Am 16.12.2010 10:32, schrieb FlyerX:

> Some tips that worked for me:
> -no specular for any eye part. 10% reflection on eyesurface with a nice
> room HDRI background.
> -remove specular and bump from hair for faster renders. Also no specular
> on the hair or it will look like a silk cover over the head.
> -Lip: No specular and 5% reflection. Works best with a nice specular and
> bump map.
> -Skin: specular of about 0.078 and roughness about 0.025. No phong.
> -Bilinear interpolation works best for most maps. Bicubic just does not
> work well for transparencies.
> -No ambient for the skin or eyes.

I'm using radiosity for these types of scenes, so ambient is a no-go for 
me anyway ;-) (and is turned off automatically by POV-Ray 3.7)

As for specular, I intended to "sync" that with reflection intensity, 
because physically they're the very same phenomenon. It's not trivial 
though, as the proper relation between the "specular" parameter and the 
"reflection" intensity depends on the roughness of the material. Also, 
as I've learned recently, the specular highlights should follow the 
fresnel formula, which they don't. And light sources with a looks_like 
object are another problem, as they'd show up twice, once via the 
"specular" and once via the "reflection" mechanism. Blurred reflections 
would come in handy, too.

> I have been trying to modify PoseRay to get a more consistent result
> from Poser using the diffuse, specular and bump maps plus some some
> pigment macros. Unfortunately Poser materials using the node system are
> typically so badly implemented that many skin textures are just a mangle
> of useless nodes. Sometimes Poser nodes are used as a hack to get better
> rendering in a particular lighting making them useless for any other
> scene. To the node problem you can also add bad maps with specular,
> reflection and shadow effects baked in. I also think that lack of
> direction from Smith Micro on how to properly define a basic skin
> material using nodes is what creates this mess.

Yes, that's my experience, too. Ambient to simulate subsurface 
scattering - yuck! I don't want glow-in-the-dark people in my renders...

> This makes it very difficult to translate a Poser material to POV-Ray
> SDL. I am sure that each of the Poser nodes can be easily duplicated in
> POV-Ray but many times I find that just using the basic components
> (diffuse, specular, bump & transp) plus POV-Ray enhancements yield
> better results.

That's why I'm aiming for a macro framework to define the materials in 
POV-Ray: My hope is that I can just plug in the different 
image/bump/specular/transparency maps, tweak a few constants, and get 
better results than with the original materials in the original 
software, with consistent quality in all lighting situations.

> The image I attached is Stephanie 4 with the Natasha elite maps. POV-Ray
> 3.7 windows beta 40 which works much better than 3.6 for image map
> handling.

... and I happen to know why ;-) You might want to add an option to 
PoseRay though to automatically add "gamma 1.0" to specularity and 
transparency maps, as I guess they're typically intended to be consumed 
"raw" (wouldn't hurt for bump maps either, but isn't strictly necessary 
there).

Nice render, btw. If it wasn't for the hair (which in my experience is 
the most difficult part to get right), I'd call it convincing.

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