OK, um, I just had this idea for the POV-Team... and just for everyone else
to have a think about...

How about adding translucency to textures in POV-Ray?  Now would that be a
cool idea or what?  ;-)

Then you could make REAL looking candles and stuff...   Anyway, just an
idea...

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

P.S.  Or maybe even add fluorescence too... That would also be extremely
cool :)

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I would definitely like the translucency, but how would the flourescence be
used? Ambient can be used to simulate it to some extent. I have attempted to
use transmit to simulate translucency, but that didn't work well, the
background showed through. I think the best solution to that problem, short of
adding a new feature, would be a media, but I am not very good at media yet.

Lance Birch wrote:

> OK, um, I just had this idea for the POV-Team... and just for everyone else
> to have a think about...
>
> How about adding translucency to textures in POV-Ray?  Now would that be a
> cool idea or what?  ;-)
>
> Then you could make REAL looking candles and stuff...   Anyway, just an
> idea...
>
> --
> Lance.
>
> ---
> For the latest 3D Studio MAX plug-ins, images and much more, go to:
> The Zone - http://come.to/the.zone
>
> P.S.  Or maybe even add fluorescence too... That would also be extremely
> cool :)

Post a reply to this message

Hi Lance!

Could you please, to a non-native English speaker, explain what you mean
with "translucency" in this context? I understand the word in general, but I
fail to catch where it would be different than the current filter/transmit
combination.

Thanks,

Johannes.

Lance Birch wrote in message <370f4c31.0@news.povray.org>...
>OK, um, I just had this idea for the POV-Team... and just for everyone else
>to have a think about...
>
>How about adding translucency to textures in POV-Ray?  Now would that be a
>cool idea or what?  ;-)
>
>Then you could make REAL looking candles and stuff...   Anyway, just an
>idea...
>
>--
>Lance.
>
>
>---
>For the latest 3D Studio MAX plug-ins, images and much more, go to:
>The Zone - http://come.to/the.zone
>
>P.S.  Or maybe even add fluorescence too... That would also be extremely
>cool :)
>
>

Post a reply to this message

I believe he means diffuse transmittance, like a sheet of paper or matte
plastic/glass. Also, I believe something like this is considered for 3.5 in
the form of allowing double_illuminate as a keyword.
PS. double_illuminate means that both sides of the object get illuminated by
the light source and shadowed by an object. It's not a precise
representation of translucency, but it does the job in most cases.

Margus

Johannes Hubert wrote in message <370f67a4.0@news.povray.org>...
>Hi Lance!
>
>Could you please, to a non-native English speaker, explain what you mean
>with "translucency" in this context? I understand the word in general, but
I
>fail to catch where it would be different than the current filter/transmit
>combination.
>
>Thanks,
>
>Johannes.
>
>Lance Birch wrote in message <370f4c31.0@news.povray.org>...
>>OK, um, I just had this idea for the POV-Team... and just for everyone
else
>>to have a think about...
>>
>>How about adding translucency to textures in POV-Ray?  Now would that be a
>>cool idea or what?  ;-)
>>
>>Then you could make REAL looking candles and stuff...   Anyway, just an
>>idea...
>>
>>--
>>Lance.
>>
>>
>>---
>>For the latest 3D Studio MAX plug-ins, images and much more, go to:
>>The Zone - http://come.to/the.zone
>>
>>P.S.  Or maybe even add fluorescence too... That would also be extremely
>>cool :)
>>
>>
>
>

Post a reply to this message

That might be okay. Thing is, if filter (and/or transmit) is used in
conjunction with fade_distance and fade_power the effect could be
achieved now I believe, along with the right texture. The fluorescence
would be particularly interesting. The POVAFX custom compile used
similar for lights. Objects having this effect would be fantastic.
Radiosity and media working together might do this now, I haven't tried
it.


Margus Ramst wrote:
> 
> I believe he means diffuse transmittance, like a sheet of paper or matte
> plastic/glass. Also, I believe something like this is considered for 3.5 in
> the form of allowing double_illuminate as a keyword.
> PS. double_illuminate means that both sides of the object get illuminated by
> the light source and shadowed by an object. It's not a precise
> representation of translucency, but it does the job in most cases.
> 
> Margus
> 
> Johannes Hubert wrote in message <370f67a4.0@news.povray.org>...
> >Hi Lance!
> >
> >Could you please, to a non-native English speaker, explain what you mean
> >with "translucency" in this context? I understand the word in general, but
> I
> >fail to catch where it would be different than the current filter/transmit
> >combination.
> >
> >Thanks,
> >
> >Johannes.
> >
> >Lance Birch wrote in message <370f4c31.0@news.povray.org>...
> >>OK, um, I just had this idea for the POV-Team... and just for everyone
> else
> >>to have a think about...
> >>
> >>How about adding translucency to textures in POV-Ray?  Now would that be a
> >>cool idea or what?  ;-)
> >>
> >>Then you could make REAL looking candles and stuff...   Anyway, just an
> >>idea...
> >>
> >>--
> >>Lance.
> >>
> >>
> >>---
> >>For the latest 3D Studio MAX plug-ins, images and much more, go to:
> >>The Zone - http://come.to/the.zone
> >>
> >>P.S.  Or maybe even add fluorescence too... That would also be extremely
> >>cool :)
> >>
> >>
> >
> >

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto:inv### [at] aolcom?Subject=PoV-News

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Until you prove me wrong (preferably with an image/scene) I remain
sceptical. AFAIK, POV's transmit and filter are fundamentally different from
translucency. They do not diffuse (scatter) incoming light. Ligh fading
would simply make the object darker (i.e. allow less ligh to pass through).

Correct rendering of translucency is already possible (more realistically
than with double_illuminate) - with the use of media. I've tested this quite
extensively and the results are good. Perhaps I'll post an example to p.b.i
in the near future.

Margus

Bob Hughes wrote in message <370FC5F1.27582B0E@aol.com>...
>That might be okay. Thing is, if filter (and/or transmit) is used in
>conjunction with fade_distance and fade_power the effect could be
>achieved now I believe, along with the right texture. The fluorescence
>would be particularly interesting. The POVAFX custom compile used
>similar for lights. Objects having this effect would be fantastic.
>Radiosity and media working together might do this now, I haven't tried
>it.
>

Post a reply to this message

Flourescene is quite different to ambient lighting... the main thing is the
way the object reacts to light.  For example you'd need some kind of
flourescene bias so that values greater than 0.5 make the object brighter
than others in the scene (based on a color componant... so that you can
chose your flouro color) and biases less than 0.5 dim the object (depending
on your color componant it cuold be possible to color shift the object,
great for special effects).

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

Post a reply to this message

No, Margus is right, it's not possible to simulate it with current features,
because transmit and filter don't have the same lighting model as is
necessary to create translucent effects (for Johannes, translucency is like
the sort of effect you get from shinning light on rice paper - the shadows,
and also like candle wax - the object actually seems to have a density).
While I guess this could be simulated with media it would be very difficult
to get the right effect and would be slow to render...

What I propose is a finish statement translucency keyword...  The way the
calculation is made is by taking into account what translucency really is...
that is, non-directional diffuse reflection... (*gulp*).  Now because the
diffuse color of a surface depends on the angle between the surface normal
and the light, what you do to get translucency is ignore the surface normal
alignment... (if that makes ANY sense to ANYONE I'll be happy, because it's
hard to explain...).

Um, yeah, so there you go... also if you combined with ray distance (into
the object) with another bias value you could get a "thickness" for the
translucency... like, 0.4 would be glue, 0.8 would be wax etc etc

Anyway, just an idea...

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

Post a reply to this message

Lance Birch heeft geschreven in bericht <371041bf.0@news.povray.org>...
.......................
>What I propose is a finish statement translucency keyword...  The way the
>calculation is made is by taking into account what translucency really
is...
>that is, non-directional diffuse reflection... (*gulp*).

Now you have me confused, don't you mean "non-directional diffuse
transmission plus absorbsion"?
To me translucent is between transparent and opaque. Transparent is
glassclear and has a transmission of at least 50%, opaque has a transmission
smaller than 5% (0%), translucent has a transmission between 5% and 50% and
is not glassclear. Light passes through and is scatterd and absorbed (milky
glass).

> Now because the
>diffuse color of a surface depends on the angle between the surface normal
>and the light, what you do to get translucency is ignore the surface normal
>alignment... (if that makes ANY sense to ANYONE I'll be happy, because it's
>hard to explain...).

ingo

--
Met dank aan de muze met het glazen oog.

Post a reply to this message

Um, sort of, except that it is not necessarily how much light it lets
through, or how much you can see through it...

Opacity and transparency are messures of the same thing... (not to be
confused with transmission of course)  For example, you can give a texture a
transmission of 50%, and no matter how thick the object is, a certain amount
of light (50%) will always go through it... give it 5%, the object can be 1
unit or 1000000 units thick and 5% of the light will still get through.
What translucency does is affect the amount of light that can get through
based on the ray depth and also changes the color of the object based on a
density bias multiplier, applying this to the normal based surface lighting.

The important thing to remember is that the translucency must be object
surface normal independant to get the right effect... (only later is it
applied to the surface normal dependant shader)...

So yes, you're right about the absorbtion but you can't call it transmission
because although it will affect the transmittion of the surface, it has to
be based on the distance (the absorbtion, as you said) AND also affect the
surface itself...

The reason it's called non-directional diffuse reflection is not because it
reflects anything, but because the light reflects of it...  The
non-directional part comes from the fact that the multiplier is
non-directional but it can still be called diffuse because it affects the
diffuse of the object...

Basically to give a REALLY good example of translucency, it's just like
wax... the thicker the sheet of wax (or candle) the less light that will be
able to pass through it... AND, apart from that, the density (or
translucency bias) also affects the amount of light that can pass through...
for example, the denser the wax the less light will get through it...

Did any one get that or did I just make it more confusing?

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

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