POV-Ray : Newsgroups : povray.binaries.images : Ambient and cast shadows on metallic textures : Re: Ambient and cast shadows on metallic textures Server Time
19 May 2024 22:20:03 EDT (-0400)
  Re: Ambient and cast shadows on metallic textures  
From: Cousin Ricky
Date: 24 Nov 2021 22:22:23
Message: <619f016f@news.povray.org>
On 2021-11-24 11:14 PM (-4), Cousin Ricky wrote:
> It has become conventional wisdom around here, perhaps started by
> clipka, that metallic finishes should have zero ambient, and Alain has
> been carrying that banner ever since.  [...]
> [snip]
> However, I have examined less shiny metallic surfaces, and they do
> reveal faint cast shadows--the duller the surface, the more prominent
> the shadow.  This implies the real-life equivalent of a 'diffuse'
> component to these metals, and I do not see how a texture can have a
> diffuse component without picking up diffuse environmental light--i.e.,
> a non-zero ambient.

Since clipka has been posting about metallic finishes, over the years I
have been increasing the specular reflection and decreasing the diffuse
& ambient in my metallic textures.  This can be seen longitudally in
some of my Object Collection modules.  I am reconsidering the
AndroidRobot finish, though, for whenever Google next revises the robot;
I think the robot looks better semi-metallic.

For most metal surfaces, I'm finding this a good finish:

  { reflection { 0.9 metallic }
    diffuse 0.05
    ambient 0.05 * whatever_your_general_scene_ambient
    emission 0 // Suppresses 3.8's high ambient warning
    specular albedo 1 metallic
    roughness 0.0001 // or higher

For polished surfaces:

  { reflection { 1 metallic }
    diffuse 0
    ambient 0
    specular albedo 1 metallic
    roughness 0.0001 // or lower

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