On 25-6-2015 22:50, clipka wrote:
> Am 25.06.2015 um 16:44 schrieb Thomas de Groot:
>> Following the discussion in povray.off-topic on Physically Based
>> Rendering (PBR)
>> http://news.povray.org/povray.off-topic/thread/%3Cop.x0kk32qvufxv4h%40xena%3E/
>>
>>
>>
>> and the /rules/ given by Clipka, this is an RSoCP following the said
>> rules and rendered with UberPOV.
>>
>> Scene file can be found in povray.binaries.scene-files.
>>
>
> Um... you're /not/ following the rules /at all/:
>
>      sphere {
>        <0,0,0>, 1.00
>        texture {
>          pigment {srgb <0.8, 0.7, 0.7>*0.5 }
>          finish {
>            diffuse albedo 0.8
>            brilliance 3, 3
>            reflection {
>              0.0, 1.0
>              //roughness 0.001
>              //fresnel on
>              //metallic on
>            }
>            fresnel on
>            metallic on
>          }
>        }
>        interior { ior 1.5 }
>
>        scale <1,1,1>  rotate <0,0,0>  translate <0,1.35,0>
>      }
>
> You're using "metallic on" in the entire finish block, but not in the
> reflection block. That's bad bractice. /Very/ bad practice.

Ah! Yes, I don't know why I switched it off. I had a reason initially 
which I have forgotten now :-/

>
> Also, "fresnel on" has no effect (or at least shouldn't have) when used
> together with "metallic on". And as I'm already at it, always use
> "fresnel on" in the reflection block when you use it in the entire
> finish block. It doesn't carry through to the reflection automatically.

I had not paid enough attention to the (mutual) exclusion of fresnel and 
metallic (RTFRules!). Forgot also to add conserve_energy.

>
> Furthermore, I'll probably need to add more rules:
>
> - Do not use "diffuse" for metallic materials (or, more specifically,
> use "diffuse 0.0" to override the non-zero default). Use specular
> reflection with a very high roughness instead. To also add crisper
> highlights to the mix, use complex textures.
>

Good one about diffuse and complex textures. My scene is simple because 
I wanted to start from the 'basic scene' in the Insert Menu.

Four images are attached with variations in the parameter use (see their 
corresponding titles).

sphere {
   <0,0,0>, 1.00
   texture {
     pigment {srgb <0.8, 0.7, 0.7>*0.5 }
     finish {
       diffuse albedo 0.0
       specular albedo 0.5
       roughness 0.001
       brilliance 3, 3
       reflection {
         0.0, 1.0
         roughness 0.001
         fresnel on
         metallic off
       }
       fresnel on
       metallic off
     }
   }
   interior { ior 1.5 }

   scale <1,1,1>  rotate <0,0,0>  translate <0,1.35,0>
}


-- 
Thomas

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Attachments:
Download 'rsocp_uber_fresnel.png' (327 KB) Download 'rsocp_uber_fresnel+specular.png' (317 KB) Download 'rsocp_uber_metallic.png' (308 KB) Download 'rsocp_uber_metallic+specular.png' (316 KB)

Preview of image 'rsocp_uber_fresnel.png'

Preview of image 'rsocp_uber_fresnel+specular.png'

Preview of image 'rsocp_uber_metallic.png'

Preview of image 'rsocp_uber_metallic+specular.png'