POV-Ray : Newsgroups : povray.advanced-users : area light definition--some clarification? : Re: area light definition--some clarification? Server Time
21 Jul 2024 07:22:29 EDT (-0400)
  Re: area light definition--some clarification?  
From: Alain
Date: 31 Jan 2007 17:41:13
Message: <45c11b09$1@news.povray.org>
Kenneth nous apporta ses lumieres en ce 29-01-2007 04:46:
> "Kenneth" <kdw### [at] earthlinknet> wrote:
>> ...in
>> experiments I've done, using two simple spheres (one with no_shadow, one
>> with no_image) and a single point light just for simplicity, what I see is
>> that the final shadow, cast onto a white ground plane, is still quite dark.
>> *Almost* black...

> I took a more critical look at my own test image, and I have to conclude
> that the final shadow isn't "almost black," it IS black. The shadow (from
> the no_image sphere) is somehow taking complete precedence. There's no
> "brightness mixing" at all. Odd, but interesting. Perhaps that's just the
> logical operation of POV's shadow calculations.

> Meanwhile, my little test has presented another useful trick, something I've
> been pondering for awhile but couldn't figure out how to do, until now:
> creating a variable-density shadow. By making the pigment of the no_image
> sphere something like rgbt <1,0,0,.5> (the rgb components don't really
> matter), its shadow can be made more or less dense/dark. So that an object
> that appears to be solid (the no_shadow sphere, in my case) can cast a
> variable-darkness shadow.  May not be physically realistic, but could be a
> useful artistic tool. Likewise, using rgbf <1,0,0,.5> would cast a reddish,
> variable-density shadow.

> Ken


Are you using light_group? In that case, if the no_shadow object is in a group 
with a given light source, that light will only illuminate that object, unless I 
missunderstood the working of a light_group.

-- 
Alain
-------------------------------------------------
Don't try so hard, the best things come when you least expect them to.


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.