> Alain<aze### [at] qwertyorg>  wrote:
>
>> phong and specular highlighting can coexist in any single finish.
>> Usefull for highlight that have a sharp, bright, center area surrounded
>> by a relatively dim broad and fuzzy area.
>>
>> The toon part should use low brilliance, possibly as low as zero. That
>> make the illumination angle independant, resulting in flat textures
>> typical to most toons.
>>
>> For most models of diffuse, you shouls take a look at the brilliance. It
>> controlls the relation between the incident light angle relative to the
>> normal of the surface.
>>
>> In POV-Ray, fresnel is a reflection component. It needs an ior to work
>> (in interior), but not any transparency. If the fresnel from blender
>> affect the coloration of the highlights or reflection, then you should
>> use the metallic keyword.
>>
>> Also, take a look at the exponent and falloff for the reflection.
>>
>> Version 3.7 beta dependent:
>> aoi pattern: depends on the direction from whitch the surface is
>> observed. Takes vewing from reflection and refraction into acount.
>>
>>
>> Alain
>
> Thanks, all this will be very helpfull.
>
> Blender diffuse fresnel shader is not the ior dependant raytraced reflections,
> those can be set up separately too. instead, it's using an indice to vary the
> diffuse shading, normal dependant with it's reference ray based on the lamp, not
> on the view. Blinn on the other side is a "non raytraced specularity that
> correctly computes its intensity and extension via Snell's Law." using user
> input ior.
>
> 1-To emulate that in Pov, would an extreme exponent with raytraced reflection
> improve rendertimes to be comparable with a non raytraced specular?
I don't think so.
Blinn seems to emulate or fake fresnel based variable reflection.
>
> 2-What's the difference between aoi and slope_map?
>

Those two are similar in implementation but differs as follow:

slope depends on the orientation of a surface relative to an arbitrary, 
user defined, direction. If you move the camera, the resulting pattern 
will never change. If you view the same object directly and it's 
reflection, there is no change to the pattern.
Typicaly, the values can range from 0 to 1. There is an optional 
altitude component that allow the texture to change acording to the 
"altitude" as well as it's local slope.
In your case, it could be the lamp-object vector.
If you need it to take more than one light_source, you'll need to layer 
several pattern using partialy transparent pigments, one per light_source.

aoi depends on the orientation of a surface relative to the direction at 
whitch it is observed. If you move the camera, the resulting pattern 
will always change acording to the new location. Typical values range 
from 0 to 0.5. The 0.5 to 1 range belong to the part that's facing away 
from the point of view and normaly not visible unless the normal gets 
disturbed.
aoi is not available in version 3.6 and earlier. There is a version of 
that pattern implemented in megapov, but it don't function the same way.
____________________________________________________________________
 >>>> Toon                       |brilliance probably below 1
Change that to: brilliance under 0.25, probably closer to 0

Make some tests using a box and a plain sphere using a bland white pigment.



Alain

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