POV-Ray : Newsgroups : povray.general : motion blur by media Server Time: 17 Jun 2019 14:04:13 GMT
  motion blur by media (Message 1 to 3 of 3)  
From: Kima
Subject: motion blur by media
Date: 28 May 2018 15:25:01
Message: <web.5b0c1e7a47d138933ce674f0@news.povray.org>
Following the suggestions made in
http://news.povray.org/povray.general/thread/%3Cweb.5b096a17747d6b9c3ce674f0%40news.povray.org%3E/

I tried to create a series of blur duplicates as the tail and came up with a
code of like

 sphere{ <0,0,0>,0.27 pigment{rgb <1,0,0>}}
 #declare Nr = 1;
 #while (Nr>0)

 sphere{ <0,0,0>,0.27 pigment{rgbf <1,1,1,Nr>}

        hollow
 interior{
  media{
   scattering{Nr,<1,1,1>}
   intervals 3
   samples 1,1
   }
 }
         translate <Nr,0,0>
       }

 #declare Nr = Nr - 0.1;
 #end

It is getting close but far from a realistic motion blur. Any suggestion?


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From: Bald Eagle
Subject: Re: motion blur by media
Date: 28 May 2018 16:40:01
Message: <web.5b0c2ff0d6fa6c8c10874a080@news.povray.org>
What you're doing is mixing a filter pigment with your media.

Make the spheres of the tail (the container for the media fully transparent.

Then to avoid the coincident surface problem, scale the spheres a little smaller
then the comet sphere.

sphere{ <0,0,0>,0.27 pigment{rgb <1,0,0>}}
 #declare Nr = 1;
 #while (Nr>0)

 sphere{ <0,0,0>,0.26 pigment{rgbt <1,1,1,1>}

        hollow
 interior{
  media{
   scattering{Nr,<1,1,1>}
   intervals 3
   samples 1,1
   }
 }
         translate <Nr,0,0>
       }

 #declare Nr = Nr - 0.1;
 #end


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From: Alain
Subject: Re: motion blur by media
Date: 28 May 2018 19:44:33
Message: <5b0c5c21$1@news.povray.org>
Le 18-05-28 à 11:21, Kima a écrit :
> Following the suggestions made in
>
http://news.povray.org/povray.general/thread/%3Cweb.5b096a17747d6b9c3ce674f0%40news.povray.org%3E/
> 
> I tried to create a series of blur duplicates as the tail and came up with a
> code of like
> 
>   sphere{ <0,0,0>,0.27 pigment{rgb <1,0,0>}}
>   #declare Nr = 1;
>   #while (Nr>0)
> 
>   sphere{ <0,0,0>,0.27 pigment{rgbf <1,1,1,Nr>}
> 
>          hollow
>   interior{
>    media{
>     scattering{Nr,<1,1,1>}
>     //intervals 3
Never use ANYTHING but the default of 1 for intrvals !
>     samples 1,1
Increase this. You only get a single sample whitch is not enough.
The default is : samples 10.
Also, the second value is always silently discarted.
>     }
>   }
>           translate <Nr,0,0>
>         }
> 
>   #declare Nr = Nr - 0.1;
>   #end
> 
> It is getting close but far from a realistic motion blur. Any suggestion?
> 
> 

For media, the defaults are :
method 3
intervals 1
samples 10

confidence is NOT used
variance is NOT used
Only the first value of samples is ever used if you provide two.
Using intervals >1 greatly impaire your rendering speed.

Using intervals with a value larger than 1 is only adviseable if using 
method 1 or 2.

As your spheres overlap, you see the boundaries. It would be beter to 
use a single larger, and fully transparent, sphere and modulate the 
media density instead.


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