<ffj### [at] club-internetfr> wrote:

>I'd like to know if some of you have some tips to render metallic
>textures.
>What kind of value they give to brilliance, diffuse, ambient,.....
>If they add normal to it.....
>
>I'd like to know how the others deal with it and how they build them.

I am not an expert in any case but anyway see if my experience is of
help.

Pigment:

A solid color :) I prefer unsaturated colors for metals but of course
there are exceptions, such as copper or gold.

Finish:

I always go for a low ambient (0.05-0.2) and a diiffuse equal to
1-ambient (unless reflection is used), using a brilliance from 1.75 to
3.25, usually setting in the range 2.25-2.75. I also always use two
highlights, a tight specular in the range 0.5-1 and roughness
0.0005-0.005 and a soft phong with half the specular's intensity and a
phong_size in the range 20-5. With these, I use metallic 0.75-1,
usually 0.9 or so. Reflection is also important, but I never go over
0.5. With MegaPOV, reflect_metallic is also very helpful, as much as
metallic itself.

Normal:

I don't usually use a normal unless I want to achieve some kind of
anisotropy. In this case I use a very finely scaled normal (like scale
0.0001 - 0.001 for a unit sphere) following the direction of the
anisotropy. For example, if a brushed aluminum Utah teapot is what
you're after, you can give the lid a wood normal with a very high
frequency (1000-10000) or scaled very small. As a rule og thumb that I
use, there should be two or more complete waveforms of the normal in
every pixel. This, of course, requires antialiasing settins akin to
+am0.025 +am2 +r3 +j1.0 +patience=Godlike , but it is (still) the only
way to achieve anisotropy in POV.

Photons:

Photons help if the object is a) reflective and b) complex. It has to
have some way to reflect light onto itself and then photons make
wonders for photorealism.

Radiosity:

I've hardly used radiosity so I can't help you any here, sorry.

Maybe you'll find some of the above applicable.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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