POV-Ray : Newsgroups : povray.binaries.images : Averaged normals vs. averaged textures Server Time
30 Jul 2024 16:14:41 EDT (-0400)
  Averaged normals vs. averaged textures (Message 1 to 4 of 4)  
From: Cousin Ricky
Subject: Averaged normals vs. averaged textures
Date: 9 Aug 2011 14:05:01
Message: <web.4e4175bb14a73acc85de7b680@news.povray.org>
I was trying to create a stand-alone normal for blurred reflections.  The sphere
on the left uses an averaged texture, as illustrated in the Knowledgebase.  The
sphere on the right uses an averaged normal applied to a base texture.
_____________________________________________________________

#version 3.7;

global_settings
{  assumed_gamma 1
   max_trace_level 10
}

camera
{  location <-8, 1.5, -8>
   look_at y
   angle 30
}

sky_sphere
{  pigment
   {  gradient y color_map
      {  [0 rgb <0.7, 0.8, 0.9>]
         [1 rgb <0.2, 0.3, 0.6>]
      }
   }
}

light_source
{  <-1, 2, 0> * 1000 rgb 1
   parallel point_at 0
}

plane { y, 0 pigment { checker rgb 0.05 rgb 1 } }

#declare t_Brass = texture
{  pigment { rgb <0.80, 0.57, 0.23> }
   finish
   {  reflection { 0.5 metallic }
      diffuse 0.4 ambient 0.05
      specular 1 metallic 0.95 roughness 0.015
      brilliance 6.75
   }
}

#declare S = seed (0);

sphere
{  y, 1
   texture
   {  average texture_map
      {  #declare I = 0;
         #while (I < 10)
            [1 t_Brass
               normal
               {  bumps
                  translate <rand(S), rand(S), rand(S)> * 100
                  scale 1000
               }
            ]
            #declare I = I + 1;
         #end
      }
   }
   translate <-1, 0, 1>
}

#declare S = seed (0);

sphere
{  y, 1
   texture
   {  t_Brass
      normal
      {  average normal_map
         {  #declare I = 0;
            #while (I < 10)
               [1 bumps
                  translate <rand(S), rand(S), rand(S)> * 100
                  scale 1000
               ]
               #declare I = I + 1;
            #end
         }
      }
   }
   translate <1, 0, -1>
}
_____________________________________________________________

By my understanding of SDL, the two spheres should be identical.  Obviously, my
understanding is wrong, but I cannot figure out where the difference is.  Why
are the two spheres different?

I am using version 3.7RC3.


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averagendemo.jpg


 

From: Warp
Subject: Re: Averaged normals vs. averaged textures
Date: 9 Aug 2011 15:11:25
Message: <4e41865d$1@news.povray.org>
On 08/09/2011 09:00 PM, Cousin Ricky wrote:
> I was trying to create a stand-alone normal for blurred reflections.  The sphere
> on the left uses an averaged texture, as illustrated in the Knowledgebase.  The
> sphere on the right uses an averaged normal applied to a base texture.

   When you average textures, POV-Ray will calculate each texture 
independently and then average the results. If you average normals, the 
resulting normals are average of the given normals, and used only once. 
It's just how it has been implemented.


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From: Alain
Subject: Re: Averaged normals vs. averaged textures
Date: 9 Aug 2011 15:16:27
Message: <4e41878b@news.povray.org>

> I was trying to create a stand-alone normal for blurred reflections.  The sphere
> on the left uses an averaged texture, as illustrated in the Knowledgebase.  The
> sphere on the right uses an averaged normal applied to a base texture.
> _____________________________________________________________

> _____________________________________________________________
>
> By my understanding of SDL, the two spheres should be identical.  Obviously, my
> understanding is wrong, but I cannot figure out where the difference is.  Why
> are the two spheres different?
>
> I am using version 3.7RC3.

I had the same assumption as you. I also did notice that with both 
version 3.6 and 3.7.

I don't know why, but as the result did not change between 3.6 and 3.7, 
I must assume that's by design.


Alain


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From: Cousin Ricky
Subject: Re: Averaged normals vs. averaged textures
Date: 9 Aug 2011 17:35:00
Message: <web.4e41a718b9efd2685de7b680@news.povray.org>
Warp <war### [at] tagpovrayorg> wrote:
>    When you average textures, POV-Ray will calculate each texture
> independently and then average the results. If you average normals, the
> resulting normals are average of the given normals, and used only once.
> It's just how it has been implemented.

I see.  Thanks.


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