Op 21/11/2020 om 22:54 schreef Norbert Kern:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> What I always find difficult to emulate is the light combined with the
>> texture/transparency of the leaves. I have your technique about the
>> leaves (faked translucency mapping) and also use double_illuminate. It
>> is the atmospheric media which is often difficult to do. Isotropy is
>> fairly straightforward, but I often prefer the use of Henyey-Greenstein
>> scattering withou too extreme eccentricity.
>>
>> --
>> Thomas
> 
> 
> 
> Hi Thomas,
> 
> in my last images I divide them in a diffuse and a media part. It doubles the
> render times, but there is no way to reproduce the quality when doing it
> combined.
> 
> I'm not totally sure, but some related issues seem to evaporate by this approach
> too...
> The way I do the media render is to simply multiply the diffuse, specular, phong
> and reflection values with zero (I hate this procedure by the way).
> 

Interesting. So, if I understand you correctly, you combine two separate 
renders, one without media but with fullfledged finish, and one with the 
media but with zeroed finish. Forgive me, I think you have already 
explained this in the past, but I cannot find the place.

> 
> And wow, you are really in the media types - fantastic!
> I simply tested the media types and used the best looking - here's my setup

The media type used depends heavily imo of the light position in the 
scene and the effect wanted. Sometimes, isotropic media is just fine, 
sometimes you need a more sophisticated approach.

> 
> 
> #version 3.7;
> 
> global_settings {
>          assumed_gamma 1
>          max_trace_level 5
>          noise_generator 2
> }
> 
> #include "stdinc.inc"
> 
> light_source {
>          <0,0,95131>,
>          srgb 2.5
>          area_light <1000,0,0>, <0,1000,0> 5,5 adaptive 0 jitter circular orient
>          rotate <-52,160,0>
> }
> 
> box {
>          <-35,-0.8,-80>, <35,90,30>
>          hollow
>          material {
>                  texture {
>                          pigment {color rgbt 1}
>                  }
>                  interior {
>                          media {
>                                  scattering {3, 0.005}
>                                  intervals 1
>                                  samples 50
>                          }
>                  }
>          }
> }
> 
> I mostly use standard finishes (65 meshes used in this image, perhaps 250
> textures - no way to adapt them all individually - so "finish {specular 0.3
> roughness 0.0003 diffuse 0.6 ambient 0}" has to do it...
> 

Thanks indeed. I shall play with this.

-- 
Thomas

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