"Kenneth" <kdw### [at] gmailcom> wrote:
> 3rd glass from the right. I like it's shape and sort-of translucent quality, not
> quite crystal-clear.

 That was my original choice too, before I looked at anyone else's.

 Looking at them more, I think the left most of either shape.  At least a dark
liquid Lowes might bring out the muted reflections,  and bright things either
refracted or seen transparently through them might show about right.

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On 2017-04-02 01:09 PM (-4), Le_Forgeron wrote:
> More important, which glass would you pick ?

I like the leftmost.

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On 2-4-2017 19:09, Le_Forgeron wrote:
> WIP
>
> I need to find some beverage for the glasses.
>
> I also need to define the suitable level of it.
>
> More important, which glass would you pick ?
>

They are all pretty good. By instinct, I would pick third from left with 
2/3 full of Bourgogne (aligoté if you want).

-- 
Thomas

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"omniverse" <omn### [at] charternet> wrote:
> "Kenneth" <kdw### [at] gmailcom> wrote:
> > 3rd glass from the right. I like it's shape and sort-of translucent quality, not
> > quite crystal-clear.
>
>  That was my original choice too, before I looked at anyone else's.
>
>  Looking at them more, I think the left most of either shape.  At least a dark
> liquid Lowes might bring out the muted reflections,  and bright things either
> refracted or seen transparently through them might show about right.

Note to self: carefully read the text on smartphone when using talk instead of
type. Lowes is a home/hardware store in case anyone out there is wondering what
beverage I might have been saying, others of you might have guessed the mistake.

Seeing the image a 3rd time my eyes were drawn to that 3rd from right glass
again, and the 3rd from left. Both look very much the same too, aside from
shape. So maybe I should have stayed with my 1st choice. ;)

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Am 02.04.2017 um 19:09 schrieb Le_Forgeron:

> More important, which glass would you pick ?

To be frank, I don't find any of them particularly convincing. Most of
them seem to "swallow" light, while the 2nd from the left of each batch
seem to "emit" light.

For genuinely convincing glass material, I think it is essential...

- to control any desired tint via distance-based attenuation (`fade_*`
in interior block) rather than pigment (i.e. use `rgbt 1.0` as pigment)

- to control the balance between reflection and transmission via the
fresnel mechanism (realistic `ior` in interior block; `reflection { 1.0
fresnel on } conserve_energy` in the finish block)

It may also help to control the brightness of highlights via physical
parameters rather than tweaking (i.e. use `specular albedo 1.0` and
`fresnel on` directly in the finish block).


Of course it is also essential to provide a good environment to reflect,
and maybe the "not particularly convincing" impression I get might just
be due to the simple checker pattern. I'm not sure about that one.

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On 2017-04-03 08:41 AM (-4), clipka wrote:
> For genuinely convincing glass material, I think it is essential...
>
> - to control any desired tint via distance-based attenuation (`fade_*`
> in interior block) rather than pigment (i.e. use `rgbt 1.0` as pigment)
>
> - to control the balance between reflection and transmission via the
> fresnel mechanism (realistic `ior` in interior block; `reflection { 1.0
> fresnel on } conserve_energy` in the finish block)
>
> It may also help to control the brightness of highlights via physical
> parameters rather than tweaking (i.e. use `specular albedo 1.0` and
> `fresnel on` directly in the finish block).

The question I have is how to best simulate interface between the glass 
and a liquid without incurring either a coincident surface or spurious 
IOR changes due to non-coincident surfaces.

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Cousin Ricky <ric### [at] yahoocom> wrote:

> The question I have is how to best simulate interface between the glass
> and a liquid without incurring either a coincident surface or spurious
> IOR changes due to non-coincident surfaces.
The way it used to be done was to overlap the surfaces to prevent an air gap
from being in there.

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> Cousin Ricky <ric### [at] yahoocom> wrote:
>
>> The question I have is how to best simulate interface between the glass
>> and a liquid without incurring either a coincident surface or spurious
>> IOR changes due to non-coincident surfaces.
> The way it used to be done was to overlap the surfaces to prevent an air gap
> from being in there.
>
>

The best way is to clip the glass, have an open to the top object for 
the glass-liquid part with the differential ior for the interface and a 
third object for the top surface, all enclosed into an union.
The glass part have the glass' ior. Maybe 1.5 to 1.8
The top surface have the ior of the liquid, around 1.33.
The inner surface ior would be ior (ior_glass/ior_liquid) -> 1.1278 to 
1.353.

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Le 05/04/2017 à 02:41, Alain a écrit :
> Le 17-04-04 à 19:38, omniverse a écrit :
>> Cousin Ricky <ric### [at] yahoocom> wrote:
>>
>>> The question I have is how to best simulate interface between the glass
>>> and a liquid without incurring either a coincident surface or spurious
>>> IOR changes due to non-coincident surfaces.
>> The way it used to be done was to overlap the surfaces to prevent an
>> air gap
>> from being in there.
>>
>>
>
> The best way is to clip the glass, have an open to the top object for
> the glass-liquid part with the differential ior for the interface and a
> third object for the top surface, all enclosed into an union.
> The glass part have the glass' ior. Maybe 1.5 to 1.8
> The top surface have the ior of the liquid, around 1.33.
> The inner surface ior would be ior (ior_glass/ior_liquid) -> 1.1278 to
> 1.353.

Or you could just go that way:

http://wiki.povray.org/content/User:Le_Forgeron/HowTo/Perfect_glass

No overlapping, and just CSG in the right order.

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Am 05.04.2017 um 13:05 schrieb Le_Forgeron:

> http://wiki.povray.org/content/User:Le_Forgeron/HowTo/Perfect_glass
> 
> No overlapping, and just CSG in the right order.

You deserve a cigar!

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