"Tim Cook" <z99### [at] bellsouthnet> wrote in message
news:3eb19b77@news.povray.org...
> Slime wrote:
> > Is negative absorption the same as emission?
>
> Nope.  Emission simulates the media actually generating
> energy, whereas absorption simulates removal of energy;
> removal of negative energy isn't exactly the same as
> generating energy, it's more of a cancelling force than
> an additive force.

Surely it's more of a multiplying force? so things viewed through negative
absorption will have their colour increased by it, multiplicitavely. i.e. black
things will stay black which they won't with emission.

It's a nice effect in any case :)

--
Tek
http://www.evilsuperbrain.com

Post a reply to this message

> Surely it's more of a multiplying force? so things viewed through negative
> absorption will have their colour increased by it, multiplicitavely. i.e.
black
> things will stay black which they won't with emission.


Is that how it works? I know that emission is additive, but i never figured
out how absorption works. I imagine it involves some sort of complicated
integral, since it seems to be sort of like an infinite number of
nearly-transparent thin layers.

I always wonder about the math behind these things.

 - Slime
[ http://www.slimeland.com/ ]

Post a reply to this message

Well absorption works exactly the same as black fog. I worked the maths out for
fog once:

For example, if visibility at 1 metre is 90%, then at 2 metres it will be 90% of
90%, i.e. 81%. Basically  visibility = pow( visibility at distance of 1,
distance )

Absorption is kind of the other way round, so if you have 10% absorption you
have 90% visibility (though don't ask me how pov's density and stuf comes into
it). So, negative absorption actually increases visibility!

--
Tek
http://www.evilsuperbrain.com

"Slime" <slm### [at] slimelandcom> wrote in message news:3eb1a665$1@news.povray.org...
> > Surely it's more of a multiplying force? so things viewed through negative
> > absorption will have their colour increased by it, multiplicitavely. i.e.
> black
> > things will stay black which they won't with emission.
>
>
> Is that how it works? I know that emission is additive, but i never figured
> out how absorption works. I imagine it involves some sort of complicated
> integral, since it seems to be sort of like an infinite number of
> nearly-transparent thin layers.
>
> I always wonder about the math behind these things.
>
>  - Slime
> [ http://www.slimeland.com/ ]
>
>

Post a reply to this message

Looks nice.  Makes me think of Anne Rice for some reason.  Maybe the mix 
of balcony and metaphysics.

Post a reply to this message

"Tim Cook" <z99### [at] bellsouthnet> wrote in message
news:3eb186c6@news.povray.org...

The balcony railing looks to me to be conspicuosly non-detailed when
compared to the nice detail level of the rest of the image.

 -Shay

------------------------------------------------------------------------
--------

Post a reply to this message

On Thu, 01 May 2003 16:42:33 -0400, Tim Cook <z99### [at] bellsouthnet>
wrote:

>Please submit any suggestions/comments before I embark on
>another week-long attempt to render it with the scattering
>media and photons.

I don't know how you did this, but this is the best computer-generated
hair I've seen second only to Final Reality (the movie).


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

Post a reply to this message

Peter Popov wrote:
> I don't know how you did this, but this is the best computer-generated
> hair I've seen second only to Final Reality (the movie).

Final Fantasy, perhaps?  Actually the hair I'm using is pretty cheap,
it needs tweaking yet, I doubt it'd hold up to a close-up.

-- 
Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

Post a reply to this message

3eb93bb0@news.povray.org...
> Final Fantasy, perhaps?  Actually the hair I'm using is pretty cheap,
> it needs tweaking yet, I doubt it'd hold up to a close-up.

It's Kozaburo's Alice hair, right? Kozaburo's hair holds up quite nicely in
close-up :)
http://www.oyonale.com/ldc/images/fermeture_detail5.jpg
I think Kozaburo has a photoshop tutorial about painting hair on his site.

G.
--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

Post a reply to this message

Gilles Tran wrote:
> It's Kozaburo's Alice hair, right? Kozaburo's hair holds up quite
 > nicely in close-up :)

It might hold up nicely in close-up, but probably not just dumped
directly over from Poser with no correcting of the texture's
properties inside of POV...as it is I already did some tweaking,
but will go in later and see how much better I can make it.  I
think one thing I did that makes it look better is using a bump
map (which I just slapped the texture map on as a bump map too).

-- 
Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

Post a reply to this message

On Wed, 07 May 2003 13:00:36 -0400, Tim Cook <z99### [at] bellsouthnet>
wrote:

>Final Fantasy, perhaps?

That, too :)

>Actually the hair I'm using is pretty cheap,
>it needs tweaking yet, I doubt it'd hold up to a close-up.

I'd really appreciate some insights into how you did it anyway, if you
feel like putting up the time to do that.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

Post a reply to this message