Now that one does look good. 

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> 
> I does not look like it is an ideal cut. It seems like there is a "hole"
> in the culet of the diamond. This hole should not be there. 

My understanding is that the small facet at the 
bottom of the diamond is called the culet.

There seems to be many opinions about what is the 
best cut for a brilliant diamond.

I now think that I made the culet a little too big.

To make the culet facet smaller one would have to 
increase the 8.2 value a bit in the plane { -y, 8.2 }
statement in the Brilliant declaration.

To remove the culet facet, just delete this plane 
statement.

If the culet is made smaller or removed, then the 
-8.3 value in the bounded_by statement in should 
be lowered (more negative).


When I made this diamond shape, I spent much time 
searching the internet for information about the
geometry of diamonds.

I found most of the data I needed, but there were 
some data I could not find back then.

Therefore I'm not yet sure if all the facets are 
"right".


> See attached
> image. I played with photons and dispersionsettings until I was happy.
> 
> What do you think?

Thank you for rendering it with photons.

Now I'm sure that I like Photons very much !
I especially like the "fire" that appears
within the diamonds in your rendering.

I'm curious about how the code looks now.
Could you please post the code with your 
modifications for Photons ?

I read that Sigmund suggests placing the 
diamond closer to the floor to see the 
Photons.

Maybe it would then be wise to lower the 
reflection value for the blue "ground" 
plane so that the reflected diamond image 
does not destroy the caustics.


> Uhm, I'm not sure if I should tell you this, but my PIII 650 Mhz took 24
> minutes to render ed this image...

No, no, no, you shouldn't have told me that !


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Steve wrote:
> 
> I've started to render this, but can't get any photon effects.

Well, thanks for trying anyway.


> If someone could alter the code and add the photons and repost
> the code in p.b.sf or p.t.sf I'd be glad to render it.

I hope Sigmund will post his "Photon" modifications to my code.


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Sigmund Kyrre Aas wrote:

... snip 8< .... 

> Just noticed: this scene uses fade_power 1000; that is to turn on a new
> attenuation formula in MegaPov. Official Pov should use sub 2 fade_power.

I didn't know that. I was a little in doubt about that high number.
And I see now from the POV documentation that it was way to high for
an official POV-Ray rendering.

Thank you for clarifying.

... snip 8< .... 


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Tor Olav Kristensen wrote:
> 

> >
> > I does not look like it is an ideal cut. It seems like there is a "hole"
> > in the culet of the diamond. This hole should not be there.
> 
> My understanding is that the small facet at the
> bottom of the diamond is called the culet.

Yes, you're right. I didn't study the drawings and descriptions closely
enough.

> I now think that I made the culet a little too big.

I does look like it is a little bigger than it is supposed to be, yes.
Also, a brilliant cut diamond is supposed to have 58 facets, and not 74
facets as in your diamond?

> Thank you for rendering it with photons.

Your welcome, I've traced a new version with radiosity and a little
different settings.

> Now I'm sure that I like Photons very much !
> I especially like the "fire" that appears
> within the diamonds in your rendering.

The fire is caused by a dispersion setting of 0.75 in the interior
statement.

> I'm curious about how the code looks now.
> Could you please post the code with your
> modifications for Photons ?

But of course.

> Maybe it would then be wise to lower the
> reflection value for the blue "ground"
> plane so that the reflected diamond image
> does not destroy the caustics.

There are some caustics visible with the current settings. Have a look
at the attached image. 

-- 

------------------------------------------------------------------------
  +47 90 62 71 78          DoD#2101, DoDRT#017, NIC#015, PJ#006, OGM#007
  azo### [at] dodno, Ducati M600              Ubesudlet: Aldri eid en J&%#PS.

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Attachments:
Download 'crown_of_diamond_smooth_large.png' (146 KB)

Preview of image 'crown_of_diamond_smooth_large.png'

Sigmund Kyrre Aas wrote:
> 

> 
> > Uhm, I'm not sure if I should tell you this, but my PIII 650 Mhz took 24
> > minutes to render ed this image...
> 

> what causing the hole. I guess it should have a flat tip since Tor Olav
> obviously has done good research on this.

Yes, I was wrong, he is right ... the tip should be flat, but it is
exaggerated in the model.

> The dispersed light has a strange dirty look. 

I belive that the dirty looks comes from the pigment settings of the
diamond texture. I tried to set it to rgbf <1.0, 1.0, 1.0, 0.95> to see
if it improved things, but I will not know before another ... ohh, 20
hours or so. :-) If I bother to trace the image.

> I'm surprised of the speed. I made a triangle mesh for my diamond because I
> thought csg would be slow.

Well, the quality settings weren't that good. The last image I traced,
the one with radiosity, took about 22 hours.

-- 

------------------------------------------------------------------------
  +47 90 62 71 78          DoD#2101, DoDRT#017, NIC#015, PJ#006, OGM#007
  azo### [at] dodno, Ducati M600              Ubesudlet: Aldri eid en J&%#PS.

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Oh!  Wow!

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>
> I does look like it is a little bigger than it is supposed to be, yes.
> Also, a brilliant cut diamond is supposed to have 58 facets, and not 74
> facets as in your diamond?

In my shape there are 16 small facets that make 
up the girdle line.

I don't think that these usually are counted
in the total.

To get a diamond without these facets, then 
just remove these two lines from the Brilliant 
declaration in the source code:

MCircleSpread(plane { y, 0 rotate  -90*z }, 6.20, FacetSides, 1/4)
MCircleSpread(plane { y, 0 rotate  -90*z }, 6.20, FacetSides, 3/4)

(Also increase the 6.20 number in the bounded 
by statement.)


> > Thank you for rendering it with photons.
> 
> Your welcome, I've traced a new version with radiosity and a little
> different settings.

It looks less noisy now.

Thank you for this too.


> > Could you please post the code with your
> > modifications for Photons ?
> 
> But of course.

Thanks. 

I'm looking at it now trying to figure out what 
is happening.



Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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