Op 22-2-2022 om 14:36 schreef Cousin Ricky:
> When Thomas de Groot challenged Alain and me to write improved
> metals.inc, one of my first thoughts was "Why bother? It's a lost
> cause."  Alain's solution was to just replace all the ambients with 0,
> but I think that's too simplistic.  That file and golds.inc were written
> before POV-Ray had metallic reflection.  File golds.inc goes through an
> elaborate ritual to compensate for this deficiency, while metals.inc
> ignores the problem completely.  Everything about those two files
> screams "OBSOLETE!"  But the challenge still gnaws at me.
> 
> One question that must be answered is should we assume that the colors
> are gamma pre-encoded?  Image stock_metal_gamma-srgb.jpg assumes that
> they are, and uses the srgbft keyword to decode them.  Image
> stock_metal_gamma-linear.jpg assumes they are not, and just uses the
> colors as-is.  Comparing them, it seems to me that the colors were not
> pre-encoded, unlike those in colors.inc.
> 
> Both images use assumed_gamma 1, and the spheres use this finish:
> 
>    finish
>    { ambient 0 diffuse 0
>      reflection { 1 metallic }
>      specular albedo 1 metallic
>      roughness 1 / 3000
>    }
> 
> Of course, any improvements to these files will cause old scenes to look
> different.  Better, but different.

I truly appreciate your thoughts and efforts. To address your last 
comment: I am increasingly convinced that trying at all costs to find 
solutions, at the same time preserving the aspect of old scenes, is a 
dead end. I would strongly be in favour of making those textures up to 
date, whatever the costs. For older scenes, there still are the older 
POV-Ray versions available if necessary.

-- 
Thomas

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