Am 24.11.2017 um 17:38 schrieb B. Gimeno:
> Hi,
> After many years of coding, the realistic finish has never been my best point.
> Wow could I fix the unrealistic finish of these spheres?
> The more I look at them, the more "fake" they look on the image.
> I can't find the right combination of ambient, radiance and brilliance.

Ambient: Never looks realistic. Ditch it. Use radiosity instead (which
as of `#version 3.7` disables ambient; if you need emissive surfaces,
use `emission` in the finish).

Brilliance: Unrealistic hack. Forget it.

Radiance: Don't know what you mean by that in this context.


`metallic` is only reasonable for metals, special metallic paints, or
plastic with metal particles.

Whenever you use `specular` (or `phong`), technically you should also
use `reflection`, and make sure that the parameters correspond well. In
practice this means that you should always use the `specular albedo N`
syntax, where N is the same value as in `reflection`, and you should use
very low `roughness` because official POV-Ray can't do rough reflections
(you'd need UberPOV's blurred reflections for that). If you need dull
surfaces, either turn off highlights entirely, or use micronormals to
control the effective roughness for both reflections and highlights.

If you use reflections (and, as stated above, you always should wherever
you use highlights), you should use either `fresnel on` or `metallic on`
in the reflection block (don't forget to set an ior; even opaque
materials have one). To keep highlight parameters in sync, you should
also use `freshel on` or `metallic on` in the finish block itself.

Make sure the material doesn't reflect more light diffusely than it
receives. The easiest way to accomplish this is to use the `diffuse
albedo FLOAT` syntax, and make sure the parameter doesn't exceed 1.0.

Make sure the material doesn't reflect more light as highlights than it
receives from light sources. The easiest way to accomplis this is to use
the `specular albedo FLOAT` or `phong albedo FLOAT` syntay, and making
sure the sum of specular and phong doesn't exceed 1.0.

Make sure the material doesn't reflect more light in ANY way than it
receives from light sources. If you're using `fresnel on` (or, IIRC,
`metallic on`) at the finish level, this is as easy as following the
above two rules. Otherwise, stick to the `albedo` syntax and make sure
the sum of diffuse, specular and phong doesn't exceed 1.0 either.


Virtually all truly diffuse materials exhibit some level of subsurface
light transport. Do make use of the corresponding feature. Since this
automatically applies a fresnelian effect to the diffuse component, you
should use `fresnel on` at the finish level to also apply a
corresponding fresnelian effect to highlights.

Virtually all dull materials still do exhibit specular highlights and
reflections, even if you don't realize it. Try to model those as such:
Use reflection and highlights (see above), and use micronormals (or
UberPOV) to achieve the diffuse-ish effect resulting from the surface
roughness.


Reflection requires something to reflect. Always make sure you have
interesting surroundings for your objects to reflect (a HDRI sky sphere
does nicely).

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