"clipka" <nomail@nomail> wrote:
> Zeke <"zeke at no spam zeke3d.com"> wrote:
> > Suppose I should do this after months and months of admiring the amazing
> > work here.
>
> Congratulations - you obviously got further than one of our pros here, who only
> managed to come up with some WIP shots of his chrome sphere ;)

Hey, I got so many complements on that scene that I wonder if it's worth
finishing.  Besides, I spent so much time on the scaffold that I don't know
that I can part with it.  The galvanized tubing, in particular, uses a 3-stage
texture map with varying ambient levels.

> One spontaneous thought: Too much ambient on the sphere (makes it look somewhat
> "dusty"); in fact, a chrome sphere should have zero ambient.

Yes, and I agree with Alain:  the ambient values in the stock metallic textures
are nauseating.

What I do is step down the ambient in complement to the reflection value.  I
also step down the diffuse in tandem, on the theory that a material reflects
light the same way whether the light is from a point source or from the
environment.  (The diffuse should be lowered anyway, on account of the law of
conservation of energy.)  Thus, if the default finish is:

   #default { finish { ambient 0.1 diffuse 0.6 } }

then a shiny chrome sphere would have:

   finish { reflection { 0.9 metallic } ambient 0.01 diffuse 0.06 }

While there's little or no noticeable difference between 0.01 and 0.00 in a
reflection-rich environment, I typically get my metals from a macro, so it's no
extra work.  A copper pipe might have:

   finish { reflection { 0.25 metallic } ambient 0.075 diffuse 0.45 }

and a laptop panel would have something like:

   finish { reflection { 0.99 1.00 fresnel } ambient 0.001 diffuse 0.006 }

An angle-of-incident-dependent material knocks out my basic ASSumption, but
usually that's not an issue.

Even where there's no specular reflection, I preserve the relation between
ambient and diffuse.  Since a sheet of paper reflects more light than the above
diffuse value, it might have:

   pigment { rgb 1 }
   finish { ambient 0.0125 diffuse 0.075 }

Of course, when radiosity is used, the only civilized #default setting is finish
{ ambient 0.0 }.  The ad hoc finishes' values are adjusted accordingly.

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