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Semi-inspired by my recent rendering, I'm creating a set of macros to
generate cut gems. Also, at one point waaaay back in the past, someone
made a post of diamonds modeled in a piece of software called GemCad. I
wanted to do something like that, but do it differently:
Pure CSG Diamonds.
So, Here are a couple cuts from a class of cuts called "Old European"
On the left is a Table Cut. Nothing exciting, basically follows the
natural shape of a diamond. On the right is an Old Single Cut with two
different parameters. Neither of these are the well-known brilliant cut,
though the Old Single cut may very well be the basis for the brilliant
cut, since it already has all of the proper angles.
There are 2 renders: One with a basic material so you can better see the
shape of the facets, and one with a diamond-like material, complete with
photons.
The next cuts I'll probably tackle are Eight cut, Emerald and Step cut--
since these are relatively simple. Eight cut may be a bit slightly
challenging because the facets are rounded at the edges, but I might be
wrong, it could be very simple, especially if the stone has a girdle.
I'm learning all sorts of terminology with this project:
The top "half" is the crown of the gem, the flat facet at the top is
called the table, the bottom "half" is the pavilion, and space between
the crown and pavilion is called the girdle, if it exists. At the bottom
of the pavilion there can be one more facet, called the cullet, or the
pavilion can come to a point.
I still need to work on cut depth, as well ( which determines the angles
in the pavilion )
Post a reply to this message
Attachments:
Download 'make_gemstone.jpg' (145 KB)
Download 'make_gemstone_basic.jpg' (152 KB)
Preview of image 'make_gemstone.jpg'
Preview of image 'make_gemstone_basic.jpg'
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Truly shiny. But such small pieces truly demand some focal blur to appear
realistic! Yes, I realize it may already have been hard enough with all the
refractions, caustics and dispersion... :P
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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.
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On Sat, 05 Sep 2009 23:50:21 -0400, Mike Raiford
<mraXXXiford.at.@g1023mail.com> wrote:
> On the left is a Table Cut. Nothing exciting, basically follows the
> natural shape of a diamond. On the right is an Old Single Cut with two
> different parameters. Neither of these are the well-known brilliant cut,
> though the Old Single cut may very well be the basis for the brilliant
> cut, since it already has all of the proper angles.
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.
--
<Insert witty .sig here>
Post a reply to this message
Attachments:
Download 'diamond0-lo.jpg' (5 KB)
Download 'diamond0-hi.jpg' (6 KB)
Download 'diamond-demo-c.png' (33 KB)
Download 'diamond_b90.png' (63 KB)
Download 'diamond_b75.png' (130 KB)
Preview of image 'diamond0-lo.jpg'
Preview of image 'diamond0-hi.jpg'
Preview of image 'diamond-demo-c.png'
Preview of image 'diamond_b90.png'
Preview of image 'diamond_b75.png'
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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.
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"Cousin Ricky" <ric### [at] yahoo com> 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.
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On Sun, 6 Sep 2009 09:20:38 +0100, "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.
It must be awe ;)
You are never anything but helpful except maybe knowledgeable :D
BTW that is a complement.
--
Regards
Stephen
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"Stephen" <mcavoysAT@aolDOTcom> wrote in message
news:mav6a59adkgch33h2jpnd0gmgsq4stjhpf@4ax.com...
> On Sun, 6 Sep 2009 09:20:38 +0100, "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.
>
> It must be awe ;)
> You are never anything but helpful except maybe knowledgeable :D
> BTW that is a complement.
> --
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.
Don't you just hate those tricky situations :o)
Regards,
Chris B.
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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.
Post a reply to this message
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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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"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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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 ;)
Post a reply to this message
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Cousin Ricky wrote:
> I was alluing to your enthusiam over the Objet Collection. No offense was
> intended.
Oooh ... Nice! :D
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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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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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Cousin Ricky a écrit :
> 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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Eight cut, under an HDR probe, with traditional lighting for photo
effects...
Post a reply to this message
Attachments:
Download 'make_gemstone.jpg' (152 KB)
Preview of image 'make_gemstone.jpg'
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Mike Raiford a écrit :
> 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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