POV-Ray : Newsgroups : povray.binaries.images : Ambient and cast shadows on metallic textures : Re: Ambient and cast shadows on metallic textures Server Time
29 Nov 2021 18:13:11 EST (-0500)
  Re: Ambient and cast shadows on metallic textures  
From: Cousin Ricky
Date: 25 Nov 2021 14:00:51
Message: <619fdd63$1@news.povray.org>
On 2021-11-25 1:06 PM (-4), Alain Martel wrote:
> 
> I came to the conclusion that metallic finishes should have zero ambient
> through my own experimentation. The metallic textures from the various
> includes looked just wrong to me.

Yes, they do look horrible!  My experiments with better metallic
textures began very soon after I downloaded POV-Ray.

> I started by commenting out the
> ambient. I got a massive improvement. Then, I tested with an explicit
> zero ambient and got the best, most realistic, result.

As I implied in the OP, I adopted the policy of reducing the ambient in
proportion to the diffuse, and wrote a macro to do this automatically.
Since a highly specular surface would have a low diffuse component, this
naturally leads to very low ambients.  But the ambients in metals.inc
are *way* out of proportion to the diffuse components!

> When I first posted about it, I was unaware of Clipka's position on that
> subject.
> 
> The metallic finishes from metals.inc have been made to look acceptable
> in an empty scene against a black background, and that's the only
> situation where they look somewhat correct.

Or, how about using a bright sky_sphere along with a large hollow black
sphere with no_reflection.  Our realistic low-ambient and no-ambient
metals will show up fine, no need for metals.inc's insane ambients.


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