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I'm trying to match as closely as possible the shading models available in
blender to the povray exporter.
___________________________________________________________
Blender Specular: | Povray keywords
___________________________|_______________________________
Phong |Phong (?)
Blinn |Specular (?)
Toon |
WardIso |Specular (?)
CookTorrence (default) |Specular or Phong ?
___________________________________________________________
Blender Diffuse: |
___________________________________________________________
Lambert (default) |Specular or Phong ?
Oren Nayar |Brilliance (=Oren Nayar sigma)
Toon |
Minnaert |slope map(?)
Fresnel |Specular ?
Any suggestion to modify/improve/complete this list?
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> I'm trying to match as closely as possible the shading models available in
> blender to the povray exporter.
> ___________________________________________________________
> Blender Specular: | Povray keywords
> ___________________________|_______________________________
> Phong |Phong (?)
> Blinn |Specular (?)
> Toon |
> WardIso |Specular (?)
> CookTorrence (default) |Specular or Phong ?
> ___________________________________________________________
> Blender Diffuse: |
> ___________________________________________________________
> Lambert (default) |Specular or Phong ?
> Oren Nayar |Brilliance (=Oren Nayar sigma)
> Toon |
> Minnaert |slope map(?)
> Fresnel |Specular ?
>
> Any suggestion to modify/improve/complete this list?
>
>
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
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Alain <aze### [at] qwerty org> 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?
2-What's the difference between aoi and slope_map?
Here is what I have so far:
_____________________________________________________________________________
> > Blender Specular: |Povray keywords:
_______________________________|_____________________________________________
> > Phong |Phong
_____________________________________________________________________________
> > Blinn |high brilliance, either specular or maybe use
> > |reflection, fresnel, very low exponent.
_____________________________________________________________________________
> > Toon |phong (extreme phong_size)
_____________________________________________________________________________
> > WardIso |Specular (and/or phong for a few values?)
|could access the widest range of roughness and
> > |brilliance
_____________________________________________________________________________
> > CookTorrence (default) |Phong
_____________________________________________________________________________
_____________________________________________________________________________
> > Blender Diffuse: |Povray keywords:
_____________________________________________________________________________
> > Lambert (default) |some chosen brilliance to match blender's
_____________________________________________________________________________
> > Oren Nayar |Brilliance (probably between 1 and 10)
_____________________________________________________________________________
> > Toon |brilliance probably below 1
_____________________________________________________________________________
> > Minnaert |slope map(/aoi)
> > Fresnel |(slope map/)aoi
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> 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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>> 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
Also, for the toon part:
You may also look for a finish with a low diffuse value and a high
ambient value.
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Alain <aze### [at] qwertyorg> wrote:
> >> 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
> Also, for the toon part:
> You may also look for a finish with a low diffuse value and a high
> ambient value.
Yes I had noticed about the low diffuse value. about the high ambient, I have
doubts since toon shaders still need to be able to get good dark shadows.
Thanks a lot for your help.
For the Blinn, after some tests I chose to use just the specular keyword, So I
had to leave the blender IOR feature out.
For phong an Cooktorrence, the same phong and phong_size.
For wardiso I used the specular keyword with an increased specularity when spec
area is set tighter.
About Oren Nayar:
The values below 1 for brilliance give terminator problems (blocky limit between
light and shadow) even if I forget about that, varying the brilliance doesn't
seem enough to look as good as the oren nayar. which seems to process by
lightening the edge when increasing its contrast sigma whereas brilliance rather
seems to darken by extending the shadows towards parts more influenced by light.
I still left things that way to be able to move on.
Other than that I Only have Fresnel and Minnaert left to do, but they're a pain
to conciliate with the texture system I had set up, which already had to make
use of the "russian mafia doll "finish map"" to map specular to a texture along
with alpha to a different texture along with diffuse image map and bump map.
I gave up all the other blender channels, to keep a little sanity, which I'm
preparing to waste in my fresnel / minnaert attempt :-)
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> Yes I had noticed about the low diffuse value. about the high ambient, I have
> doubts since toon shaders still need to be able to get good dark shadows.
And I forgot about the outlines.
Here, is another place to use an aoi pattern.
aoi{[0 Your_Color][0.48 Your_Color][0.48 rgb 0]}
And a suggested finish:
finish{ambient 0 diffuse 1 brilliance 0}
>
> Thanks a lot for your help.
>
> For the Blinn, after some tests I chose to use just the specular keyword, So I
> had to leave the blender IOR feature out.
> For phong an Cooktorrence, the same phong and phong_size.
> For wardiso I used the specular keyword with an increased specularity when spec
> area is set tighter.
>
>
>
>
> About Oren Nayar:
> The values below 1 for brilliance give terminator problems (blocky limit between
> light and shadow) even if I forget about that, varying the brilliance doesn't
> seem enough to look as good as the oren nayar. which seems to process by
> lightening the edge when increasing its contrast sigma whereas brilliance rather
> seems to darken by extending the shadows towards parts more influenced by light.
> I still left things that way to be able to move on.
The blockyness probably comes from the fact that you are using a mesh.
The normal of some triangles can point toward the light while the raw
triangle is facing away from it. The light don't bend around to reatch
that area.
>
> Other than that I Only have Fresnel and Minnaert left to do, but they're a pain
> to conciliate with the texture system I had set up, which already had to make
> use of the "russian mafia doll "finish map"" to map specular to a texture along
> with alpha to a different texture along with diffuse image map and bump map.
> I gave up all the other blender channels, to keep a little sanity, which I'm
> preparing to waste in my fresnel / minnaert attempt :-)
>
>
>
>
>
>
>
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Alain <aze### [at] qwertyorg> wrote:
>
> > Yes I had noticed about the low diffuse value. about the high ambient, I have
> > doubts since toon shaders still need to be able to get good dark shadows.
> And I forgot about the outlines.
> Here, is another place to use an aoi pattern.
> aoi{[0 Your_Color][0.48 Your_Color][0.48 rgb 0]}
> And a suggested finish:
> finish{ambient 0 diffuse 1 brilliance 0}
> >
> > Thanks a lot for your help.
> >
> > For the Blinn, after some tests I chose to use just the specular keyword, So I
> > had to leave the blender IOR feature out.
> > For phong an Cooktorrence, the same phong and phong_size.
> > For wardiso I used the specular keyword with an increased specularity when spec
> > area is set tighter.
> >
> >
> >
> >
> > About Oren Nayar:
> > The values below 1 for brilliance give terminator problems (blocky limit between
> > light and shadow) even if I forget about that, varying the brilliance doesn't
> > seem enough to look as good as the oren nayar. which seems to process by
> > lightening the edge when increasing its contrast sigma whereas brilliance rather
> > seems to darken by extending the shadows towards parts more influenced by light.
> > I still left things that way to be able to move on.
> The blockyness probably comes from the fact that you are using a mesh.
> The normal of some triangles can point toward the light while the raw
> triangle is facing away from it. The light don't bend around to reatch
> that area.
>
> >
> > Other than that I Only have Fresnel and Minnaert left to do, but they're a pain
> > to conciliate with the texture system I had set up, which already had to make
> > use of the "russian mafia doll "finish map"" to map specular to a texture along
> > with alpha to a different texture along with diffuse image map and bump map.
> > I gave up all the other blender channels, to keep a little sanity, which I'm
> > preparing to waste in my fresnel / minnaert attempt :-)
> >
> >
> >
> >
Good idea for the outline. If I had searched for a solution for it I would
probably have come to the same or used the slope too. But I'm not sure I will
have time to nest one more level into the texture system... :-/
for the fresnel I need to attribute the "look at" vector of lamps from the
export script and use it for povray slope direction, but the problem is a lamp
in blender is generally specified by position and rotation, not by "look at"
unless you assign a constraint to it.
Any idea about an alternative way to feed the slope direction from arcs of
rotation and position of the lamp?
Like, is it possible to specify a starting count vector and "rotate" it by my
angle even though the look at seems to just be a position? (I have access to
matrices too, and am willing to learn more about those if needed).
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Am 13.07.2010 00:27, schrieb Mr:
> Like, is it possible to specify a starting count vector and "rotate" it by my
> angle even though the look at seems to just be a position? (I have access to
> matrices too, and am willing to learn more about those if needed).
Check out the vrotate() function.
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clipka <ano### [at] anonymousorg> wrote:
> Am 13.07.2010 00:27, schrieb Mr:
> > Like, is it possible to specify a starting count vector and "rotate" it by my
> > angle even though the look at seems to just be a position? (I have access to
> > matrices too, and am willing to learn more about those if needed).
>
> Check out the vrotate() function.
I checked the documentation and maybe that section got me something even closer
to what I need: vaxis_rotate(A,B,F), which if I understood properly will allow
me to rotate the lamp locally around its own center rather then the origin.
Anyway between this and vrotate() I should be able to do what I want. Povray is
wonderfull. Thanks!
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