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31 Jul 2024 18:17:48 EDT (-0400)
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From: Mike Raiford
Subject: Re: Shiny things!
Date: 6 Sep 2009 08:37:29
Message: <4aa3ad09$1@news.povray.org>
Cousin Ricky wrote:
> What's your max_trace_level?  I find that I need an insanely high value high
> value for this sort of thing--at least 60 to 100 to get rid of the visibly dark
> areas.  Sometimes tracing doesn't bail even after 256, although at this point it
> doesn't make much visual impact.
> 

50 but yeah... it went all the way to 50. I'm trying it with 255 to see 
if there's a difference.


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From: Mike Raiford
Subject: Re: Shiny things!
Date: 6 Sep 2009 08:37:52
Message: <4aa3ad20$1@news.povray.org>
Cousin Ricky wrote:
> What's your max_trace_level?  I find that I need an insanely high value high
> value for this sort of thing--at least 60 to 100 to get rid of the visibly dark
> areas.  Sometimes tracing doesn't bail even after 256, although at this point it
> doesn't make much visual impact.
> 

Oh, and I think some of it may be the black "sky" that it's refracting...


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From: Cousin Ricky
Subject: Re: Shiny things!
Date: 6 Sep 2009 08:40:00
Message: <web.4aa3ad5d1f77a85f78641e0c0@news.povray.org>
"Chris B" <nom### [at] nomailcom> wrote:
> "Cousin Ricky" <ric### [at] yahoocom> wrote in message
> news:op.### [at] your-727a0a4e7cvipowernetnet...
> >
> > I know Chris B. will show up to buttonhole us any second now
>
> I think you may be confusing me with someone else, but if it really is me
> you're targetting with this comment I'd appreciate an explanation. I don't
> think that I've done anything to offend you (or hopefully anyone else for
> that matter). If there is something you would prefer to discuss privately,
> feel free to drop me a line at Chris.Bartlett2 on the server virgin.net.
>
> Chris B.

I was alluing to your enthusiam over the Objet Collection.  No offense was
intended.


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From: Mike Raiford
Subject: Re: Shiny things!
Date: 6 Sep 2009 08:43:37
Message: <4aa3ae79$1@news.povray.org>
Sabrina Kilian wrote:
> Very sparkly!
> Are you working towards just certain cuts, or any arbitrary stone
> cutting instruction set? I stopped pursuing an instruction parser, but
> seeing these pictures I will have to start again.

As many cuts as I can find, but with adjustable parameters. A general 
parser would be way too much, I think.

The idea is for the user to say "I want an emerald cut, with a w/h ratio 
of 1:1.4 a table height of 25% with a pavilion depth of 60% and no cullet."

Well, it would really be something like Gemstone_EmeralCut(1.4,.25,.6,0) 
But, you get the picture ;)


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From: Mike Raiford
Subject: Re: Shiny things!
Date: 6 Sep 2009 08:53:14
Message: <4aa3b0ba$1@news.povray.org>
Cousin Ricky wrote:

> I was alluing to your enthusiam over the Objet Collection.  No offense was
> intended.

Oooh ... Nice! :D


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From: Stephen
Subject: Re: Shiny things!
Date: 6 Sep 2009 10:12:54
Message: <hig7a51ahubmnld5ql7k13bmk4df3knkp0@4ax.com>
On Sun, 6 Sep 2009 12:13:12 +0100, "Chris B" <nom### [at] nomailcom> wrote:

>Thanks Stephen,
>
>TBH I wasn't sure what "to buttonhole" meant when I first saw it. The trusty 
>Internet delivered the definition of "to detain (a person) in conversation 
>against their will" which left me feeling a little offended, but also 
>between a rock and a hard place. I wouldn't want such an accusation to go 
>unchallenged, but pursuing the matter will almost certainly  make me guilty 
>of engaging someone in a conversation they probably don't want to have. 

It can be a bit of a minefield communicating when you're not face to face, with
people you only know from the internet.
True buttonhole does mean "to detain (a person) in conversation against their
will" but it is often said "tongue in cheek" :)
At least our Cuz didn't say that you could bore for England :P <- Joke
I have noticed that over the years you have spent a lot of time helping people
on these newsgroups. It is appreciated. 

>Don't you just hate those tricky situations :o)

Nope! :P
Just get stuck in there. One with the heid and one with the bunnet </Joke>

Actually life is too short to spend time worrying and brooding. You did the
right thing asking. As did Rick in keeping his reply short. 
There is enough argument about gamma never mind anything else :)
-- 

Regards
     Stephen


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From: nemesis
Subject: Re: Shiny things!
Date: 6 Sep 2009 11:10:00
Message: <web.4aa3cfa21f77a85f8196c560@news.povray.org>
Mike Raiford <mraXXXiford.at.@g1023mail.com> wrote:
> Cousin Ricky wrote:
> > What's your max_trace_level?  I find that I need an insanely high value high
> > value for this sort of thing--at least 60 to 100 to get rid of the visibly dark
> > areas.  Sometimes tracing doesn't bail even after 256, although at this point it
> > doesn't make much visual impact.
> >
>
> 50 but yeah... it went all the way to 50. I'm trying it with 255 to see
> if there's a difference.

BTW, don't forget about the "precious" keyword adc_bailout.  Helps a lot with
too much refraction.  An Alain tip I never forget... :)


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From: Alain
Subject: Re: Shiny things!
Date: 6 Sep 2009 12:51:49
Message: <4aa3e8a5$1@news.povray.org>


> I did a brilliant round cut a few years ago, but was never satisfied 
> with the results.  They just never had the level of sparkle that I see 
> in real diamonds.  Looking at the light traces, I suspect that my 
> parameters may be suboptimal.  (I got the parameters from a Web site 
> that appears to have passed on.)
> 
> I also suspect a bug (feature?) in dispersion: renders seem to be darker 
> than without dispersion.  It just occurred to me that the multiple 
> reflections and refractions in a cut gem could possibly exacerbate the 
> problem.
> 
> I know Chris B. will show up to buttonhole us any second now, so I'll 
> just say that I've been shy about submitting this, because of my 
> dissatisfaction of the sparkle, but also because I fear that, with just 
> the one cut, the module lacks generality.
> 
> 

Just a few remarks:
You may need a stronger dispersion, and probably more dispersion_samples.
Your specular highlights look like they are not sharp enough.
If using phong, try to multiply phong_size by around 100.
If using specular, try dividing roughness by around 100.
If you use a look_like for your light_source, try yo mage it smaller, or 
put the light farther away.

Your transmit or filter value may be set to low, make it much closer to 
1. Filter + transmit should add to 1 or almost 1.

Add some variable reflection and don't forget fresnel and conserve_energy.

When you add dispersion, the intensity get spread out. So, it's only 
normal that the result looks darker. A solution is to mage the 
light_source slightly stronger.

Adding photons can also add a great deal in realism.


Alain


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From: Mike Raiford
Subject: Re: Shiny things!
Date: 6 Sep 2009 23:17:14
Message: <4aa47b3a@news.povray.org>
Eight cut, under an HDR probe, with traditional lighting for photo 
effects...


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Attachments:
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make_gemstone.jpg


 

From: Alain
Subject: Re: Shiny things!
Date: 7 Sep 2009 14:25:10
Message: <4aa55006$1@news.povray.org>

> Eight cut, under an HDR probe, with traditional lighting for photo 
> effects...
> 
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
Much beter. Obviously, the black areas where reflections of the black 
background.


Alain


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