Hi, I have a media related question.
If I trace two transparent sphere with a smoke-like media inside, everything
is fine. If I dare tracing three or more in my scene, I get to see the
interior surface of the spheres as black patches.

I have provided more details of what I do below. The whole smoke process is
inspired from the IRTC entry Strike that won the "First contact" round in
98. Their code does not run as is. I use POV 3.5.

cheers,

Christian


First lets pretend I have the following
code (by memory).

#declare tex =
texture{ pigment {rgbf<1,1,1,1>}
            finish{ambient 0 diffuse 1}}

#declare int =
interior{
            media{
                    scattering {1, <...> emission 1.0}
                    density{
                            spherical
                            color_map{...}
                            turbulence 0.5
                    }

            }

}

#declare mymat =
material{
    texture{tex}
    interior{int }
}

if I create only two sphere:

sphere {<0,0,0> 200 material{mymat}}
sphere {<0,0,0> 200 material{mymat} translate 100*y}

I get a beautiful smoke column made of two chunks of smoke. But if I add a
third sphere:

sphere {<0,0,0> 200 material{mymat} translate 200*y}

I get a beautiful column, but the interior surface of the spheres shows as
black patches. If I merge two of the spheres, I get no patches but the third
sphere is cut-off and the shadow cast by the smoke is also cut-off. I also
tried union of these spheres, with no good results.

Post a reply to this message

"bongotastic" <cbl### [at] csdalca> wrote:
> Hi, I have a media related question.
> If I trace two transparent sphere with a smoke-like media inside, everything
> is fine. If I dare tracing three or more in my scene, I get to see the
> interior surface of the spheres as black patches.
<snip>
>
> #declare tex =
> texture{ pigment {rgbf<1,1,1,1>}
>             finish{ambient 0 diffuse 1}}
>

I know teacher, I know!  <waving hand wildly>

I had this same problem when I was learning to play with media. Try removing
the filter component of your pigment.

RG

Post a reply to this message

In article <web.40aba571c1340bc7a0c272b50@news.povray.org>,
 "gonzo" <rgo### [at] lansetcom> wrote:

> I know teacher, I know!  <waving hand wildly>
> 
> I had this same problem when I was learning to play with media. Try removing
> the filter component of your pigment.

That would make it impossible to see the media at all.

The problem is a too-low max_trace_level. The default is 5, but with 3 
spheres, you can see through up to 6 surfaces. POV just stops after the 
fifth surface, using the background color rather than tracing more rays. 
Just put a higher max_trace_level in global_settings. I generally leave 
it around 12, you'll need to go higher in situations where you can see 
through a lot of transparent surfaces or reflections.

-- 
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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Yes, I found this out tonight just as I was reading your post. Thanks!!

Christian

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