem... (~50KB)
Date: 9 May 2004 05:57:24
Message: <409e0084@news.povray.org>
Hi folks.

This is supposed to be a an extreme closeup of a small gemstone (a few 
mm across), set in a gold setting. But it looks nothing like that - and 
I can't figure out why.

The stone doesn't look remotely gem-like. Can't figure that out. It's 
transparent, reflective, and reflective. What am I missing?

The setting doesn't look like gold. I've fiddled with brilliance, 
specular, roughness, reflection, and turned on metallic (as well as 
conserve_energy). Still doesn't look remotely like metal. Why?

Also can't figure out why the metal setting apparently isn't resulting 
in any photons. (It makes the photon process hundreds of times slower - 
that is, I had to multiply the photon spacing a few hundred times to get 
it to render this year.)

This was supposed to end up being a single link in a bracelet - but it 
looks so rubbish I hadn't get that far yet.

Any ideas?
Andrew @ home.


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From: St 
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 07:45:23
Message: <409e19d3@news.povray.org>
"Andrew C on Mozilla" <voi### [at] devnull> wrote in message
news:409e0084@news.povray.org...
> Hi folks.
>
> This is supposed to be a an extreme closeup of a small gemstone (a
few
> mm across), set in a gold setting. But it looks nothing like that -
and
> I can't figure out why.
> The stone doesn't look remotely gem-like. Can't figure that out.
It's
> transparent, reflective, and reflective. What am I missing?


Your gemstone needs facets on the back of the stone. Do a Google
search for 'Baguette Cut', 'Emerald Cut', and 'Princess Cut'. You'll
see that your gemstone also needs to be shallower.


> The setting doesn't look like gold. I've fiddled with brilliance,
> specular, roughness, reflection, and turned on metallic (as well as
> conserve_energy). Still doesn't look remotely like metal. Why?

    It looks like gold to me - it's not that bad, try turning the
ambient and reflection up a touch. The tips of your 'prongs' need to
be bent over the stone too.


>
> Also can't figure out why the metal setting apparently isn't
resulting
> in any photons. (It makes the photon process hundreds of times
slower -
> that is, I had to multiply the photon spacing a few hundred times to
get
> it to render this year.)

      No idea.

>
> This was supposed to end up being a single link in a bracelet - but
it
> looks so rubbish I hadn't get that far yet.

   Perseverance!  ;)

    ~Steve~


>
> Any ideas?
> Andrew @ home.
>
>


----------------------------------------------------------------------
----------


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From: Andrew C on Mozilla
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 08:40:19
Message: <409e26b3$1@news.povray.org>
>>This is supposed to be a an extreme closeup of a small gemstone (a
>>few mm across), set in a gold setting. But it looks nothing like
 >>that - and I can't figure out why.
 >>
>>The stone doesn't look remotely gem-like. Can't figure that out.
>>It's transparent, reflective, and reflective. What am I missing?
> 
> Your gemstone needs facets on the back of the stone. Do a Google
> search for 'Baguette Cut', 'Emerald Cut', and 'Princess Cut'. You'll
> see that your gemstone also needs to be shallower.

...so what you're saying is that it's all in the cut?

OK... well just Googling for (e.g.) Emerald Cut gives me a huge list of 
shops that will *sell* me an emerald cut gemstone of one sort or 
another... I've found a few little black and white 2D outline drawings 
and a few photos, but I can't find anything clear enough to make a 
POV-Ray model from.

Anyone know where I can find technical drawings with measurements?

>>The setting doesn't look like gold. I've fiddled with brilliance,
>>specular, roughness, reflection, and turned on metallic (as well as
>>conserve_energy). Still doesn't look remotely like metal. Why?
> 
> 
>     It looks like gold to me - it's not that bad, try turning the
> ambient and reflection up a touch. The tips of your 'prongs' need to
> be bent over the stone too.

I don't know... maybe the lighting is wrong... I already have 3 light 
sources, and still can't get it to look right. Oh yes, and I know about 
the prongs - but I have no idea how to explain that to POV-Ray.

>    Perseverance!  ;)

Well, this *is* the POV-Ray NG isn't it? ;-) LOL!

Andrew @ home.


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From: Matt Burns
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 09:15:33
Message: <409e2ef5$1@news.povray.org>
Hi!

> Anyone know where I can find technical drawings with measurements?

Try his link http://www.3dlapidary.com/Home.htm it could of help. They got a
lot of free *.dxf models of gemsone cuts.


Matt


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From: Arthur Flint
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 09:39:09
Message: <409e347d@news.povray.org>
Matt Burns wrote:
> Hi!
> 
> 
>>Anyone know where I can find technical drawings with measurements?
> 
> 
> Try his link http://www.3dlapidary.com/Home.htm it could of help. They got a
> lot of free *.dxf models of gemsone cuts.
> 
> 
> Matt
> 
> 
Thanks for the link. My 25'th is comming up soon and there is just no 
way I can afford a real gemstone, so--- POV to the rescue!
(it is a lot better than the silver dime-in-ring joke. I took a 1958 
silver US dime and placed it inside my wedding band. She laughed, a little.)


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From: Steven Pigeon
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 09:40:27
Message: <409e34cb$1@news.povray.org>
I think it needs a bit of dispersion (1.1, 50 samples)
and maybe a normal ( something like bump 0.1 scale 100 )
so that it warps very gently the surface of the stone.

This should produce interesing highlights.

Best,

    S.

--
Steven Pigeon, Ph. D.
ste### [at] stevenpigeoncom
ste### [at] videotronca
"Andrew C on Mozilla" <voi### [at] devnull> wrote in message
news:409e0084@news.povray.org...
> Hi folks.
>
> This is supposed to be a an extreme closeup of a small gemstone (a few
> mm across), set in a gold setting. But it looks nothing like that - and
> I can't figure out why.
>
> The stone doesn't look remotely gem-like. Can't figure that out. It's
> transparent, reflective, and reflective. What am I missing?
>
> The setting doesn't look like gold. I've fiddled with brilliance,
> specular, roughness, reflection, and turned on metallic (as well as
> conserve_energy). Still doesn't look remotely like metal. Why?
>
> Also can't figure out why the metal setting apparently isn't resulting
> in any photons. (It makes the photon process hundreds of times slower -
> that is, I had to multiply the photon spacing a few hundred times to get
> it to render this year.)
>
> This was supposed to end up being a single link in a bracelet - but it
> looks so rubbish I hadn't get that far yet.
>
> Any ideas?
> Andrew @ home.
>
>


----------------------------------------------------------------------------
----


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From: Andrew C on Mozilla
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 09:55:58
Message: <409e386e$1@news.povray.org>
>>Anyone know where I can find technical drawings with measurements?
> 
> Try his link http://www.3dlapidary.com/Home.htm it could of help. They got a
> lot of free *.dxf models of gemsone cuts.

Yes - I already found this by Googling.

Trouble is... what the hell is a DXF file??

Andrew @ home.


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From: Andrew C on Mozilla
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 10:27:36
Message: <409e3fd8$1@news.povray.org>
> Thanks for the link. My 25'th is comming up soon and there is just no 
> way I can afford a real gemstone, so--- POV to the rescue!
> (it is a lot better than the silver dime-in-ring joke. I took a 1958 
> silver US dime and placed it inside my wedding band. She laughed, a 
> little.)

...and why do you think *I* was trying to make a ruby bracelet? ;-)


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From: St 
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 10:37:30
Message: <409e422a@news.povray.org>
"Andrew C on Mozilla" <voi### [at] devnull> wrote in message
news:409e26b3$1@news.povray.org...
> >>This is supposed to be a an extreme closeup of a small gemstone (a
> >>few mm across), set in a gold setting. But it looks nothing like
>  >>that - and I can't figure out why.
>  >>
> >>The stone doesn't look remotely gem-like. Can't figure that out.
> >>It's transparent, reflective, and reflective. What am I missing?
> >
> > Your gemstone needs facets on the back of the stone. Do a Google
> > search for 'Baguette Cut', 'Emerald Cut', and 'Princess Cut'.
You'll
> > see that your gemstone also needs to be shallower.
>
> ...so what you're saying is that it's all in the cut?

   Yes, normally. A diamond is the perfect example of refraction. I
forgot to say that you need more facets on the crown, (top, table), of
your gemstone too - depending on what cut you want.


>
> OK... well just Googling for (e.g.) Emerald Cut gives me a huge list
of
> shops that will *sell* me an emerald cut gemstone of one sort or
> another... I've found a few little black and white 2D outline
drawings
> and a few photos, but I can't find anything clear enough to make a
> POV-Ray model from.

     Hit 'Images' in Google for all of those terms...


>
> Anyone know where I can find technical drawings with measurements?
>
> >>The setting doesn't look like gold. I've fiddled with brilliance,
> >>specular, roughness, reflection, and turned on metallic (as well
as
> >>conserve_energy). Still doesn't look remotely like metal. Why?
> >
> >
> >     It looks like gold to me - it's not that bad, try turning the
> > ambient and reflection up a touch. The tips of your 'prongs' need
to
> > be bent over the stone too.
>
> I don't know... maybe the lighting is wrong... I already have 3
light
> sources, and still can't get it to look right.

   Well, with this reflective surface, you need the gold to reflect
*something*, so, put something behind the camera, put something above
the setting.

  Also, try this for a gold texture:

   texture {T_Gold_1A }

    finish {
        ambient 0.035
        diffuse .3
        brilliance 5
        phong 0.41
        phong_size 2}}



 Oh yes, and I know about
> the prongs - but I have no idea how to explain that to POV-Ray.

   I'm sure someone can tell you, but I don't know either!  :o/

>
> >    Perseverance!  ;)
>
> Well, this *is* the POV-Ray NG isn't it? ;-) LOL!

   It is??!  Sheesh! I've been coming to the wrong place all these
years!  :-O


   ~Steve~  ;)



>
> Andrew @ home.


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From: Alain
Subject: Re: Not a little gem... (~50KB)
Date: 9 May 2004 11:36:01
Message: <409e4fe1$1@news.povray.org>
Andrew C on Mozilla nous apporta ses lumieres ainsi en ce 2004/05/09 
05:54... :

> Hi folks.
>
> This is supposed to be a an extreme closeup of a small gemstone (a few 
> mm across), set in a gold setting. But it looks nothing like that - 
> and I can't figure out why.
>
> The stone doesn't look remotely gem-like. Can't figure that out. It's 
> transparent, reflective, and reflective. What am I missing?
>
> The setting doesn't look like gold. I've fiddled with brilliance, 
> specular, roughness, reflection, and turned on metallic (as well as 
> conserve_energy). Still doesn't look remotely like metal. Why?
>
> Also can't figure out why the metal setting apparently isn't resulting 
> in any photons. (It makes the photon process hundreds of times slower 
> - that is, I had to multiply the photon spacing a few hundred times to 
> get it to render this year.)
>
> This was supposed to end up being a single link in a bracelet - but it 
> looks so rubbish I hadn't get that far yet.
>
> Any ideas?
> Andrew @ home.
>
>
> ------------------------------------------------------------------------
>
The IOR for your gem may be to low, ruby's ior is higher than glass, 
close to 2 I think. Did you set the fade_distance and fade_power? Do you 
use media_atenuation? Sould be on. Now, it look like only the surfaces 
have any colour.
This look like a midle-ages kind of cut, no faceting on the under side, 
very box like (the had still to develop the needed skils and tools).
Did you set the metal as a target for the photons?
It may be "good enough" as is if it's going to be small in the final 
scene. How many links in your bracelet? How large will be the complete 
bracelet in your scene? You may do a trial render of the complete 
bracelet at the planed scale (no protons, no radiosity, no aa, only 1 or 
2 light).

Alain


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