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Rune wrote:
>
> [...]
>
> I'm pretty sure there isn't. You never see highlights on materials that
> reflects mirror-like, only on materials which have "blurred reflection".
> You also don't see highlights on surfaces that don't reflect at all.
This of course depends on how you define 'highlight', but you can surely
see a bright spot on a mirror ball when illuminated by a light source like
the sun.
The reason for using specular/phong models to simulate the highlight
effect is not only to avoid calculating blurred reflection but also
because you commonly use invisible light sources.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______
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> Lately, in my modeling of textures, I have been trying to avoid using
> specular or phong highlight models (in fact, I don't know when the last
time
> I used them was) in favour of fresnel reflection, visible light sources
and
> surface 'micro-normals'
May sound attractive to use such techniques but the rendertime > down the
abyss... And doesn't look much different in the end, based on my tries...
Does fresnel make any difference unless a material has an IOR value? I
think, only transparant objects should have IOR... Tell me I'm wrong?
Regards,
Hugo
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"Hugo" <hua### [at] post3 teledk> wrote in message
news:3cdbb971@news.povray.org...
> > Lately, in my modeling of textures, I have been trying to avoid using
> > specular or phong highlight models (in fact, I don't know when the last
> time
> > I used them was) in favour of fresnel reflection, visible light sources
> and
> > surface 'micro-normals'
>
> May sound attractive to use such techniques but the rendertime > down the
> abyss... And doesn't look much different in the end, based on my tries...
> Does fresnel make any difference unless a material has an IOR value? I
> think, only transparant objects should have IOR... Tell me I'm wrong?
>
In order for fresnel to work (in 3.5) you need an ior. Read the 3.5 docs on
fresnel for a better understanding and explanation of how it works. giving
an opaque object an ior value will only affect fresnel reflections since you
can't see through the object anyways.
As for the results looking the same, this is somewhat true for circular
light sources, but not for light sources with other shapes. i.e., ambient
light coming from a square window.
I guess when it comes down to it, I'm a bit of a perfectionist and would
rather try to produce highlights in a more realistic fashion than using
highlight simulation models.
-tgq
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Christoph Hormann wrote:
> In real life there are neither highlights nor blurred reflections, only
> waves, photons, atoms and a lot of interferences and even those are only
> fairly accurate models.
Not quite true. The "Real World," what physicists refer to as "local
non-contextual reality," is composed of cars, trees, planets, apples, people
and computers. In this reality, specular highlights are indeed blurred
reflections.Wwaves, photons, atoms and quantum entanglements (interferences)
can only be measured indirectly and are not what most people consider part of
the the real world. A good joke, but a straight answer might have sufficed
here.
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Christoph Hormann <chr### [at] gmxde> wrote:
> This of course depends on how you define 'highlight', but you can surely
> see a bright spot on a mirror ball when illuminated by a light source like
> the sun.
You are just seeing the Sun reflected on the ball. :)
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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Warp wrote:
>
> [...]
>
> You are just seeing the Sun reflected on the ball. :)
>
Of course, but you don't get it in a raytracer if you just use a point
light and no specular finish.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______
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Christoph Hormann wrote:
> Warp wrote:
>> You are just seeing the Sun reflected on the ball. :)
>
> Of course, but you don't get it in a raytracer if you
> just use a point light and no specular finish.
I'm sure no one doubt that, but we were talking about real life here...
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Apr 14)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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Rune wrote:
>
> > Of course, but you don't get it in a raytracer if you
> > just use a point light and no specular finish.
>
> I'm sure no one doubt that, but we were talking about real life here...
>
This is exactly what i was talking about, in real life highlights (which i
would define as the bright spot appearing on on illuminated shiny
surfaces) are caused by reflection on the surface. Whether the reflection
is blurred or not (in other words how rough the surface is) only
influences the characteristics of the highlight.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______
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Christoph Hormann wrote:
> This is exactly what i was talking about, in real
> life highlights (which i would define as the bright
> spot appearing on on illuminated shiny surfaces) are
> caused by reflection on the surface. Whether the
> reflection is blurred or not (in other words how
> rough the surface is) only influences the
> characteristics of the highlight.
With your definition of a highlight, that is correct. I don't know what
the actual definition of a highlight is, but when I see a light bulb in
a mirror I usually don't think of it as a highlight.
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Apr 14)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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Dave Dunn wrote:
>
> [...] Wwaves, photons, atoms and quantum entanglements (interferences)
> can only be measured indirectly and are not what most people consider part of
> the the real world.
Huh? I don't see why interferences are only detectable less diretly than
cars, trees and planets, but that's merely a philosophical question of
course.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______
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