I'm having some difficulty with scattering media:

The first problem has to deal with if I have spotlights instead of point
lights, the media turns to random noise.

The second problem is, When I get the scattering media just right, when I
wrap the object in a glass, it seems darker than it was.

The third problem, after compensating for the first problem, When photons
are turned on, it's either too dark or totally washed out and tends to look
a bit splotchy.

My current photons setup is as folows:

            photons
            {
                spacing 0.05
                media 100
            }

Any ideas?

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"Michael Raiford" <mra### [at] hotmailcom> wrote in message
news:3ffa100a@news.povray.org...
> I'm having some difficulty with scattering media:

Join the club ;) - media, particularily when you start mixing it with other
special effects, such as photons, can be tricky to get right.

Could you post a more complete scene? (not necessarily your actual scene - just
a simplified version but showing the problem).

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Tom Melly wrote:

>Join the club ;) - media, particularily when you start mixing it with other
>special effects, such as photons, can be tricky to get right.
>
>Could you post a more complete scene? (not necessarily your actual scene - just
>a simplified version but showing the problem).


I think I might have it close to where I want it. I'll post the scene
file(s) when I get home tonight.  I lowered the spacing on the photons
(afer adjusting my swapfile size so POVRay can take up about 300M of
memory), and it looked much closer to what I wanted, but if I'm able to get
any more tips for how to get it to look even better, then that's great.
It's spread across a few includes at the moment, and I have no problem
sharing what I have (I intend to post the includes I'm creating when they
are finalised on my website anyway).

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In article <3ffa100a@news.povray.org>,
 "Michael Raiford" <mra### [at] hotmailcom> wrote:

> The first problem has to deal with if I have spotlights instead of point
> lights, the media turns to random noise.

Increase the number of samples. You're just not using enough samples to 
accurately render the variation in lighting from the spotlights.


> The second problem is, When I get the scattering media just right, when I
> wrap the object in a glass, it seems darker than it was.

You excluded the media from the area of the object by putting a 
non-hollow object around it. Or there's something odd with the texture 
you're using.


> The third problem, after compensating for the first problem, When photons
> are turned on, it's either too dark or totally washed out and tends to look
> a bit splotchy.

It gets dark when photons are on because the shadow of a transparent 
object is then illuminated only by photons, light no longer passes 
directly through the glass. In real life, the shadow is also illuminated 
by diffusely scattered light and by other light sources, in POV-Ray you 
can use radiosity and multiple light sources to get more accurate 
lighting.

You'll need to post more of the scene to get more detailed help...

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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I've zipped-up the scene and posted it on p.b.sf, as well as the current
progress of the image (rendering is very slow: 12hrs and only half done.)


"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3ffa7e9b$1@news.povray.org...
> "Michael Raiford" <mra### [at] hotmailcom> wrote in message
> news:3ffa100a@news.povray.org...
> > I'm having some difficulty with scattering media:
>
> Join the club ;) - media, particularily when you start mixing it with
other
> special effects, such as photons, can be tricky to get right.
>
> Could you post a more complete scene? (not necessarily your actual scene -
just
> a simplified version but showing the problem).
>
>

Post a reply to this message