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24 Nov 2024 15:32:37 EST (-0500)
  Torrance-Sparrow Model (Message 1 to 3 of 3)  
From: here I am
Subject: Torrance-Sparrow Model
Date: 17 Feb 2008 05:10:01
Message: <web.47b807434aeae3a4b61821680@news.povray.org>
Well this is undoubtedly true that I am not that gud in ray-tracing right now
but I am trying my best to get into this.

Basically The thing is as of now I've this scene file of a human face along u-v
coordinates and I have done texture mapping over the scene. Hence, the model is
the human face with its texture and shadow map but that doesn't look any way
close to the real face.What I mean is that it has plasticity kinda look.
And my sole purpose to use Torrance-Sparrow BRDF model is to make this face
model somewhat more realistic.But I am not sure how implement that.

I believe now you've pretty much idea about my situation.So, please give me some
suggestion over it.

Regards

Ran


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From: nemesis
Subject: Re: Torrance-Sparrow Model
Date: 17 Feb 2008 08:00:00
Message: <web.47b82ec4ebb6e9fcf33055780@news.povray.org>
I've posted this to the other thread, but anyway:

"here_I_am" <nomail@nomail> wrote:
> human face with its texture and shadow map but that doesn't look any way close
> to real face I mean that it has plasticity kinda look.
> And my sole purpose to use Torrance-Sparrow BRDF model is to make this face
> model somewhat more realistic.But I am not sure how implement that.

you see, you don't know what you're talking about.  Why do you think the
Torrence-Sparrow BRDF model will help you getting away from the plastic look?

What you really need is a BSSRDF (subsurface scattering).  Look here for the
comparison:
http://graphics.ucsd.edu/~henrik/images/imgs/face_brdf.jpg
http://graphics.ucsd.edu/~henrik/images/imgs/face_bssrdf.jpg

from the man himself, Henrik Wann Jensen, the father of photon mapping and
subsurface scattering models...

It's worth adding though that subsurface scattering is also doable with
scattering media, and povray has support for that.  Take a look at Master
Piqueres experimentation:
http://www.ignorancia.org/en/index.php?page=Skin


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From: here I am
Subject: Re: Torrance-Sparrow Model
Date: 18 Feb 2008 05:55:01
Message: <web.47b96316ebb6e9fc17829ea60@news.povray.org>
"nemesis" <nam### [at] gmailcom> wrote:
> I've posted this to the other thread, but anyway:
>
> "here_I_am" <nomail@nomail> wrote:
> > human face with its texture and shadow map but that doesn't look any way close
> > to real face I mean that it has plasticity kinda look.
> > And my sole purpose to use Torrance-Sparrow BRDF model is to make this face
> > model somewhat more realistic.But I am not sure how implement that.
>
> you see, you don't know what you're talking about.  Why do you think the
> Torrence-Sparrow BRDF model will help you getting away from the plastic look?
>
> What you really need is a BSSRDF (subsurface scattering).  Look here for the
> comparison:
> http://graphics.ucsd.edu/~henrik/images/imgs/face_brdf.jpg
> http://graphics.ucsd.edu/~henrik/images/imgs/face_bssrdf.jpg
>
> from the man himself, Henrik Wann Jensen, the father of photon mapping and
> subsurface scattering models...
>
> It's worth adding though that subsurface scattering is also doable with
> scattering media, and povray has support for that.  Take a look at Master
> Piqueres experimentation:
> http://www.ignorancia.org/en/index.php?page=Skin

I have been through those paper..and now I understand what I actually want to
do.
Basically I have this rendered model with ray traced and shadow map.
What I want to do next is to find surface interaction with light...the surface
reflectance with Blinn-Phong BRDF model...and as far as I understand I have to
I have use Monte-Carlo integration through out the surface and I am not sure
how to implement that in pov-ray.

Could you please give me a direction??


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