POV-Ray : Newsgroups : povray.binaries.images : 'solid media' human model Server Time
1 Dec 2022 02:44:57 EST (-0500)
  'solid media' human model (Message 11 to 13 of 13)  
<<< Previous 10 Messages Goto Initial 10 Messages
From: MichaelJF
Subject: Re: 'solid media' human model
Date: 17 Apr 2022 12:33:08
Message: <625c4144$1@news.povray.org>
Am 14.04.2022 um 15:32 schrieb Kenneth:
> And here's the good ol' Stanford Bunny. This is a mesh2 model made (or
> converted) by James Holsenback in October of 2014. It's available here...
> 
>
https://news.povray.org/povray.binaries.misc/thread/%3C5432afe4%40news.povray.org%3E/
> 
> There are some subtle media-related issues with this render; the media probably
> just needs more samples.
> 
One of the best Standford Bunnies I ever noticed so far. Very nice! I 
think it would look better with a more "natural" background.

The problem with this approach is that media have no surface. With some 
efforts one can color them but one has no finish and one cannot use 
features depending on a finish-statement.

Best regards
Michael


Post a reply to this message

From: Kenneth
Subject: Re: 'solid media' human model
Date: 18 Apr 2022 22:05:00
Message: <web.625e17d0d1523eea4cef624e6e066e29@news.povray.org>
MichaelJF <fri### [at] t-onlinede> wrote:

> One of the best Standford Bunnies I ever noticed so far. Very nice! I
> think it would look better with a more "natural" background.

Thanks. I was kind of 'quick and dirty' with these renders-- I was working on
something else media-related, and got sidetracked. ;-)  The cross-hatched
background is a specific one I use to test how 'solid' the media is; if I can
see the pattern, then the media isn't solid enough!
>
> The problem with this approach is that media have no surface. With some
> efforts one can color them but one has no finish and one cannot use
> features depending on a finish-statement.
>

That's true; the method does have its limitations. And scattering media itself
has a basic limitation, IMO: The 'extinction' value cannot use its own color
vector. So the extinguished parts of the media (the shadows with itself) are
always the complementary color, particularly if the media is very dense. Of
course, that's the correct paradigm for the filtering effect of the media, but
it's a 'creative' bottleneck. If extinction could use a color vector, it would
be easy to do something like...

     scattering{ 1, <0.3,0.6,0.9> extinction (1 - <0.3,0.6,0.9>)

to get 'all one color' throughout. That's why I usually use emission +
absorption medias for such 'solid' renders, rather than scattering-- which makes
it easy to give the absorbing media the complementary color. And it's faster to
render!


Post a reply to this message

From: Kenneth
Subject: Re: 'solid media' human model
Date: 18 Apr 2022 23:15:00
Message: <web.625e28fdd1523eea4cef624e6e066e29@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:
>
> ...That's why I usually use emission + absorption medias for such 'solid'
> renders, rather than scattering-- which makes
> it easy to give the absorbing media the complementary color. And it's faster to
> render!

Oops, that's not correct, sorry; emitting + absorbing media does not produce
interior 'self shadowing'; only scattering with extinction > 0 does, OR
scattering with extinction 0 + absorption.

I'm running too many media tests these days, and getting confused :-<


Post a reply to this message

<<< Previous 10 Messages Goto Initial 10 Messages

Copyright 2003-2021 Persistence of Vision Raytracer Pty. Ltd.