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From: Mike Miller
Subject: workbench_train_02.png
Date: 27 Nov 2023 18:00:00
Message: <web.65651eeecf034ce1896a9a9adabc9342@news.povray.org>
Updated train on workbench. Added Santa hat on mannequin, ribbon/bow on train,
and a few Christmas cards. Getting close on this one. May tweak the view angle a
bit.
Miller.


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workbench_train_02.png


 

From: Cousin Ricky
Subject: Re: workbench_train_02.png
Date: 29 Nov 2023 08:10:00
Message: <web.656736ea6e5f46b960e0cc3d949c357d@news.povray.org>
"Mike Miller" <mil### [at] gmailcom> wrote:
> Updated train on workbench. Added Santa hat on mannequin, ribbon/bow on train,
> and a few Christmas cards. Getting close on this one. May tweak the view angle a
> bit.
> Miller.

The textures of the metal trimmings on the locomotive look milky.  I suggest
lowering the diffuse and ambient values in the finish.


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From: Mike Miller
Subject: Re: workbench_train_02.png
Date: 29 Nov 2023 09:25:00
Message: <web.656748b26e5f46b9896a9a9adabc9342@news.povray.org>
"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> "Mike Miller" <mil### [at] gmailcom> wrote:
> > Updated train on workbench. Added Santa hat on mannequin, ribbon/bow on train,
> > and a few Christmas cards. Getting close on this one. May tweak the view angle a
> > bit.
> > Miller.
>
> The textures of the metal trimmings on the locomotive look milky.  I suggest
> lowering the diffuse and ambient values in the finish.

Thanks...I'll take a look at that.


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From: Alain Martel
Subject: Re: workbench_train_02.png
Date: 29 Nov 2023 10:04:36
Message: <65675304@news.povray.org>
Le 2023-11-29 à 09:20, Mike Miller a écrit :
> "Cousin Ricky" <rickysttATyahooDOTcom> wrote:
>> "Mike Miller" <mil### [at] gmailcom> wrote:
>>> Updated train on workbench. Added Santa hat on mannequin, ribbon/bow on train,
>>> and a few Christmas cards. Getting close on this one. May tweak the view angle a
>>> bit.
>>> Miller.
>>
>> The textures of the metal trimmings on the locomotive look milky.  I suggest
>> lowering the diffuse and ambient values in the finish.
> 
> Thanks...I'll take a look at that.
> Usually, a metallic finish should have an ambient of zero, or a very 
small value for a very dull surface.
Then, a diffuse should be less than 0.3. 0.3 for the dullest finish, 
down to zero for the very shiny.
Use reflection with the metallic attribute.
The finishes in metals.inc and golds.inc are totally wrong. They have 
insane ambient values. They where made to look good in an empty scene 
with nothing but black to reflect.


If the metal is to have a varnish coat, add a second mostly to fully 
transparent pigment layer above the metallic one. Add an interior 
statement for the IOR : interior{ ior 1.5 } And use the fresnel 
attribute : reflection{ 1 fresnel }.

That way, at high angle, you'll see almost only the metallic surface, 
but, at grazing angles, you get the fresnel reflection dominating.
Tried that and compared with actual metals, brass actually, coated with 
a varnish, and the result matched my physical samples.


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From: Mike Miller
Subject: Re: workbench_train_02.png
Date: 29 Nov 2023 12:15:00
Message: <web.656771366e5f46b9896a9a9adabc9342@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
> > "Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> >> "Mike Miller" <mil### [at] gmailcom> wrote:
> >>> Updated train on workbench. Added Santa hat on mannequin, ribbon/bow on train,
> >>> and a few Christmas cards. Getting close on this one. May tweak the view angle a
> >>> bit.
> >>> Miller.
> >>
> >> The textures of the metal trimmings on the locomotive look milky.  I suggest
> >> lowering the diffuse and ambient values in the finish.
> >
> > Thanks...I'll take a look at that.
> > Usually, a metallic finish should have an ambient of zero, or a very
> small value for a very dull surface.
> Then, a diffuse should be less than 0.3. 0.3 for the dullest finish,
> down to zero for the very shiny.
> Use reflection with the metallic attribute.
> The finishes in metals.inc and golds.inc are totally wrong. They have
> insane ambient values. They where made to look good in an empty scene
> with nothing but black to reflect.
>
>
> If the metal is to have a varnish coat, add a second mostly to fully
> transparent pigment layer above the metallic one. Add an interior
> statement for the IOR : interior{ ior 1.5 } And use the fresnel
> attribute : reflection{ 1 fresnel }.
>
> That way, at high angle, you'll see almost only the metallic surface,
> but, at grazing angles, you get the fresnel reflection dominating.
> Tried that and compared with actual metals, brass actually, coated with
> a varnish, and the result matched my physical samples.

Thanks for the info. The metal finishes I used have been tweaked from files long
ago. :) I'll review what I'm using and test out your suggestions. I'm sure I've
not tried adding a clear coat to basic metals.
Best regards,
Mike.


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From: Thomas de Groot
Subject: Re: workbench_train_02.png
Date: 7 Dec 2023 03:37:39
Message: <65718453@news.povray.org>
Op 29-11-2023 om 16:04 schreef Alain Martel:
> If the metal is to have a varnish coat, add a second mostly to fully 
> transparent pigment layer above the metallic one. Add an interior 
> statement for the IOR : interior{ ior 1.5 } And use the fresnel 
> attribute : reflection{ 1 fresnel }.
> 
> That way, at high angle, you'll see almost only the metallic surface, 
> but, at grazing angles, you get the fresnel reflection dominating.
> Tried that and compared with actual metals, brass actually, coated with 
> a varnish, and the result matched my physical samples.

I probably made a mistake somewhere, but I have a problem with this. The 
object looses its shadow in my code (see the egg in attached image).

This is the code used for the egg finish:

ovus { 1.00, 0.65
   pigment {rgb <0.4, 0.9, 0.4>}
   pigment {rgbt <0.9, 0.1, 0.1, 0.99>} //varnish coating!
   finish {
     metallic
     diffuse 0.0
     specular 0.80
     roughness 1/20
     reflection {0.90 fresnel metallic}
   }
   interior {ior 1.5}
   scale 0.5
   translate <0, 0.5, 0>
} // end of ovus --------------------------------------

specular / roughness can be left out without visible changes btw.

Thanks for any light on this!

-- 
Thomas


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Attachments:
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am_metallic finish.png


 

From: Thomas de Groot
Subject: Re: workbench_train_02.png
Date: 7 Dec 2023 03:42:35
Message: <6571857b@news.povray.org>
Op 7-12-2023 om 09:37 schreef Thomas de Groot:

> specular / roughness can be left out without visible changes btw.
> 
Not entirely true. Better leave those in place for the varnish (see image)

-- 
Thomas


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am_metallic finish.png


 

From: Cousin Ricky
Subject: Re: workbench_train_02.png
Date: 7 Dec 2023 08:20:00
Message: <web.6571c65b6e5f46b960e0cc3d949c357d@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 29-11-2023 om 16:04 schreef Alain Martel:
> > If the metal is to have a varnish coat, add a second mostly to fully
> > transparent pigment layer above the metallic one. Add an interior
> > statement for the IOR : interior{ ior 1.5 } And use the fresnel
> > attribute : reflection{ 1 fresnel }.
> >
> > That way, at high angle, you'll see almost only the metallic surface,
> > but, at grazing angles, you get the fresnel reflection dominating.
> > Tried that and compared with actual metals, brass actually, coated with
> > a varnish, and the result matched my physical samples.
>
> I probably made a mistake somewhere, but I have a problem with this. The
> object looses its shadow in my code (see the egg in attached image).
>
> This is the code used for the egg finish:
>
> ovus { 1.00, 0.65
>    pigment {rgb <0.4, 0.9, 0.4>}
>    pigment {rgbt <0.9, 0.1, 0.1, 0.99>} //varnish coating!
>    finish {
>      metallic
>      diffuse 0.0
>      specular 0.80
>      roughness 1/20
>      reflection {0.90 fresnel metallic}
>    }
>    interior {ior 1.5}
>    scale 0.5
>    translate <0, 0.5, 0>
> } // end of ovus --------------------------------------

Try it this way:

ovus { 1.00, 0.65
   texture {
      pigment {rgb <0.4, 0.9, 0.4>}
      finish {
         metallic
         diffuse 0.0
         ambient 0.0
         specular 0.80
         roughness 1/20
         reflection {0.90 metallic}
      }
   }
   texture {
      pigment {rgbt <0.9, 0.1, 0.1, 0.99>} //varnish coating!
      finish {
         reflection {0.90 fresnel}
      }
   }
   interior {ior 1.5}
   scale 0.5
   translate <0, 0.5, 0>
} // end of ovus --------------------------------------


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From: Thomas de Groot
Subject: Re: workbench_train_02.png
Date: 7 Dec 2023 08:50:56
Message: <6571cdc0@news.povray.org>
Op 7-12-2023 om 14:19 schreef Cousin Ricky:
> Try it this way:
> 
> ovus { 1.00, 0.65
>     texture {
>        pigment {rgb <0.4, 0.9, 0.4>}
>        finish {
>           metallic
>           diffuse 0.0
>           ambient 0.0
>           specular 0.80
>           roughness 1/20
>           reflection {0.90 metallic}
>        }
>     }
>     texture {
>        pigment {rgbt <0.9, 0.1, 0.1, 0.99>} //varnish coating!
>        finish {
>           reflection {0.90 fresnel}
>        }
>     }
>     interior {ior 1.5}
>     scale 0.5
>     translate <0, 0.5, 0>
> } // end of ovus --------------------------------------
> 
>
Aaa...! Of course. Thanks so much!

The coating is improved with specular, roughness and metallic added.

-- 
Thomas


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am_metallic finish.png


 

From: William F Pokorny
Subject: Re: workbench_train_02.png
Date: 10 Dec 2023 21:29:06
Message: <657673f2$1@news.povray.org>
On 12/7/23 03:37, Thomas de Groot wrote:
> ovus { 1.00, 0.65
>    pigment {rgb <0.4, 0.9, 0.4>}
>    pigment {rgbt <0.9, 0.1, 0.1, 0.99>} //varnish coating!

This syntax makes use of the shorthand 'texture-aspect' update method 
mentioned not too long ago as aside(1) here:

https://news.povray.org/povray.pov4.discussion.general/thread/%3C65518d6d%241%40news.povray.org%3E/

The first pigment{} updates the default texture's pigment, the second 
updates the modified texture again.

As also mentioned in that aside(1) in povray.pov4.discussion.general, 
when the interior_texture{} capability got added years ago this 
texture-aspect update method didn't get extended to the 
interior_teture{} too as should have been done. In other words, the 
shorthand update trick, ignores any defined interior_texture{} without a 
peep.

Well, on digging into the code recently with the idea of fixing that 
long-standing oversight in yuqk, I found there are additional criteria 
related to the type of pattern / special patterns in play too as to 
whether the short hand texture aspect updates work - even for texture{}.

So... I'm now toying with the idea of making all shorthand updates, 
parse errors in yuqk and suggesting this for v4.0 too. Essentially, yuqk 
would be forcing the texture{} block specification(s), always, as a path 
to consistent overall behavior.

This idea is easier for me to swallow because I tend to assign finish{}, 
normal{}, pigment{} (and interior{}) blocks to IDs before using them in 
texture{} or material{} blocks - also assigned to IDs - prior to use 
with objects. In other words, I already often code in this style. I do 
it because it makes modifications easier - but, it also avoids some of 
the subtle shifts / inconsistencies in parsing behavior which happen 
today with the texture shorthand / aspect update methods.

Aside: As an additional plus, forcing texture{} block(s) would enable 
eventual simplifications in the parsing code. This, rather than 
extending already complicated code to support interior_texture{} 
shorthand / aspect updates.

Thoughts / comments?

Bill P.


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