POV-Ray : Newsgroups : povray.general : Media again? Server Time
11 Aug 2024 09:21:24 EDT (-0400)
  Media again? (Message 1 to 8 of 8)  
From: Bill DeWitt
Subject: Media again?
Date: 20 Aug 1999 09:57:06
Message: <37bd5eb2@news.povray.org>
I am making a lightsabre using media and it looks great until I get it in a
scene. Then it becomes transparent. Unless the background id dark, you can't
see it. I am using emitting and scattering in a multiple density media. I've
tested a lot of variations. Anyone know what I am missing? My media looks
like this...


cylinder { < 0.0, 1.0, 0.0 >, < 0.0,-1.0, 0.0 > 0.2

                pigment { rgbt 1.0 }

erior{ 
                          
                media { 
                        intervals 5
                        samples 12, 48 
                        emission  rgbt  1 
                        /// absorption rgbf < 0.0, 0.0, 5.0, 0.0 >
                        /// scattering { 1, rgb < 0.0, 0.0, 3.0 > }  
                   
     density { cylindrical 

                     color_map {
                                
                                [ 0.00 rgb < 0.0, 0.0, 0.0 > ]
                                [ 0.50 rgb < 0.0, 0.0, 0.5 > ]
                                [ 1.00 rgb < 0.0, 0.0, 3.0 > ]
                                
                               }                      
                                
                               scale < 0.2, 1.25, 0.2 > 
                               translate < 0.0, 0.0, 0.0 >  

              } /// end den 
                                 
     density { gradient y 

                     color_map {
                                
                                [ 0.00 rgb < 0.0, 0.0, 0.0 > ]
                                [ 0.20 rgb < 0.0, 0.0, 1.0 > ]
                                [ 1.00 rgb < 0.0, 0.0, 1.0 > ]
                                
                               }                      
                                
                               scale < 0.05, 2.0, 0.05 > 
                               translate < 0.0, 1.25, 0.0 >  

              } /// end den 
                           
            } ///end media     
          }///end sphere 
      

      hollow

    }///end


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From: Chris Huff
Subject: Re: Media again?
Date: 20 Aug 1999 10:50:37
Message: <37BD6B6A.C6F22EE0@compuserve.com>
First, are you scaling it to a different size? Media is affected by
scale, if you make it smaller you will see the media less, if you make
it larger, you will see a denser media.
Second, are you using a black or dark background to model it against?
You will have to increase the density to see it against a lighter color.
This is the method I use to adjust density:
emission  rgb < 1, 1, 1>*density


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From: Bill DeWitt
Subject: Re: Media again?
Date: 20 Aug 1999 15:19:38
Message: <37bdaa4a@news.povray.org>
Chris Huff <Chr### [at] compuservecom> wrote in message
news:37BD6B6A.C6F22EE0@compuserve.com...
> First, are you scaling it to a different size? Media is affected by
> scale, if you make it smaller you will see the media less, if you make
> it larger, you will see a denser media.
> Second, are you using a black or dark background to model it against?
> You will have to increase the density to see it against a lighter color.
> This is the method I use to adjust density:
> emission  rgb < 1, 1, 1>*density
>
>

    Even scaling the density by 100 I get the same results. See images in
p.b.i


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From: Chris Huff
Subject: Re: Media again?
Date: 20 Aug 1999 16:08:52
Message: <37BDB603.65E82BFF@compuserve.com>
Have you tried eliminating the transparency from the colors? The
transmit in the emission color, specifically.


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From: Bill DeWitt
Subject: Re: Media again?
Date: 20 Aug 1999 17:00:00
Message: <37bdc1d0@news.povray.org>
Yes, but good Idea... I've really tried so many things that I had to go and
try it again to be sure, but it seemed to make no difference.

I've now rebuilt the media from scratch to make sure I didn't have something
stupid that I couldn't spot, but still can't see it in a bright scene.

BTW, I've reposted the images at about 1/20 the file size...


Chris Huff <Chr### [at] compuservecom> wrote in message
news:37BDB603.65E82BFF@compuserve.com...
> Have you tried eliminating the transparency from the colors? The
> transmit in the emission color, specifically.
>


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From: Peter Popov
Subject: Re: Media again?
Date: 20 Aug 1999 21:55:44
Message: <37bf077c.25241982@204.213.191.228>
Add an absorbing media using the same density but inverse colors.
Where you have emitting blue put absorbing yellow, same with red and
cyan etc. Leave black as is (do not make it white) because it (black)
serves as transparency in media.


Peter Popov
ICQ: 15002700


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From: Bill DeWitt
Subject: Re: Media again?
Date: 20 Aug 1999 22:56:29
Message: <37be155d@news.povray.org>
If you meant what I just found out, you are right. (See p.b.i.)

It is in the rgb values of the emission and scattering statements that you
need to balance the numbers, not in the densities. I had been using...

emission rgb 1
scattering rgb < 1,1,0 >
density     [ rgb <0.0,1>]

when it should have been...

emission rgb <0.0,1>
scattering rgb < 1,1,0 >
density     [ rgb 1 ]

I still have some adjusting to do but at least now I can see it...


Peter Popov <pet### [at] usanet> wrote in message
news:37bf077c.25241982@204.213.191.228...
> Add an absorbing media using the same density but inverse colors.
> Where you have emitting blue put absorbing yellow, same with red and
> cyan etc. Leave black as is (do not make it white) because it (black)
> serves as transparency in media.
>
>
> Peter Popov
> ICQ: 15002700


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From: Bob Hughes
Subject: Re: Media again?
Date: 21 Aug 1999 15:25:39
Message: <37befd33@news.povray.org>
You stated a multiplication of emission rgb by a "density". Hope you
aren't thinking this produces denser media. Looks like you may be
getting yourself on the right track though. Try raising the 'density'
rgb to compensate for lighter backgrounds while lowering the
scattering and emission (absorption also), you might even be able to
comment out 'scattering' completely, it's awfully slow anyway. The
variations of media environments is not easy to control from what I've
seen of it so far (nooooo :)  Good luck to you anyhow.

Bob

Bill DeWitt <the### [at] earthlinknet> wrote in message
news:37be155d@news.povray.org...
> If you meant what I just found out, you are right. (See p.b.i.)
>
> It is in the rgb values of the emission and scattering statements
that you
> need to balance the numbers, not in the densities. I had been
using...
>
> emission rgb 1
> scattering rgb < 1,1,0 >
> density     [ rgb <0.0,1>]
>
> when it should have been...
>
> emission rgb <0.0,1>
> scattering rgb < 1,1,0 >
> density     [ rgb 1 ]
>
> I still have some adjusting to do but at least now I can see it...
>
>
> Peter Popov <pet### [at] usanet> wrote in message
> news:37bf077c.25241982@204.213.191.228...
> > Add an absorbing media using the same density but inverse colors.
> > Where you have emitting blue put absorbing yellow, same with red
and
> > cyan etc. Leave black as is (do not make it white) because it
(black)
> > serves as transparency in media.
> >
> >
> > Peter Popov
> > ICQ: 15002700
>
>


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