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Rene Bui wrote:
>>I thought the translucency you got there
>>was pretty amazing and beyond anything I was ever able to achieve.
>
> Thank you so much
>
>
>>Where do these test fit in with the results you got in your post of 9/19
>>titled Always my Wings model?
>
> Oh Jim.. you talk to me as if I just live in Canal street, but I'm not.
> Remember, my english is preteen level.
I apolgize.
> Do you mean these images are worse than my post of 9/19 ?
>
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 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. Forgive me, I
cannot think of simpler words to use. Sure wish I knew French :(
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I'm lost, don't know what SSS is, but I do know these images are very good.
- Grim
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GrimDude wrote:
> I'm lost, don't know what SSS is, but I do know these images are very good.
>
> - Grim
>
>
Sub-surface Scattering. The idea is that for many materials ( well all
materials really ) light penetrates the surface somewhat before being
refracted back. With some materials, like marble or human skin this
produces noticable effects. There are renderman shaders for instance
that attempt to reproduce these effects. Some time ago Mael and others
began experimenting with using dense media within objects, and leaving
the surface transparent, as a POV-Ray solution to this issue. The
results are a dramatic success when simulating homogenous materials such
as jade or wax. But as a way of treating skin, good results remain
elusive. This seems to be mostly because of the need for a
semitransparent rather than totally transparent surface plane to achieve
much of the information that skin offers the eye. Hence the subtle
milky effect of the dense media is lost. That's my take on it anyway.
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"Jim Charter" <jrc### [at] msn com> wrote in message
news:41ddf75e$1@news.povray.org...
> Sub-surface Scattering. The idea is that for many materials <snip - with
> apologies>
Understood now. I recall having tried to recreate SSS (so proud I can use
that now) with a slower computer than I have now and having given up. It's
been awhile. I can see why the frustration came about for Rene now.
I'll save this for later, thank you! :)
- Grim
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On Thu, 06 Jan 2005 03:20:54 -0500, Rene Bui wrote:
> Hi all,
> I'm working on skin+sss through pov media. Well... I would say : it's SSSo
> hard !
> As you know , too many translucent problems, a lot of time for tweaking
> and then waiting for render etc. etc.
> Now I say to myself : probably it's time to give up. :-(
>
> I'm not happy with the results but perhaps my eyes are simply tired.
> Anyway, here are some of my last tests.
>
>
> Rene
> (the old newbie)
Pretty good. The only problems I see are:
* Too uniform. Try adding random redder areas - at least my skin varies in
tone quite a lot. Also try adding other imperfections, and blood veins
(long areas of darker, bluish tone).
* No body hair. Human have a fur coat, even if it's sparse enough to not
be easily visible. It doesn't matter in the far shots, but closeups look a
bit weird without it. Maybe use sphere sweeps and near translucent, light
texture for it ?
* The bumbs in skin (especially the backs of hands) are not round, but
streched, all in the same direction. If you're using a bumb map, try
scaling it with 1.5 in one direction.
* Too much highlight - higlight makes skin look very greasy which
conflicts with the seemingly complete lack of dirt.
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...
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"JS" <no### [at] spammersallowed> wrote in message
news:pan### [at] spammersallowed...
>
> 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...
Yeah, that's right! Make it more... grim! Heh.
- Grim
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"Rene Bui" <ren### [at] freefr> wrote
> Hi all,
> I'm working on skin+sss through pov media. Well... I would say : it's SSSo
> hard !
> As you know , too many translucent problems, a lot of time for tweaking
and
> then waiting for render etc. etc.
> Now I say to myself : probably it's time to give up. :-(
>
> I'm not happy with the results but perhaps my eyes are simply tired.
> Anyway, here are some of my last tests.
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.
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>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. 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.
(*)But works very well as bump map
>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.
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.
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. 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...
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. So I 'm feel a bit alone with this subject.
>Forgive me, I cannot think of simpler words to use. Sure wish I knew
>French :(
Don't worry, I took time to look at my dictionary. ;-)
Rene
(the old newbie)
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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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>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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