William Tracy nous apporta ses lumieres en ce 12 / 05 / 2007 08:59:
> Ansgar wrote:
>> Hello there.
>>
>> My metal textures are always a little dull and boring and I wanted to 
>> ask if
>> there are any tips you could give me to spice them up a bit. For 
>> example, is
>> it possible to define a kind of reflection map? They used to help me a 
>> lot
>> to make realistic metals in MAX but I don't know if and how I can create
>> similar effects with POV. Thanks in advance!
>>
>> Ansgar
> 
> You could take a peek at metals.inc. A lot of people don't like the 
> predefined textures that come with Pov, but I'm happy with metals.inc, 
> even if just as a starting point for my own textures. If nothing else, 
> looking at the finishes in metals.inc will give you some hints on how 
> reflections work in Pov.
> 
> You shouldn't need anything like a reflection map in Pov, since Pov is a 
> genuine, honest-to-goodness raytracer. :-)
> 
There is a problem in metals.inc: all textures have way to much ambient. I 
edited it to remove all ambient in the finish and prefer the result.
There is noting resembling a reflection map in POV-Ray, and most ray tracers as 
they don't need that artifice.
Environment and reflection maps are mostly used in raster tracers, not ray tracers.

If you need something to reflect on your metal objects, use a large sphere with 
no_image and optionaly no_shadow if your light is outside it. Set it with 
finish{ambient 1 diffuse 0} and use some of the included sky pigment on it, or 
make your own texture.
Other things you can try:
Experiment with brilliance.
Experiment with variable reflection.
Experiment with the reflection exponent.
Experiment with falloff.
Give your object an interior with an ior in the 4 to 6 range (normal for metals) 
and use fresnel in the reflection{...} block. Works best when also using 
variable reflection.
Work with the specular/roughness and/or phong/phong_size highlight.

To make things interesting and simulate a very thin varnish coat or oily film, 
you can add iridescence by adding an irid{...} block in the finish.

-- 
Alain
-------------------------------------------------
REMEMBER: WHATEVER HAPPENS, HAPPENS FOR A REASON.

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