Rene Bui wrote:
> 
>>I think the translucent look of the flesh was lost in the later images.
>>I value that translucent look more than some of the effects you
>>achieved in the later images.
> 
> I must notify an important point concerning the first image (9/19): there
> was a photograph uv-mapped, on the contrary the later images have not, it
> is a
> psp hand-made texture.
> Perhaps it's why unconsciously you make the difference. Obviously,
> photograph make things more real. 

Yes I am sure that had much to do with it.  The subtle indications of 
veins under the skin go a long way to create the illusion.



Besides, the more I learn cg/skin the
> more I think using photographs* as diffuse texture is a kind of heresy due
> to
> their inadequate lighting.

? you mean the lighting when the photo was taken?


> (*)But works very well as bump map
>

I really was wondering how you were getting the great bump textures.


> 
>>I think that it is this translucent look of the flesh, the effect of the
>>light showing through from behind, that is what people are trying to get
>>with SSS.  But maybe you achieved it another way?  I was never able to
>>accomplish that and would love to know how you did it.
> 
> Technically, I know nothing else that all people knows yet and even less.
> Often, I'm feel like a blind man in a dark room.. You know, I'm an artist
> (cg
> newbie) not a programmer.

Yes but these are very equal directions to approach cg from.  THough I 
admit, those with the ability to read the POV-Ray source and so 
understand its behavior in that way too may get to certain results more 
quickly than those of us who must conduct exhaustive trials and 
experiments.  On the other hand, a raytracing is simply a collection of 
effects, much as is a painting.


> This is why I can't bring up some good tricks to the community and also
> why I'm feel frustrated opening this thread.
> With SSS/media in pov, I can't do my own rules and use them from scene
> to scene. It's annoying. Every time I move a bit the camera or lights or
> objects, every time I have to waste many hours for tweaking and tuning
> once more.

There is much more art to it than science, yes.  Which I found to be 
thrilling when I first discovered it.  Computers had not yet done away 
with the art in representation!

> But there is one thing (maybe two) I know : the light is very important, I
> mean the balance you have to do between different sources. For example,
> the light from behind the head must be stronger enough but not too much to
> get the translucency (I use *n factor, fade_distance and fade_power), and I
> always balance at least with a low factor light from foreground because the
> radiosity can't do that alone.

Something I only recently came to understand when I was doing my shoe 
models.


  Another trick is about the ears : in some
> case,
> I detached them (within wings) from the head. So they have their own
> material and transparency (transmitting/filtering factor). The problem can
> be
> the visible border between ear and head, but in certain poses it can be
> hide.
> It depends on so many things and all situations are so different...

Ahhhh!  So that is how you did it.  So the strong translucency in the 
ear together with the delicate half tones on the face and the hint of 
veins, etc., are enough to create the illusion.


> 
> I would like to see more post about flesh in this newsgroup, it could be
> helpful for me or others. I went to Jaime's website, but he stop
> (temporarely) his skin experiments, I went to Oyonale but Gilles is very
> discreet these days, I saw your great chimp post of 01/2004 but I believe
> you never post the next step. 

Which I am acutely embarrassed about.  Certainly the intention was to 
continue that theme. That whole pursuit was intended to be a systematic 
technical investigation into each of these issues of modelling and 
texturing human form,... as well as a return to some of the issues of 
mind raised in Pierre Boulle's wonderful novel ;)  But I seem to be 
trapped in an infinite regression such that before I can do one thing I 
must first do something else.  Before humans, chimps, before chimps, 
masks,... Actually that project involved three main problems, modelling 
form, texturing flesh, and generating hair.  Actually I am more or less 
still on the hair phase, except that the hair morphed into feathers. 
Like I said, before one thing, another.  My interest is in the potential 
of using clipped shapes to get hair, rather than segmented tubes.  A 
brief look at how it is going is attached. It is going SLOWLY!


So I 'm feel a bit alone with this subject.

It's a lonely subject.  I tried in vain to get the effect of light 
coming through a grape, showing both the bloom on the skin and the seeds 
inside.  My failure was absolute at the time, but your ear gives me 
hope.  Also a recently acquired a computer that does not crash under the 
slightest strain.  So I am ready to attack some of these things again. 
But first, I must complete at least a respectable POVCOMP entry. 
Working at those large resolutions may be my undoing though!

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Attachments:
Download 'img.1006.bmp' (577 KB)

>Pretty good. The only problems I see are:
Thanks for the critics
>This is simply the old problem of computer models being mathematically
>perfect, and reality being anything but perfect, and this making
>computer-generated images seem unreal...
You've just spotted the reason of my computer interest.
Re-create life with cg seem often (99,99%) a pathetic quest, and
sometimes it can be a path to a real artistic emotion. It certainly happens
when computer art is conscious of itself..


Rene
(the old newbie)

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>Very impressive. Nevertheless, SSS (real or fake) doesn't work for me on
>human flesh (unless it's very very muted). It gives a waxy/varnished look.
Thanks..

Rene
(the old newbie)

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>? you mean the lighting when the photo was taken?
Yes !

>I really was wondering how you were getting the great bump textures.
a great photograph and a good graphics tablet !

>Which I am acutely embarrassed about.  Certainly the intention was to
>continue that theme. That whole pursuit was intended to be a systematic
>technical investigation into each of these issues of modelling and
>texturing human form,... as well as a return to some of the issues of
>mind raised in Pierre Boulle's wonderful novel ;)
"La Planete des Singes"

> But I seem to be
>trapped in an infinite regression such that before I can do one thing I
>must first do something else.  Before humans, chimps, before chimps,
>masks,...
I suppose you're walking through the grand Gallery of Evolution.

>Actually that project involved three main problems, modelling
>form, texturing flesh, and generating hair.  Actually I am more or less
>still on the hair phase, except that the hair morphed into feathers.
>Like I said, before one thing, another.  My interest is in the potential
>of using clipped shapes to get hair, rather than segmented tubes.  A
>brief look at how it is going is attached. It is going SLOWLY!
Damn.. I look foreward to see your next hair/feathers experiments because
it is the second step for me, down exactly (is it the word for the small
hair on skin ?). I've tried with C.Colefax's macro but I'm partially
satisfied.

>My failure was absolute at the time, but your ear gives me
>hope.
I'm glad to restore hope..

>So I am ready to attack some of these things again.
Cool !

>But first, I must complete at least a respectable POVCOMP entry.
>Working at those large resolutions may be my undoing though!
Work well Jim !
And for me, it's time to go to bed.. my eyes are on the floor.;-)

Rene
(the old newbie)

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"Rene Bui" <ren### [at] freefr> schreef in bericht
news:web.41dd778e422926ef5d5ac1850@news.povray.org...
> >Don't give up! (Kate Bush's or Pete Gabriel voice as you want)
> >I agree tweaking scattering media is not really a rest cure :/
>
> >Marc
>
> Thanks for the compassion.
> Oh, I luv Kate Bush !
>
I agree with Marc... about your work, AND about Kate Bush!!


Thomas

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Rene Bui wrote:
> I would like to see more post about flesh in this newsgroup, it could be
> helpful for me or others. I went to Jaime's website, but he stop
> (temporarely) his skin experiments...

    Well, thanks to your insistence I restarted the skin experiments
again (at the expense of my POVCOMP entry, but the experiment was 
interesting enough).

    I downloaded a skull from 3dcafe.com and imported it into Wings3D,
then merged the head and scaled and placed the skull inside. In the 
POV-Ray scene I used the same media-SSS I was using, with a plain white
pigment for the skull inside. Here is the comparison attached (first 
image with skull, the second hollow).

--
Jaime

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Attachments:
Download 'cabeza-sss-1.jpg' (24 KB) Download 'cabeza-sss-1-no-skull.jpg' (25 KB)

Preview of image 'cabeza-sss-1.jpg'

Preview of image 'cabeza-sss-1-no-skull.jpg'

>I agree with Marc... about your work, AND about Kate Bush!!


>Thomas

Thanks Thomas !


Rene
(the old newbie)

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>    Well, thanks to your insistence I restarted the skin experiments
>again (at the expense of my POVCOMP entry, but the experiment was
>interesting enough).
>
>--
>Jaime

Super Wow ! Your experiment was very conclusive !
Really, it seems it works !!
I think It's MUCH better than all your/my flesh images.
What you get here is very encouraging in my opinion.
I can't wait to try this.
If I gave hope to Jim, you give me hope too !
But Povcomp first. So sorry for your entry.
Promise, I stop the thread. We will talk about it after the Povcomp
deadline.
Again, many thanks.

Rene
(the old newbie)

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Rene:

In my (humble) opinion, these look very good, especially considering the 
rendering time.

Heck, if source were available, I'd use it!  (imitation and flattery and all 
..)

I think one reason that people say that skin is translucent, but then also 
say any SSS attempts look too 'waxy' is that there is a huge difference 
between real life and photo's, especially computer art.

In real life, I believe our eyes are something like 9kx9k resolution -so any 
translucence has a few 'pixels' to show.  It's small, but we see it, so we 
know it's there.

When we look at a person in CGI, there aren't nearly enough pixels to show 
this, so any SSS *visible* would look like too much.

In any event, my particular use isn't so much close ups, but I am trying to 
do a POVComp image with a couple of people on a balcony, high inside a 
'bubble city' on Mars.  I was toying with the idea of having a woman 
admiring the view, and a man next to her leaning over and 'admiring the 
view' (different view <G>).  If I do that, I would realy want a *good* 
looking skin shader, and yours comes I think pretty close.  I'm looking at 
rendering times of 1+ days at 1600x1200 alone just for my city :( so I need 
something fast, I think.

Does it look good in animations, or have you tried that yet?

        == John ==


"Rene Bui" <ren### [at] freefr> wrote in message 
news:web.41dcf90d422926ef9cc1eaf50@news.povray.org...
> #5 + ambient color
> #6 + reddish shadow_pigment to mimic translucent effect.
> #7 + light group => only skin and inner parts are concerned
> #8 + highlights
>
> Not perfect. Of course, the method could be improved.
> But very FAST render
>
> Rene
> (the old newbie)
>

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>In my (humble) opinion, these look very good, especially considering the
>rendering time.
>
>Heck, if source were available, I'd use it!  (imitation and flattery and all
>..)
>
Thanks,
No problem, the source is in povray.text.scene-files
Adapt the color_map at your convenience.

>In any event, my particular use isn't so much close ups, but I am trying to
>do a POVComp image with a couple of people on a balcony, high inside a
>'bubble city' on Mars.  I was toying with the idea of having a woman
>admiring the view, and a man next to her leaning over and 'admiring the
>view' (different view <G>).  If I do that, I would realy want a *good*
>looking skin shader, and yours comes I think pretty close.  I'm looking at
>rendering times of 1+ days at 1600x1200 alone just for my city :( so I need
>something fast, I think.
>
A couple of weeks before deadline ! Wooo , hurry up  John ! ;-)

>Does it look good in animations, or have you tried that yet?
>
>        == John ==

I don't know, never tried it yet..


Rene
(the old newbie)

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