I am trying to create a scene that has a visible spotlight. I've got the
spotlight showing OK but the rest of the scene is under illuminated. The spot
and the target are in a Media Container. I have added two omni lights that don't
react with Media but they don't do a lot. If I make the omni lights react with
Media I get a whiteout. I'm doing this in Moray so a scene would have a lot of
junk in it.

The Media settings are:
      texture
      {      
         pigment
         {
            color rgbf <1.0, 1.0, 1.0, 1.0>
         }
      }   
      interior
      {
         media  // MyAtmosphere_1_1
         {
            variance 1.0/128.205128
            scattering
            {
               1 ,  rgb <1.0, 1.0, 1.0> // isotropic scattering
               extinction 0.15
            }
         }
      }

Regards
        Stephen

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"Stephen McAvoy" <mcavoys(at)AOLdotCOM> wrote in message
news:qu53vvosn5it1kkor4vts10ajlpu6agfod@4ax.com...
> I am trying to create a scene that has a visible spotlight. I've got the
> spotlight showing OK but the rest of the scene is under illuminated. The
spot
> and the target are in a Media Container. I have added two omni lights that
don't
> react with Media but they don't do a lot. If I make the omni lights react
with
> Media I get a whiteout. I'm doing this in Moray so a scene would have a
lot of
> junk in it.

Common occurance when dealing with scattering media, it obscures things like
smokey air. You have the color value at rgb 1.0 (scattering amount) which is
typically too high to see through. While that can make a light source
brighter in its vicinity it doesn't work well at a distance, nor for objects
more distant from the camera. Also, even if you lower extinction to zero it
remains as opaque as before and doesn't help with transparency. So, you'll
need to lower the scattering color values instead. Can also use a density
statement with smaller value than the default of rgb 1. Basically, you'll be
adjusting all those values until you get what looks appropriate.

As to the additional lights you added to help illuminate the scene... I
would say you would cause unwanted affects (hilights, diffuse surfaces,
oversaturation) by brightening the scene using those (with large light
source color values), so probably not a good idea to do that.

-- 
Bob H.
http://www.3digitaleyes.com

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On Tue, 30 Dec 2003 11:16:21 -0600, "Hughes, B." <omn### [at] charternet> wrote:

>Can also use a density
>statement with smaller value than the default of rgb 1. Basically, you'll be
>adjusting all those values until you get what looks appropriate.

That did it. Density with a gradient in the up direction works.

>As to the additional lights you added to help illuminate the scene... I
>would say you would cause unwanted affects (hilights, diffuse surfaces,
>oversaturation) by brightening the scene using those (with large light
>source color values), so probably not a good idea to do that.

Is that a lucky guess? :-}

I'll have to work on this. One thing I found is that the spotlight does not give
the characteristic illuminated ellipse on the floor so I needed a second one
that does not react with media.
Thanks Bob.

Regards
        Stephen

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"Stephen McAvoy" <mcavoys(at)AOLdotCOM> wrote in message
news:dak3vv4rbenfosgdr5ju5arqpobt9lfv93@4ax.com...
> On Tue, 30 Dec 2003 11:16:21 -0600, "Hughes, B." <omn### [at] charternet>
wrote:
>
> >Can also use a density
> >statement with smaller value than the default of rgb 1. Basically, you'll
be
> >adjusting all those values until you get what looks appropriate.
>
> That did it. Density with a gradient in the up direction works.

Even better, good to know you worked something out like that for it. Just
remember that light scattering in the air might be from particles floating
at the ceiling, or descended to the floor, at some intermediate level, or
turbulated around too. :-)

> >As to the additional lights you added to help illuminate the scene... I
> >would say you would cause unwanted affects (hilights, diffuse surfaces,
> >oversaturation) by brightening the scene using those (with large light
> >source color values), so probably not a good idea to do that.
>
> Is that a lucky guess? :-}

Educated guesses, usually.

> I'll have to work on this. One thing I found is that the spotlight does
not give
> the characteristic illuminated ellipse on the floor so I needed a second
one
> that does not react with media.

Not sure why you aren't seeing one, except maybe from light fading or media
attenuation causing dimming too much before reaching the floor. Or if the
floor finish has a low diffuse value too.

I'll post an example image at p.b.i. showing isotropic scattering media
having a few different values. It never is easy to fine-tune media together
with the lights, backgrounds, and objects. Probably because there can be
more to the visual perception than a texture alone has, at the risk of being
somewhat philosophical about it. ;-)

-- 
Bob H.
http://www.3digitaleyes.com

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Stephen McAvoy wrote:
> I am trying to create a scene that has a visible spotlight. I've got the
> spotlight showing OK but the rest of the scene is under illuminated.

Try negative absorbtion.  (check out my 'haze' texture that's with
the user-submitted library in M 3.5 for reference)

-- 
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------

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On Tue, 30 Dec 2003 17:32:59 -0500, Tim Cook <z99### [at] bellsouthnet> wrote:

>Try negative absorbtion.  (check out my 'haze' texture that's with
>the user-submitted library in M 3.5 for reference)

Oh I thought that I had used your haze as a starting point but since it is
direct code I can't have. It must have been one posted in moray.binaries by Arne
Kleinophorst. I'll try that tomorrow as I'm in the middle of a longish render
just now. In fact I might post it in pov.b.images so someone can tell me what
the deliberate mistake is. BTW I really liked your post with the Poser 5 model
especially the clothes and hair.

Regards
        Stephen

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On Tue, 30 Dec 2003 16:00:40 -0600, "Hughes, B." <omn### [at] charternet> wrote:

> Just
>remember that light scattering in the air might be from particles floating
>at the ceiling, or descended to the floor, at some intermediate level, or
>turbulated around too. :-)

Arrg! Every time I sit in the theatre I want to do the smoke/dry ice effect. 

>Not sure why you aren't seeing one, except maybe from light fading or media
>attenuation causing dimming too much before reaching the floor. Or if the
>floor finish has a low diffuse value too.

The floor finish is the BoisJaune wood texture in a brick pattern and I'm not
using attenuated by media. I'll post a render I'm doing just now, later. 

>I'll post an example image at p.b.i. showing isotropic scattering media
>having a few different values. It never is easy to fine-tune media together
>with the lights, backgrounds, and objects. Probably because there can be
>more to the visual perception than a texture alone has, at the risk of being
>somewhat philosophical about it. ;-)

Thanks for the post, again, I'll experiment tomorrow. As for visual perception
it is funny what you think you see. I am sure that when the eye sees an object
the brain remembers it and when it looks at another object, in RL the brain puts
together a composite picture. Like rendering different parts of the view with
their own optimum settings

Regards
        Stephen

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