POV-Ray : Newsgroups : povray.binaries.images : Colors from golds.inc and metals.inc : Re: Colors from golds.inc and metals.inc Server Time
1 Mar 2024 15:59:40 EST (-0500)
  Re: Colors from golds.inc and metals.inc  
From: Bald Eagle
Date: 28 Feb 2022 17:00:00
Message: <web.621d450f93c26a371f9dae3025979125@news.povray.org>
Cousin Ricky <ric### [at] yahoocom> wrote:

> I believe the third row best matches the original colors as presumably
> intended by the POV-Team, although, for the brasses and golds, the
> second row seems closer to colors I see in real life.  What do you think?

Regarding the brass, I have a chunk of brass sitting next to me and, 4th row,
P_Brass4 decoded S pure metallic finish looks best.
P_Brass3 in that row is too dark/orange, and the second row is too
pale/unsaturated.

Most of the other colors look like crap, unless we're talking about oxidized or
heat-discolored metal.

The finish in that first row is an atrocity.  It's like there's a fog or haze.

The first brass looks like steel, and the second in the 4th row looks like
copper.

For the chromes, I'm comparing it to a pair of nail clippers - presumably chrome
plated like everything else - and P_Chrome3 in row 2 or 3 look the closest in
color tone.

For the copper, I have a 3-foot section copper rain gutter, and a 6-foot copper
downspout.   Keep in mind that pure copper rapidly acquires a thin oxide layer
that darkens the color, so I'm comparing as-is, not buffed / polished /
chemically cleaned.   The lighting also heavily factors in.
But I'd have to say that I favor P_Copper3 in the 4th row above all others, with
2 and 5 in that same row as possible alternates.


For the gold, I have a Canadian 1/4 oz 0.9999 coin.
Also, some 1 g fine gold rectangles.

This one is the hardest to determine by far.  It's extremely sensitive to angle
and lighting....
It seems to my eye to fall between the 1st and 2nd in the 4th row - but neither
one really captures the peculiar shade of orange that the metal has.
Shining a white LED onto it to get "better" light makes it a LOT more yellow.
So --- we might need a real-life Cornell Box with standardized illumination to
eliminate the many influential variables.

For the silver, I'm comparing to a 1 oz silver round.
And wow - this is devilishly hard as well.
Numbering from left to right, top to bottom, I'd say it falls somewhere in the
range of 6, 7, 8, 9, 11, 12, 13, 14, 18

16 and 17 are too yellow, and 19 is too - purple?
It's also hard to compare to the renders, since it's hard to say if I'm looking
at the color of the metal or the color of the reflection.

Maybe a different set of spheres with some normal / micronormal finishes to give
a more matte appearance might help in future assessments.

Not sure what else we have, but I'd say that at some point in the future we
ought to strive to have have iron, steel, nickel, aluminum, tin, and zinc.
And maybe titanium nitride.

I'm sure they're all wildly similar, but maybe trying to look at the real world
objects and figure out rendering textures for them might teach us to see what
we're overlooking, discover better lighting and environment for objective
observation, and maybe lump a few of those metals/platings into a catch-all
texture that works for all of that group.

No idea what, if any, effect alloying with chromium, molybdenum, vanadium, etc
would have.  I'm sure there's a difference between different steels, high
carbon, stainless, etc.   My neighbor endeavors to be a bladesmith, so maybe
he's got some bar stock samples I can look at.

Great work so far, as usual - that's a lot of meticulous work and a lot of
renders.  It's a pretty nuanced topic, for sure.


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