POV-Ray : Newsgroups : povray.binaries.images : Fluorapophyllite-(K) Server Time
25 Jan 2022 02:48:10 EST (-0500)
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From: Thomas de Groot
Subject: Re: Fluorapophyllite-(K)
Date: 10 Nov 2021 02:13:52
Message: <618b7130@news.povray.org>
Op 06/11/2021 om 01:01 schreef Samuel B.:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Latest, less inclusions, and slightly more concentrated and de-centered.
> 
> It looks decent!
> 
> I've got a bunch of ideas, but I need to find the proper motivation to implement
> them :/
> 
> Only thing I want to suggest at this point is to maybe situate the light_source
> &/ sky_sphere so that it casts a highlight off either an outside or inside
> surface.
> 
> Sam
> 
Yes, I am fairly content. For now, I shall switch to other tasks and sit 
back. :-)

-- 
Thomas


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From: Samuel B 
Subject: Re: Fluorapophyllite-(K)
Date: 10 Nov 2021 17:10:00
Message: <web.618c42634f1e127bcb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 09/11/2021 om 20:02 schreef Kenneth:
> >
> > BTW, I did not realize that an object with ior could have inclusions (other
> > objects) with *different* ior's-- I thought such constructs would be an example
> > of 'variable' ior within an object, which cannot be accomplished in POV-ray,
> > AFAIU. I had a mistaken notion that the camera ray would 'see' the outer object
> > surface first, (...)
> >
> To tell the truth, I really do not know /how/ the different ior's are
> treated together. Afaik, this is not explained in the wiki pages. To
> keep on the safe side, I kept the inclusion's ior at 1.0 which is
> cheating of course, but at least I was not confronted to strange
> effects.

If I'm not mistaken, a ray evaluates all objects and their iors along its path
and changes its trajectory accordingly. So in a union, it is not really
'cheating' to have objects with an ior of 1 inside. They are treated as air
until the ray moves on. It's a reasonable alternative to using a difference
which - while not requiring objects with different iors - is very slow to trace.

Oh, and a while back, I found out that if you want to pretend that the camera is
inside some volume, say water, and you want to see air bubbles in that volume,
then for the air bubbles you would use the reciprocal of water's ior. So, the
bubbles would have an ior of 1/1.325, iinm.

Sam


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From: Alain Martel
Subject: Re: Fluorapophyllite-(K)
Date: 11 Nov 2021 11:44:14
Message: <618d485e@news.povray.org>
Le 2021-11-10 à 17:06, Samuel B. a écrit :
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Op 09/11/2021 om 20:02 schreef Kenneth:
>>>
>>> BTW, I did not realize that an object with ior could have inclusions (other
>>> objects) with *different* ior's-- I thought such constructs would be an example
>>> of 'variable' ior within an object, which cannot be accomplished in POV-ray,
>>> AFAIU. I had a mistaken notion that the camera ray would 'see' the outer object
>>> surface first, (...)
>>>
>> To tell the truth, I really do not know /how/ the different ior's are
>> treated together. Afaik, this is not explained in the wiki pages. To
>> keep on the safe side, I kept the inclusion's ior at 1.0 which is
>> cheating of course, but at least I was not confronted to strange
>> effects.
> 
> If I'm not mistaken, a ray evaluates all objects and their iors along its path
> and changes its trajectory accordingly. So in a union, it is not really
> 'cheating' to have objects with an ior of 1 inside. They are treated as air
> until the ray moves on. It's a reasonable alternative to using a difference
> which - while not requiring objects with different iors - is very slow to trace.
> 
> Oh, and a while back, I found out that if you want to pretend that the camera is
> inside some volume, say water, and you want to see air bubbles in that volume,
> then for the air bubbles you would use the reciprocal of water's ior. So, the
> bubbles would have an ior of 1/1.325, iinm.
> 
> Sam
> 

If you want to use a difference, then, you should use a blob instead of 
100' to 1000's of spheres.
That way, you benefit from the blob's hierarchy and internal bounding 
mechanism.


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From: Samuel B 
Subject: Re: Fluorapophyllite-(K)
Date: 11 Nov 2021 19:45:00
Message: <web.618db80f4f1e127bcb705ca46e741498@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:

> > (...) It's a reasonable alternative to using a difference
> > which - while not requiring objects with different iors - is very slow to trace.
>
> If you want to use a difference, then, you should use a blob instead of
> 100' to 1000's of spheres.
> That way, you benefit from the blob's hierarchy and internal bounding
> mechanism.

Blobs! I completely forgot about that option. And based on some experiments I
made once, I'd say you're probably right about the their higher rendering speed.

Yeah, I can see the benefit to using blobs to make air/fluid inclusions, and
then maybe applying a facets normal with metric 1 and maybe form <1, 0, 0>. This
way the clouds would refract/reflect light at certain angles only, thus giving a
more crystalline appearance. Hmm...

Sam


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From: Samuel B 
Subject: Re: Fluorapophyllite-(K)
Date: 12 Nov 2021 18:20:00
Message: <web.618ef5e64f1e127bcb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> "Samuel B." <stb### [at] hotmailcom> wrote:
> > Alain Martel <kua### [at] videotronca> wrote:
> >
> > > > (...) It's a reasonable alternative to using a difference
> > > > which - while not requiring objects with different iors - is very slow to
trace.
> > >
> > > If you want to use a difference, then, you should use a blob instead of
> > > 100' to 1000's of spheres.
> > > That way, you benefit from the blob's hierarchy and internal bounding
> > > mechanism.
> >
> > Blobs! I completely forgot about that option. (...)
>
> Blobs, of course! Completely forgot too. ;-)

Thomas, for some reason your message appeared in my inbox. But not from any real
e-mail address (the name was pretty obvious, but I thought I'd try to reply
anyway). So I suppose if the newsgroups ever go down for good, I'll meet you in
Valhalla! :P

But yeah, blobs seem like a worthy line of investigation :D

Sam


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From: Thomas de Groot
Subject: Re: Fluorapophyllite-(K)
Date: 13 Nov 2021 02:17:25
Message: <618f6685$1@news.povray.org>
Op 13/11/2021 om 00:16 schreef Samuel B.:
> Thomas, for some reason your message appeared in my inbox. But not from any real
> e-mail address (the name was pretty obvious, but I thought I'd try to reply
> anyway). So I suppose if the newsgroups ever go down for good, I'll meet you in
> Valhalla! :P
> 
Aargh! Did it again! :-(

Sorry Sam, I hit the wrong button in Thunderbird.

> But yeah, blobs seem like a worthy line of investigation :D
> 
> Sam
> 


-- 
Thomas


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From: Thomas de Groot
Subject: Re: Fluorapophyllite-(K)
Date: 15 Nov 2021 08:47:40
Message: <619264fc$1@news.povray.org>
Op 10-11-2021 om 08:11 schreef Thomas de Groot:

> To tell the truth, I really do not know /how/ the different ior's are 
> treated together. Afaik, this is not explained in the wiki pages. To 
> keep on the safe side, I kept the inclusion's ior at 1.0 which is 
> cheating of course, but at least I was not confronted to strange 
> effects. On my ToDo list I have put some ior experiments...
> 
Here it is. I replaced the cloud of inclusions by just one large blob 
inclusion with its own ior (salt water) and its own (coloured) 
absorption media. Indeed, there is no interaction between the different 
media colours (crystal and inclusion) or ior differences. Good to know! :-)

-- 
Thomas


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From: Thomas de Groot
Subject: Re: Fluorapophyllite-(K)
Date: 15 Nov 2021 10:36:02
Message: <61927e62$1@news.povray.org>
...And using a light probe in addition (with no_image).

-- 
Thomas


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From: Paolo Gibellini
Subject: Re: Fluorapophyllite-(K)
Date: 18 Nov 2021 05:28:11
Message: <61962abb$1@news.povray.org>
Il 15/11/2021 16:36, Thomas de Groot ha scritto:
 > ...And using a light probe in addition (with no_image).
 >

Bravo!

Paolo


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From: Thomas de Groot
Subject: Re: Fluorapophyllite-(K)
Date: 18 Nov 2021 07:28:27
Message: <619646eb$1@news.povray.org>
Op 18-11-2021 om 11:28 schreef Paolo Gibellini:
> Il 15/11/2021 16:36, Thomas de Groot ha scritto:
>  > ...And using a light probe in addition (with no_image).
>  >
> 
> Bravo!
> 
> Paolo

<grin>

-- 
Thomas


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